In this chapter, the current status of research on social communication in each group of nonhuman primates will be surveyed and some of the strengths and weaknesses of our present sample of communication behavior in this group of mammals will be indicated. No attempt will be made here to duplicate what has already been covered in several recent, substantive reviews of primate communication (cited below) in which the structures and functions of primate social signals have been discussed. The present survey is intended as a taxonomie guide to the available information on communication behavior in primates. The literature search for this survey was completed in June, 1966.
In its broadest sense, “communication” covers all of the ways in which the action of one being affects the behavior of another, and thus includes virtually all aspects of primate group life. We will restrict ourselves here to intraspecific and interindividual communication and will concentrate on the various patterns of primate signaling behavior.
The taxonomy that has been used here is primarily that of Simpson (1945). The tree “shrews” (Tupaiidae) have not been included in this review, both for taxonomie reasons given by Hill (1953) and because of growing evidence that they are not as closely related to the primates as had been thought (Campbell, 1966; McKenna, 1966; Van Valen, 1965).
Continued interest in the social behavior of nonhuman primates has led to the publication of a number of reviews from several viewpoints, many of which are of direct relevance to the topic of primate communication. Included are the reviews of Altmann (1962c, 1966), Andrew (1963a, b, c, 1964), Bernstein (1964e), Bolwig (1964), Bourlière (1961), Carpenter (1942a, 1945, 1952, 1958), Chance (1955, 1959, 1961), Chance and Meade (1953), Crook and Gartlan (1966), Darwin (1873, 1876), DeVore (1963), Garner (1892), Hall (1964, 1965a), Hediger and Zweifel (1962), Imanishi (1960), Klotz (1966), Marler (1965, 1966), Maslow (1935), Mason (1964), Nissen (1951), Washburn, Jay and Lancaster (1965), Yerkes (1933b) and Zuckerman (1929, 1932).
This last reference, although relying heavily upon Zuckermans own observations on hamadryas baboons in the London Zoological Gardens, was the first attempt at a synthesis of knowledge of social behavior in nonhuman primates. New information on this topic accumulated slowly during the period from the publication of Zuckerman s work until about 1955. The outstanding exceptions during that period were the brilliant studies by C. R. Carpenter (collected in Carpenter, 1964). Beginning about 1955 there was a marked accélération in the rate of research in this area. Over the last decade the rate of growth in research on naturalistic studies of primates represents a doubling of research effort every five years (Altmann 1966f); there has been a similar spurt in related work on primates in captivity. (The papers cited in this survey incorporate somewhat less than half of those in my file on primate communication and social behavior.) Thus, anyone seriously interested in social and communicative behavior in nonhuman primates should consult the more recent reviews of this topic (e.g., Altmann, 1966; Marier, 1965) or the original literature. The volumes edited by Schrier, Harlow, and Stollnitz (1964) and by DeVore (1965), both reviewed by Altmann (1965a), provide current surveys of many aspects of primate behavior. The former is devoted primarily to the results of research carried out in laboratories, the latter primarily to results from field studies. An international symposium (Altmann, 1965) and a resulting volume (Altmann, 1966f) were devoted specifically to the topic of primate communication. See also the volumes edited by Morris (1968) and by Southwick (1963).
In addition to the standard reference and abstract sources for the biological and medical sciences, students of primates have available several specialized bibliographic sources. These include the bibliographies by Rohles (1962, 1963), Sugiyama (1965b), Shilling (1964), Voss (1955), and Ruch (1941). The last is now kept current by means of a weekly listing of Unverified Primate References, available from the Primate Information Center, Regional Primate Research Center, University of Washington, Seattle, Washington. In addition there is a section on Current Literature published in the journal Folia Primatologica: International Journal of Primatology. This journal (published by S. Karger) is one of two regularly published journals of scientific research on the primates; the other is Primates: Journal of Primatology (published by the Japan Monkey Centre). An informative Laboratory Primate Newsletter is edited by Allan M. Schrier and published at the Psychology Department, Brown University, Providence, Rhode Island. Two attempts to compile the available information on primates, with emphasis on anatomy and morphology, are now being published. The first of these is Primatologia: Handbook of Primatology (S. Karger, publisher). The other is Primates: Comparative Anatomy and Taxonomy, by W. C. Osman Hill, published by Interscience and by Edinburgh University Press. (Whereas the Handbook of Primatology is organized primarily around organs and organ systems, Hill’s volumes are organized around the species of primates.) The Handbook of Primatology and the journal Folia Frimatologica are supplemented by a monograph series, Bibliotheca Frimatologica (S. Karger, publisher).
METHODS OF STUDY
In addition to the Methods sections that are included in the papers referred to in this survey, discussions of techniques for the study of primate social communication will be found in articles by Altmann (1962b, 1966b), Bobbitt, Gordon, and Jensen (1966), Carmichael (1965), Hall (1963), Hutchinson, Azrin, and Hake (1966), Jensen and Bobbitt (1965), Mason (1959), Plutchik (1964), and Schaller (1956b). See also Marler (1961), Ruesch (1953), and Sebeok (1965a,b) on communication in general. An essential part of any thorough study of a communication system is a description and analysis of the messages or signals that may be transmitted; that is, we need to know the repertoire of display patterns that is available to the animals under study. Several papers have discussed problems in identifying the fundamental units of communicative behavior in the repertoire of a species (Altmann, 1962b, 1965, 1966c; Hebb, 1949; Hebb and Thompson, 1954; Marler, 1965; Nissen, 1958; Rodriguez Delgado and Delgado, 1962; Struhsaker, 1966). We will return to this problem at the end of the chapter.
Several films on the naturalistic behavior of primates have been made in the last few years, and many of these include material on communication behavior, particularly visual display patterns. These include:* “Howler Monkeys of Barro Colorado Island”1,2 (C. R. Carpenter), “The Rhesus Monkeys of Santiago Island” 1,5 (C. and E. Schwartz), “Rhesus Monkeys in India”2 (C. H. Southwick), “Monkeys and Scholars”1 (Japanese macaques; Kyokai T. V.), “Baboon Ecology” 1,2, “Baboon Behavior”1,6 and “Baboon Social Organization” 2,6 (Washburn and DeVore), “Mountain Gorilla”2 (George Schaller), “Les Lemuriens de Madagascar”1 (J. J. Petter), “Dwarf Lemurs, Cheirogaleus major, Play of Young Animals”4 (A. and J. J. Petter), “Weasel Lemur, Lepilemur mustelianus, Defensive Behavior” 4 (J. J. Petter), “Mouse Lemur, Microcebus murinus, Transport of the Young by the Mother” 4 (J. J. Petter), “Long-nosed Tree Shrew, Tupaia glis, Laying of Scent Trail” 4 (H. Sprankel), “Sexual Behavior in Laboratory Monkeys”3 (H. E. Rosvold and L. Z. Freedman), “Nature and Development of Affection”2 (rhesus monkeys; H. F. Harlow and R. Zimmerman), “Mother Love”2,3 (Rhesus monkeys studied by H. F. Harlow and colleagues), and a film on chimpanzees in the Gombe Reserve7 (van Lawick and van Lawick-Goodall).
DESCRIPTIONS AND RECORDS OF PRIMATE VOCALIZATIONS
With the electronic equipment that is now available, auditory signals, perhaps more than those of any other sensory modality, can readily be recorded, analyzed, stored, altered, duplicated, and played back to animals (Busnel, 1963). Hill and Booth (1957) attempted to describe primate vocalizations by means of the standard international phonetic symbols. Several other techniques have been used in the literature for this purpose: (2) transcriptions or transliterations by means of the alphabet, or the alphabet modified by punctuation marks and diacritical markings such as are used in a dictionary (e.g., hough, !hö!); (3) common names already in the language for certain animal sounds (e.g., bark); (4) a verbal description of the acoustic properties of the call (e.g., “a high-pitched, wavering sound of very brief duration, repeated at irregular intervals”); (5) an analysis of physical properties of the signal (e.g., a sound spectrogram); (6) published or distributed recordings of vocalizations.
Transcriptions, either by means of the common alphabet (however modified by punctuation or diacritical marks) or by means of the phonetic alphabet, are unsatisfactory. Use of common alphabet has the advantage over the international phonetic alphabet in being more widely understood, but both techniques suffer from the fact that these alphabets were designed to transcribe the vocal patterns of only one species of primates, Homo sapiens. Many other species of primates produce vocalizations that the human vocal apparatus is physically incapable of duplicating. Verbal descriptions of the acoustic properties of a sound often suffice as a temporary expedient, but they are hardly a substitute for a spectrographic decomposition and statistical analysis of the physical parameters of the sound. Sound spectrograms in themselves, however, are not the sole solution to presenting information about animal vocalizations. They have disadvantages, first, of requiring expensive apparatus which, in its present state of development, is not capable of doing a complete Fourier analysis of the sound and, second, of being in a form that is relatively unfamiliar and that is difficult, without much practice, to “hear.” Beyond that, techniques for publishing sound spectrograms and for reconverting from a spectrogram to a sound pattern are crude at present and preelude any attempt to carry out playback experiments to analyze the sound in a different way, etc. For these latter purposes, as well as for presenting the vocal repertoire in a form that is most readily perceived by another human, recordings of vocalizations are essential and should be published or made available for distribution in conjunction with the written report of a study of primate social signals. The Library of Natural History Sounds, Laboratory of Ornithology, Cornell University, Ithaca, New York, acts as a central repository and distribution center for animal vocalizations, and several recordings of primate vocalizations are now available from that source (e.g., recordings of howler monkeys by Altmann, and of vervet monkeys by Struhsaker).
Spectrographic analyses of vocalizations have been carried out for several species of primates: rhesus monkeys by Rowell (1962); crabeating macaques by Goustard (1963); chimpanzees by Reynolds (in Marler 1965); gorillas by Schaller (1963); vervets by Struhsaker (1966); baboons by Altmann and Altmann (1965 and in preparation); night monkeys by Moynihan (1964) and by Walker (Walker et al., 1964); the aye-aye by Petter and Petter (1966); howlers by Altmann (1966e, e); several species of Madagascar lemurs by Petter (1962); squirrel monkeys by Ploog (1966), and numerous species of primates by Andrew (1963b).
NEUROLOGICAL CORRELATES OF PRIMATE SIGNALING
The anatomical and physiological correlates of primate signaling behavior have been the subjects of a number of investigations. Some of the earliest neurological work on this subject was a study of the grasp reflex of the rhesus monkey by Richter (1931) and Richter and Hines (1932, 1934). Other work on the neurological basis of this important primate behavior pattern includes the studies by Bieber and Fulton (1938), Dalsgaard-Nielsen (1944), Monnier (1946), and Taub, Ellman, and Berman (1966). Another line of investigation was initiated in 1937 with the publication of a farsighted theoretical paper by Papez (1937) on the limbic system and of the striking experimental results of Klüver and Bucy (1937, 1939), who reported marked changes in social behaviors following bilateral temporal lobotomy in rhesus monkeys. These early investigations have led to a series of studies on the neurological basis of primate social behavior; e.g., Brody and Rosvold (1952), Delgado (1963a, b, 1964), Fulton (1953), MacLean (1958, 1959, 1962), MacLean and Delgado (1953), MacLean, Ploog, and Robinson (1960), Mirsky (1960), Mirsky, Rosvold, and Pribram (1957), Pribram and Bagshaw (1953), Ploog (1964a, 1966), Robinson (1966), Rosvold, Mirsky, and Pribram (1954), and Walker and McQueen (1953).
HORMONAL CORRELATES OF PRIMATE SIGNALING
Much less attention has been devoted to other anatomical and physiological variables affecting social signaling behavior in primates. Most of the literature on the endocrine or presumed endocrine basis of primate social behavior is based upon correlations of phases of the female menstrual cycle with concomitant changes in social behavior; e.g., Ball (1937), Ball and Hartman (1935), Crawford (1940), Michael and Herbert (1963), Rowell (1963, 1966), Young and Orbison (1944), Zuckerman (1944). In other studies, hormonal changes accompanying changes in behavior have actually been measured or have been artificially produced; e.g., Brady (1964), Clark and Birch (1945), Goy and Dodsworth (1962), Goy and Eisele (1964), Mason and Brady (1964), Michael (1965), Mirsky et al. (1953), and Mirsky (1955).
OTHER CORRELATES OF PRIMATE SIGNALING
The only other anatomical system whose relation to primate communication has been extensively studied is the vocal apparatus; see Minnigerode (1965), Hill and Booth (1957), Kelemen (1963), Kelemen and Sade (1960), Stark and Schneider (1960) and references cited therein.
Of particular interest for an understanding of olfactory communication has been the series of recent reports on the skin of primates published by Montagna and his colleagues (e.g., Montagna and Ellis, 1959; Montagna and Yun, 1963), although to date these have not been carried out in conjunction with any studies on signaling functions of the pheromones or presumed pheromones produced by the cutaneous glands. Other anatomical correlates of primate behavior have been discussed by Bolwig (1964), Hill (1956), Huber (1931), Schultz (1961), Washburn and Hamburg (1965), and Zuckerman (1933).
Although there is now a growing literature on the genetics of primates (e.g., Chu and Bender, 1961; Chu and Swomley, 1961; Goodman et al., 1965), I have not been able to find a single reference on the genetic basis of any signaling pattern in a nonhuman primate.
The mammalian order Primates is, in Simpsons classification, divided into two suborders, Prosimii, including a variety of animals often called, collectively, “prosimians,” or “prosimian primates,” and Anthropoidea, including the New and Old World monkeys, the apes, and man.
Family Lemuridae (Lemurs, sensu stricto)
Very little work has been done on a social behavior of prosimian primates; Hill (1953, pages 97–99) summarized much of the early anecdotal literature on behavior of the members of this group, but commented that, “no scientific study by modern methods, of the mental status of any species of Strepsirhini (lemurs) appears yet to have been made. . .” The notable exceptions are the work of Jolly and of the Petters, which will be described below.
Lemur (Lemurs). Most of what we now know about social communication in the lemurs of Madagascar is due to the work of the Petters (1959, 1962a, b, 1965) and of Jolly (1966a, b, c). According to Petter, several members of the genus Lemur (including L. macaca, L. fulvus, L. mongoz, and L. rubriventer) produce a variety of calls that are clearly related in the various species. During a group progrèssion, the animals continuously emit a quiet grunt of variable rhythm. The call is often given first by an animal that is alarmed and spreads contagiously through the group. A mother makes her young come to her immediately by giving the same grunting sound. Doubtless calls of this form facilitate the socialization of group members. When a group is persistently alarmed, they begin by giving grunts that become louder and louder. Then suddenly all of the members of the group utter a loud “crou-crou-crou-crouou-crouiiiiiii,” which becomes still louder toward the end. This call is repeated, according to the degree of disturbance, every two to five seconds. Between times the animals grunt without stopping. A call that is peculiar to the black lemur (L. macaco) consists of a series of deep, loud, and prolonged grunts of variable intensity and tone. It is most commonly uttered by a lone individual, generally a male but occasionally a female. The ruffed lemur (L. variegatus) utters the loudest call of any member of this genus. These animals emit a series of intense roars which rise progressively and are emitted for several seconds. These roars may be followed by varied clucking sounds.
Lemur catta (the ring-tailed lemur) is one of the few species of prosimian primates whose signaling behavior has been well described, not only by Petter (1962, 1965), but also as a result of a recent field study by Jolly (1966a, b, c). According to Jolly (1966c, pp. 3-4), olfactory communication is highly developed in this species:
Scent marking includes a whole range of gesture and is associated with much visual display. The most dramatic confrontation between L. catta is the male “tail-waving.” A male first rubs his tail several times between his antebrachial glands—the spurs on his forearms— then stands on all fours, brings his tail forward over his head, and quivers it, pointing toward another animal, which usually spats and runs away. Occasionally during the stink fight, two males tail-wave at once or in succession, facing each other (at a safe distance) like the two halves of a heraldic design.
Other forms of social interaction in Lemur catta that have been described by Jolly include chasing, jump fights, friendly contact, grooming, and play. Scent marking in the species includes genital marking of branches, palmar marking of branches, marking the tail, and tail-waving. These have been described fully in a recent publication (Jolly, 1966c). According to Petter (1965), L. catta also rubs its forearms on branches that it wants to mark after having momentarily touched the glands of its forearm and armpit together by flexing its arm. (Similar behavior has been observed by Petter in the grey gentle lemur, Hapalemur griseus). In L. catta the female also marks objects with her clitoris. Observations on captive ring-tailed lemurs have been published by Ullrich (1964).
In the black lemur (L. macaco), Peter (1965, pp. 305-306) has described the marking of other individuals in the group by rubbing their anogenital region on the social partner:
In April and May, when more than one male approached the same female, the first male tried to mark the second male and usually a short quarrel and pursuit followed. In general the more dominant male succeeded in rubbing his genito-anal region on the less dominant (most often a young or an old individual). The female frequently marks objects with her clitoris as we noted for the Lemur catta, and at the height of excitement a male may rub the top of his head in his urine or excrement and seek to mark the animals he encounters.
The black lemur does not have the marking glands on the armpit and forearm that are found in L. catta; nevertheless, it does, according to Petter (1965), exhibit very similar behavior, occurring usually during moments of sexual excitement or anger. It often rubs its forearms and hands on branches.
The ruffed lemur (L. variegatus) apparently has no specialized olfactory glands, nor has any specific marking behavior been observed in this species (Petter, 1965).
Other Lemur id Primates. Olfactory signaling is well developed in other lemurid primates as well. Petter (1962b, 1965) has observed marking with urine during sexual excitement in the lesser mouse lemur (Microcebus murinus), and the dwarf lemur (Cheirogaleus major) smears branches with excrement. Petter (1965) comments that no marking behavior has yet been observed in the weasel lemur (Lepilemur), although the male has a glandular area on the scrotum.
Petter (1962b, 1965) has described and analyzed vocalization in several species of lemurid primates. Members of the genera Microcebus and Cheirogaleus (dwarf lemurs and mouse lemurs) emit auditory signals that are in general discrete and are composed chiefly of tones of a very high frequency, which are difficult for the human ear to perceive. The closely related fork-marked mouse lemur (Phanar furcifer) seems to be more vocal than members of the first two genera, but the calls of this species are not much varied. At regular intervals it emits a series of short signals with a frequency of about two kilohertz.
Family Indriidae (Indris, Sifakas, Avahis)
The indris (Indri) are well known for the long, modulated wailing that they emit in the forest. These calls are similar to those given by gibbons. Petter (1965) reports other clear signals given by indris, grunts and uniform calls resembling the noise of a klaxon horn. The sifakas (Propithecus) have only been heard to utter two different types of calls in their habitat. The first is a characteristic click-grunt from which these animals get their common Malagasy name, and the second is a series of barks that are emitted in unison by the group. The latter seem to be given in the presence of a predatory bird (Petter, 1962b). Specialized glands for olfactory marking are present in some members of this family. Sifaka males have a gland at the base of the neck that they frequently rub against tree trunks. Petter (1965, p. 306) writes:
Urination may also serve as a means of marking, as the following example of frequently observed behavior illustrates. The adult female in a family group that was moving through the forest was seen to stop for a moment and to grip a tree branch. After having urinated at length against the branch, she leapt to a neighboring branch. The male who followed her, having approached and sniffed the damp spot a long time, then rubbed the glandular zone of his neck back and forth repeatedly in it, urinated in his turn, and bounded off to follow the female.
A report on a field study of the great white sifaka (P. verreauxi) has recently been published (Jolly, 1966b; see also Jolly, 1966a).
In both sexes of the woolly lemur (Lichanotus [Avahi] laniger), glands, presumably of olfactory signaling function, have been described on the head at the level of the angle of the mandible (Bourlière, Petter, and Petter-Rousseaux, 1956), but their significance in social communication has not yet been described.
Two types of audible signals have been recognized in the woolly lemur, an almost inaudible whistling of very high frequency and a short, clear call (Petter, 1965). The scattered and largely anecdotal literature on other members of this family has been summarized by Hill (1953).
Family Daubentoniidae (the Aye-aye)
The one extant member of this family, the aye-aye, has been heard to give two calls (Petter and Petter-Rousseaux, 1959; Petter and Petter, 1966). The first call resembles the sound of two metal sheets being rubbed together. It is of short duration. Two animals, probablv of the same family, were observed to call back and forth with this vocalization; the call of one was always followed shortly by the call of the other. The other vocalization that has been heard in the species is a type of grunt that the animals emit when they are disturbed.
The aye-ayes apparently have no cutaneous glands that could be used for olfactory signaling, but Petter (1965) indicates that he and his wife have on several occasions seen these animals rubbing their penile regions upon the branches on which they travel. The fragmentary earlier literature on the aye-aye has been summarized by Hill (1953).
Family Lorisidae (Lorisiform Lemurs)
Galago (Bushbabies or Galagos). Lowther (1940, p. 439) writes that:
When the Galago [senegalensis] moholi [i.e., the lesser galago] is angry and prepared for defense or offense, it opens the mouth so wide that the labial area is stretched and the canines and premolars exposed. There is no ability to draw up the lip in a snarl or to make grimaces of any sort . . . The eyes are focused on the cause of irritation located just above its head.
The importance of the sense of smell in lorisiform lemurs is further attested to by Lowther:
The sense of smell of a galago as of other lorisiformes is well developed and still serves a more important function than in the higher primates . . . the presence of a relatively large olfactory lobe in the brain is additional evidence that the galago and the lemurs, in common with lower mammals, retain their dependence on the sense of smell . . . the galago is as inquisitive as a monkey. Unlike that animal, however, curiosity manifests itself by smelling instead of handling the strange object.
Lowther (1940, p. 448) has described eight calls in Galago senegalensis as follows:
The galago has several notes characteristic of different conditions, clearly differentiated but difficult to describe. 1. The alarm note; a shrill sound on a high pitch, which starts somewhat like a chipmunk’s scolding note, though shriller, but which ends in a whistle. This note quiets the group into frightened stillness. 2. An automatic cry, the cause of which is unknown, and which may continue for an hour. It is a piercing noise with two pitches, high and low. While the animal is making this noise it will continue its activity, eating and jumping. It does not affect the others. 3. The low clucking note like the brooding hen, but on a lower register; used when annoyed. 4. The sex note, used by the male when pursuing the female. This is a soft questioning sound of two notes. 5. The conversational note; when separated, both male and female call to each other. This note is softer than the sex note but has the same two pitches, high and low. 6. A chattering note used by the female as an expression of annoyance at the attention of the male. 7. The maternal note; a very gentle, soft, caressing sound, used by the mother when talking to the young in the nest. 8. The squeak of the young; suggestive of young mice. It might possibly be called a squeaky chirp.
Lowther (1940, p. 448) has summarized the sexual behavior of Galago senegalensis as follows :
The female of this form will accept the male only during periods of oestrus, which may last as long as five or six days. At this time she has a colorless discharge which perceptibly excites the male. He constantly smells her genitalia and just before the act of copulation the male is likely to lick the female with his long tongue. During the period of sex activity copulation has been observed to occur three or four times a night and it has also been seen in the morning when the animals would normally be sleeping. During the long periods between oestrus, the male continues his interest, although the female refuses to accept him. As he pursues her around the cage or enclosure, he utters a soft, plaintive call which I have described as the “questioning sex note.” At times the female merely keeps one jump ahead of the male and seems undisturbed by his attentions. If, however, they are continued for any considerable time, she finally turns upon him in annoyance with a chattering cry. This usually effectively discourages his attentions. Once, however, I saw the female become so angry, after chattering at the male without effect, that she turned upon him with such fury that he took to his heels in alarm. Generally speaking, the adult pair is a friendly and affecdonate couple. They are frequently found perching side by side, grooming each other, wrestling and at times embracing (rubbing noses). During the period of pregnancy the female’s disposition became far more truculent. The continued attentions of the male were repelled with increasing vigor and shortness of temper.
Lowther’s study of Galago senegalensis seems to be the most extensive study on behavior in a lorisid primate, and even her study can only be described as preliminary. For other animals in this family only fragmentary reports and casual observations are available. Ilse (1955) has described two types of stereotyped behavior involving micturition in a loris (Loris tardigradus). In the first form the animal moves along a horizontal surface, periodically lowering the pelvis and at the same time sprawling the hind legs so that a crouched position is assumed. The animal then proceeds, walking farther along the pole, dragging its hind part along its surface. The pelvis may be raised and lowered rhythmically in the course of the walk so that an undulating movement of the spine results. Every time the hindquarters touch the horizontal surface the loris passes a few drops of urine. The other pattern consists of expressing a few drops of urine on to the hand which is then rubbed together with the foot of the same side. Ilse speculates that both forms of micturition result in a territorial marking, the first through direct application of urine to a horizontal surface and the second through application of urine by means of the hands and feet. The second technique would be particularly suited to the marking of vertical surfaces. Similar urine washing has been described in galagos (Pocock, 1939; Boulenger, 1936) and in both lorisid primates and New World monkeys (Hill, 1938).
Other reports on behavior in lorisid primates will be found in Buettner-Janusch (1964), Cowgill (1964), Eibl-Eibesfeldt (1953), Narayan Rao (1927), Ramaswami and Kumar (1965), Sanderson (1937, 1940), and Sauer and Sauer (1963).
Family Tarsiidae (Tarsiers)
Tarsius (Tarsiers). Although virtually nothing is known of the behavior of tarsiers in the wild, there have been a few reports of their behavior in captivity (Catchpole and Fulton, 1939, 1943; Clark, 1924; Cook, 1939; Hill, Porter, and Southwick, 1952; Lewis, 1939; Ulmer, 1963; Wharton, 1950). When waking from sleep and sometimes when stretching themselves, they utter a high-pitched, reed-1ike call, according to Hill, which is distinctly audible from a considerable distance. In addition, Hill describes a bubbling, chirrup sound that was given by a sexually excited adult male when a female was in estrus. Other components of sexual activity described by Hill include quivering movements of the upright tail, smelling of the genital region, and social grooming. Olfactory communication in tarsiers is also suggested by cutaneous glandular areas in the median line of the epigastrium, the circumanal glands, and glands of the naked cutaneous areas of hand and foot (Hill, Porter, and Southwick, 1952).
These reports on the signal patterns of prosimians have stressed vocal and olfactory communication. These two modalities are most conspicuous, but undoubtedly these animals also utilize communication by means of other modalities, including tactile and visual signals. For example, grooming of the fur, both solitary and social, has been reported in most prosimians that have been moderately well studied. Procumbent low incisors, which are common to all living lemurs, are extensively used in grooming of the fur (Roberts, 1966). Beyond that, these teeth are used for scraping out the meat of fruits in some species (Buettner-Janusch and Andrew, 1962; Petter, 1965; Stein, 1936).
There are, however, some very real anatomical limitations on the ability of the prosimians to express themselves through visual signals. For example, Lowther (1940, p. 438) writes that, “the galagos, like the lemurs, are extraordinarily expressionless—‘notoriously blank’ as S. Zuckerman has expressed it. They cannot (A. Smith to the contrary) make grimaces or even wrinkle the brow. They can merely stare or droop their lids, move the ears and open the mouth wide enough to expose the teeth.” This lack of facial expression is primarily due to the immobility of the lips, which results in turn from the nature of the subcutaneous musculature. Huber (1931, p. 23) writes that, “the facial muscles of the lemur play no role as musculature of facial expression. Indeed we can hardly speak of facial expression in the lemur.”
The anthropoid primates consist of the New and Old World monkeys, the apes, and man. The New World monkeys are, in Simpson’s classification, divided into two families, Callithricidae, consisting of the marmosets and tamarins, and Cebidae, containing all of the remaining New World forms.
Family Cebidae (New World Titis, Capuchins, Howlers, Spider monkey, etc.)
Aotus (Night Monkeys). Night monkeys or douroucoulis (Aotus trivirgatus) have been studied in captivity by Moynihan (1964) and by Walker (1964). In Table 1 the social signals of night monkeys that were distinguished by Moynihan, together with their presumed function or the situation in which they were usually given, are presented. Walker gives sound spectrograms of approximately sixteen vocal patterns in night monkeys and anthropomorphic descriptions of their significance. He comments that these animals “utter perhaps as many as fifty vocal sounds.” I found it impossible to match the vocal patterns in these two studies. Moynihan reviews the earlier literature on the behavior of night monkeys, particularly the observations of Hill (1956), Sanderson (1961), and Andrew (1963).
Callicebus (Titi Monkeys). Titi monkeys have recently been studied by Moynihan (1966) and by Mason (1965b, 1966). These small monkeys of the neotropical forests are particularly remarkable for their elaborate vocal displays. Since most of the data from these two recent studies have not yet been published, no attempt will be made here to summarize the few data that are now available.
Alouatta (Howling Monkeys). The Panamanian howling monkeys (Alouatta palliata) are the only members of this genus for which more than anecdotal observations are available. The population of this species that inhabits the island of Barro Colorado, Panama, was the first species of nonhuman primate that was extensively studied in its natural habitat (Carpenter, 1934). The animals on the island have been studied several times since then (Collias and Southwick, 1952; Altmann, 1959, 1966e; Carpenter, 1962, Bernstein, 1964d; see also Southwick, 1962). Vocal communication in howlers has been studied much more extensively than other forms of behavior have been, partly because calls are often easier to observe in animals that live high in a dense tropical forest but also because vocal communication is particularly well developed—indeed, spectacular—in these animals. Concomitantly the howlers’ vocal apparatus and associated structures are highly specialized for the production of these calls (Kelemen and Sade, 1960; Starck and Schneider, 1960).
Approximately twenty vocalizations are now known in this species (Table 2) based upon the observations of Altmann (1959, 1966e), Carpenter (1934), and Collias and Southwick (1952). These results have been confirmed by Bernstein (1964d), who writes that, “all vocalizations described by Altmann (1959) were heard on multiple occasions” (p.95).
A variety of nonvocal social signals have been described in the Panamanian howler. These include rubbing the perineum on a tree branch (smearing an olfactant?), presenting the perineum to the social partner, smelling the branch or perineum, muzzling of infants, clinging to the mother’s belly (a pattern found in almost all species of primates), tail contact by the infant with the mother, suckling, a labio-1ingual gesture that seems to be a mating signal, social play, baring of the teeth, and several others (see references above).
Saimiri (Squirrel Monkeys). There have been several brief studies of social behavior of captive squirrel monkeys (e.g., Azrin, Hutchinson and Hake, 1963; Kirschshofer, 1963; Takashita, 1961, 1962; Rumbaugh, 1965; Vandenbergh, 1966), but by far the most extensive and intensive studies of communicative behavior in these animals are those that are being carried out by Detlev Ploog and his colleagues at the Max Planck Institute of Psychiatry (Ploog, 1963a; Ploog, Blitz, and Ploog, 1963; Ploog and MacLean, 1963; Ploog, 1966). Ploog (1966) listed thirty-seven patterns of motor behavior in squirrel monkeys; many of these patterns are of communication significance. But he commented that, “the behavior repertoire of squirrel monkeys is by no means exhausted with this list” (p. 151). In addition, twentysix sounds could be clearly distinguished by spectrographic means.
Descriptions of many of these behaviors and of their social functions will be found in the papers cited above and in several others now in preparation by members of this group. We will single out here just one of these patterns, the remarkable genital display of Saimiri sciureus. These squirrel monkeys direct an erected penis toward their social partners as a form of threat. The display is frequently accompanied by vocalizations and occasionally by a few spurts of urine. The display usually lasts from three to ten seconds, but sometimes for as long as several minutes.
The communicative significance of this display depends in part upon the participants involved in the interaction. Among adults it is often a threat behavior involved in agonistic interactions, but it is also a part of courtship. Beyond that, adult monkeys react differently to the display of an infant and of an adult. Genital displays were observed as early as the day after birth. During the period when infants spend much of their time at play, they display toward their mothers when they are not permitted to nurse immediately, toward the dominant male and other grown animals when they are threatened after having made an attempt to contact or to play with them, toward their playmate while playing, and toward the dominant male when the playmate has been playing too roughly—almost as if they were “letting off steam” to the dominant male about the playmate (in these instances the infant flees onto the back of its mother). A playmate may display in similar fashion toward the mother of another playmate if the latter “spoils the game.”
Other Cebid Monkeys. Although cebus monkeys (Cebus) have often been used in psychological studies, there is still a paucity of information about their communication behavior. The brown capuchin (Cebus apella) has been studied in captivity by Nolte (1958) and by Nolte and Dücker (1959); the white-fronted capuchin (Cebus albifrons) has been studied in captivity by Bernstein (1965). Carpenter (1935) carried out a brief study on the red spider monkey (Ateles g eoffroyi). For the other species of New World monkeys there is an embarrassing dirth of systematic research on communication behavior. The scattered and largely anecdotal reports, together with a number of original observations, have been summarized by Hill (1960, 1963).
Family Callithricidae or Hapalidae (Tamarins, Marmosets)
Social and communication behavior in marmosets and tamarins, as with most of the other species of New World monkeys, has not yet been systematically studied. We must again refer the interested reader to the compilation of Hill (1960, under Hapalidae) for a résumé of the scattered and largely anecdotal literature. See also Gruner and Krause (1963) and Lucas, Hume, and Smith (1937) on the common marmoset (Hapale jacchus) and Hampton, Hampton, and Landwehr (1966) on the cottonheaded tamarin (Oedipomidas oedipus).
Family Cercopithecidae (Old World Monkeys)
The literature on the prosimian primates and the New World monkeys, discussed above, consists for the most part of anecdotal reports and casual observations on captive animals. The literature for a few species was exceptional, but for none of the prosimians or New World monkeys is there anything like the vast and rich array of information that is available for some species of Old World monkeys. For one species of Old World monkey, the rhesus macaque, there are over one hundred publications that deal directly with communication behavior. While there is no other species of nonhuman primate for which the available information closely approaches that of the rhesus, there are several other species of Old World monkeys for which we now have a considerable body of information on communication processes.
From the standpoint of animal communication, much of the research that has been carried out on species of Old World monkeys clusters around several major aspects of the communication process. We will discuss these in rhesus monkeys, without in any way implying that the aspects that are not here discussed are either unstudied or unimportant. Following this we will survey some of the research on these same problems in other, closely related primates such as the other macaques, the baboons, hamadryas baboons, and vervets. These are all members of the subfamily Cercopithecinae, the best studied group of primates. Our survey of the literature on communication behavior in Old World monkeys will then conclude with a review of the literature on communication in monkeys of the one other subfamily, the Colobinae.
Macaca mulatta (Rhesus): Signal Repertoire. Rhesus monkeys and other, closely related Old World monkeys share a considerable repertoire of behavior patterns, doubtless indicative of their common ancestry. A detailed analysis of these behavioral homologues is now in preparation. Preliminary results have led to the suggestion (Altmann, 1966) that social organization in Old World monkeys is more divergent than would be expected from the differences in their repertoires of social signals, and thus that social evolution—at least in this group of primates—has been not so much an evolution of behavior patterns as an evolution of the uses to which the patterns were put.
In Table 3 are compiled the results of three studies of the repertoire of social signals in rhesus monkeys by Altmann (1962b, 1965d), Rowell and Hinde (1962; also Hinde and Rowell 1962) and Reynolds (1966). These reports, in turn, give references to and comparisons with briefer reports by other authors on the signal repertoire of this species.
Macaca mulatta (Rhesus): Signal Components (“Fission”). Once the repertoire of social signals for a species is reasonably well catalogued, research may follow one of two major strategies, which we will call “fission” and “fusion.” In linguistics, the counterparts are phonemic analysis, in which morphemes (words, essentially) are decomposed (“fission”) into the meaningless but differentiating phonemes, and the study of grammar, which deals with the rules for combining morphemes (“fusion”) into sentences or statements. The process of fission, or taking signals apart, involves, ultimately, physical analysis of signal parameters (e.g., spectrographic analysis of vocal displays), determination of the signal components that are attended to by the recipient individuals, and study of the effects of this signal reception on the recipient’s behavior. The paradigm in ethological research is the use of physical models, in which it is shown, for example, that the territorial aggression of a nesting male robin can be elicited by nothing more than a wad of cotton that has been dyed red to simulate the color of a rival male’s breast.
The counterpart to such studies in primate research includes the well-known studies by H. F. Harlow and his colleagues at the University of Wisconsin, which utilize an artificial, surrogate mother to which components may be added or removed (see Alexander and Harlow, 1965; Cross and Harlow, 1963; Hansen, 1966; Harlow, 1962; Seay, Alexander, and Harlow, 1964; Seay, Hansen, and Harlow, 1962, 1965; Harlow and Harlow, 1965, and citations therein). This research has led to the suggestion (Harlow and Harlow, 1965, p. 299) that:
Clinging is the primary variable underlying infant-mother affection, but . . . many other variables operate as well. These include nursing, warmth and proprioceptive stimulation. Without doubt, there are also visual and auditory variables, both unlearned and learned, but we have not yet subjected these to detailed analysis.
Components of facial expressions, not only in rhesus, but in numerous other primates as well, are being studied by Hooff (1962). The relative efficacy of various facial expressions in eliciting affective responses in rhesus is being studied by Miller (1966; see also Miller, Banks, and Kuwahara, 1966; Miller, Murphy, and Mirsky, 1959a, b; Mirsky, Miller, and Murphy, 1958), using television cameras and cinematography to pick up, record, and transmit the displays of one monkey to another. Similar analysis can be carried out with apparatus used by Mason and Hollis (1962), or by means of a “Butler box,” combined with projected slides, motion pictures, or sound recordings (Butler, 1965, and references therein; Sackett, 1965).
Vocal communication has certain inherent advantages over visual signals for such research, in that the physical parameters of an auditory signal can readily be manipulated (by means of filters, changes in time or frequency parameters, etc.), so that one can, for example, eliminate harmonic overtones from a vocalization and leave only the fundamental sounds. With visual signals, however, alterations in many signal components would be very difficult. Beyond that, a visual display invariably includes much extraneous background “noise.” (So far, it is only in Wonderland that one can have a grin without a cat.) To date, virtually no research on primate communication has capitalized on these advantages of auditory signals.
Macaca mulatta (Rhesus): Signal “Fusion.” The study of signal “fusion,” a complementary form of research on communication, deals with the incorporation of elemental patterns of social behavior into more inclusive systems. Theoretical aspects of “fusion analysis” of primate social signals have been discussed by Altmann (1965d) and Zhinkin (1963). Three systems or modes of rhesian behavior have been the primary subjects of such studies: sexual behavior, motherinfant relations, and agonistic interactions. The work on sexual behavior in rhesus goes back at least to the work by Hamilton (1914). Except for brief studies during the interim period, the subject of sexual behavior in rhesus lay fallow until the study by Carpenter (1942b) on sexual behavior in free-ranging rhesus monkeys on the island of Cayo Santiago. The studies on sexual behavior in the Cayo Santiago population have been continued by Altmann (1962b), Conaway and Koford (1965), and Kaufmann (1965). There have, in addition, been several studies on the sexual behavior of rhesus monkeys in cages or large enclosures (Bernstein, 1963; Freedman and Rosvold, 1962; Kuehn and Young, 1965).
Most of the work on mother-infant relations and on the ontogeny of social behavior in rhesus monkeys has been carried out, as indicated above, by observing the effects of deprivation of certain basic social signals upon the later behavior of the infant. In addition to the work cited above from the Wisconsin group, this powerful technique has also been used in studies of social behavior of rhesus monkeys by Mason (1960, 1961a, b, 1963), Mason and Sponholz (1963), Hinde, Spencer-Booth, and Bruce (1966), Foley (1934, 1935), and Green (1965). Certain other studies on the development of social behavior in rhesus may be regarded as normative studies in the sense that they are an attempt to see how the infant develops when exposed to social stimuli of the sort that the infants presumably are exposed to in the native habitat of the animals. Such work began with the pioneering observations by Lashley and Watson (1913) and Tinklepaugh and Hartman (1932). More recent studies along these lines have included work by Bernstein and Mason (1962), Hansen (1966), Hinde, Rowell, and Spencer-Booth (1964), Hinde (1965), Hines (1942), Mowbray and Cadell (1962), Rowell (1964), Rowell, Hinde, and Spencer-Booth (1964), Seay (1966), and Spencer-Booth, Hinde, and Bruce (1965).
A third major category of social interactions that have been studied in rhesus monkeys is agonistic behavior, including dominance, aggression, submissive behavior, and social hierarchies. Work on this topic in rhesus goes back at least to work by Maslow (e.g., Maslow 1936a, b, 1940; Maslow and Franzbaum, 1936). More recent studies have been carried out by Bernstein (1964a, b, c), Bernstein and Mason (1963a, b), Biernoff, Leary, and Littman (1964), Chance (1955a, 1956), Horel, Treichler, and Meyer (1963), Leary and Maroney (1962), Maroney, Warren, and Sinha (1959), Mason, Green, and Posepanko (1960), Miller and Banks (1962), Mirsky (1960), Murphy and Miller (1956), and Warren and Maroney (1958).
Unfortunately, much of the literature on “dominance” in primates has relied upon a competitive food-getting situation. That is, a piece of choice food, such as a peanut or grape, is placed in such a position that the various animals being tested have access to it. An animal’s “dominance score” is then based on the total number of pieces of food that he obtains. This technique, though expedient, has a number of disadvantages in studying social relations. For one thing it is not, in fact, a study of social behavior per se, since the interactions between the individuals are not included in the dominance score. There is nothing more ludicrous than to watch a juvenile monkey grab a peanut from the vicinity of an adult male, be threatened by the male, run away from the male, screaming and defecating, but with the peanut in his cheek pouch, and then to have this event scored as a point for the juvenile. It cannot even be maintained that the food competition situation, though not based directly on observations of social relations, is a good indirect indication of these relations: correlations are generally weak between “dominance status,” as determined by competition for food, and agonistic social interactions between the monkeys (Warren and Maroney, 1958).
Macaca fuscata (Japanese Macaque). Of the remaining species of monkeys of the genus Macaca, only a few have had more than cursory studies. Particularly noteworthy have been the extensive studies of Macaca fuscata, the macaque monkey that is indigenous to the islands of Japan. The scientific study of Macaca fuscata began in 1948 with the field work of J. Itani under the direction of K. Imanishi. Since that time a number of other workers have joined the group, and in 1956 they formed the Japan Monkey Centre. While the Japanese macaque is still the basic research animal for members of the Centre, these workers are now carrying out a varied program of research on several other species of primates as well. A collection of translations into English of several important early works by members of the Centre, together with a bibliography of primate behavioral research in Japan, mostly on Macaca fuscata, is available (Altmann, 1965b). Of particular import for the present review is a paper by Itani (1963) on vocal communication of Japanese macaques (see also Itani, 1951). Itani describes some thirty-eight vocal patterns in M. fuscata, which he groups as follows: (1) sounds generally emitted in peaceful states of emotion (i.e., nonagonistic sounds), (2) defensive sounds, (3) progressive sounds, (4) warning sounds, (5) sounds peculiar to the females in estrus, (6) sounds peculiar to babies and infants.
In reading the reports of research on Macaca fuscata by members of the Japan Monkey Centre it is quite apparent that most, if not all, of the behavior patterns that they see in the species are highly similar in structure and function to those that have been described for the rhesus macaque (see, for example, Itani, 1954). However, with few exceptions (e.g., Itani, 1963; Tokuda, 1961; 1962), there have been no reports specifically identifying the basic units of communication behavior in this species. For reviews in English of the work on the Japanese macaque, see Frisch (1959, 1963), Itani (1961), Imanishi (1960, 1964), and Miyadi (1965).
Macaca nemestrina (Pig-tailed Macaques). Social interactions in the pig-tailed macaque (M. nemestrina) are now being intensively studied in at least two laboratories (Jensen, 1965; Jensen and Tolman, 1962; Bobbitt, Jensen, and Gordon, 1964; Jensen, Bobbitt, and Gordon, 1966; Rosenblum, Kaufman, and Stynes, 1966; Rosenblum and Kaufman, 1966; and references cited therein). To date little has been published about the behavior of these animals in their natural habitat. A field study by I. Bernstein has recently been completed.
Macaca radiata (Bonnet Macaques); Other Macaques. The bonnet macaque (M. radiata) has also been used more frequently in recent years as a subject for laboratory research on social behavior (e.g., Rosenblum and Kaufman, 1966; Rosenblum, Kaufman, and Stynes, 1966), and has been studied in its natural habitat by Simonds (1965) and Nolte (1955a, b).
For other macaques the literature is at present much more limited, but there is a welcome recent trend to broaden the number of species that are being studied [see, for example, Akitsu (1959) on the Formosan rock macaque (M. cyclopis); Lahiri and Southwick (1966) on the Barbary ape (M. sylvana), and Goustard (1961, 1963) and Thompson (1965) on crab-eating macaques (M. irus)].
Papio (Baboons). The baboons and related animals have been referred to in the literature under a great variety of scientific names, but it seems clear from the data that are now available for these animals that the older literature is indicative of a far more extensive taxonomie splitting than can now be substantiated. Without implying any évaluation of the taxonomie data, we will here adopt the terminology of Buettner-Janusch (1966) and include within the genus Papio four species: P. sphinx (mandrill, drill), P. cynocephalus (common baboon), P. gelada (gelada baboon), and P. hamadnjas (sacred or hamadryas baboon). The close affinities of baboons and macaques is clearly indicated by the large number of shared behavior patterns in their repertoires of social behavior.
Papio sphinx, P. gelada. Virtually no information beyond anecdotal reports is now available on patterns of social communication in drills, mandrills, or gelada baboons (see Ruch, 1941, for references). It is hoped that this situation will soon be rectified by reports on recent and ongoing studies, e.g., on geladas by J. H. Crook and by H. Kummer.
Papio hamadryas. The early studies by Zuckerman (1932) were among the first modern studies of social interactions in primates. Fortunately, we now have the benefit of further studies on this fascinating species both in captivity (Kummer, 1956, 1957; Heinroth- Berger, 1959) and in their native habitat (Kummer, 1967, 1968; Kummer and Kurt, 1963,1965).
Papio cynocephalus. The remaining, subsaharan baboons, here referred to collectively as Papio cynocephalus, have been the subjects of several recent behavioral and ecological studies in the natural habitats of these animals. These studies have been carried out by Altmann and Altmann (1965 and publications in preparation), Bolwig (1959), Devore (1962, 1963b, 1965), Devore and Washburn (1963), Hall (1960, 1962, 1965c), Hall and Devore (1965), Maxim and Buettner-Janusch (1963), Rowell (1966a, b), and Washburn and Devore (1961). Despite this growing background of information on these animals in their natural habitat, there have been only a few studies of their social behavior in captivity (e.g., Bolwig, 1963; Bopp, 1953, 1954, 1962; Gillman, 1939; and Rowell, 1965). For references to other reports on baboon behavior see Shilling (1965). Bowden (1966) describes and quotes results of recent studies on baboon behavior at Russia’s Sukhumi Station, on the Black Sea. See also Zhinkin (1963).
Cercocebus (Mangabeys). Very little is known about communication behavior in mangabeys; the scattered early literature will be summarized by Hill (in preparation). A field study on sooty mangabeys (Cercocebus albigena) is now underway (by N. Chalmers).
Cercopithecus, Miopithecus, Allenopithecus, Erythrocebus. The remaining Old World monkeys other than the colobines belong to several closely related species whose demarcations and relations are particularly difficult (vide Hill, 1966). For most species in this group
Communication behavior in three species of monkeys from this group has been studied in recent years, in each case in their natural habitat. The African redtail monkey (Cercopithecus ascanius) has been studied by Buxton (1952) and Haddow (1951). The patas monkey (Erythrocebus patas) has recently been studied both in the laboratory and in the field by Hall and his colleagues (Hall 1965a, b, 1966; Hall, Boelkins, and Goswell, 1965; Goswell and Gartlan, 1965); see also Bolwig (1963). Vervet monkeys (Cercopithecus aethiops) have been studied by Booth (1962), Hall and Gartlan (1965), and Struhsaker (1965, 1966). Struhsaker’s study is an outstanding example of what can be accomplished in the field, even starting with a relatively unstudied species, when close, persistent, and careful observations are combined with a population of animals living in a superb study area. Struhsaker has described thirty-six distinct vocalizations and other sounds, as well as sixty physically distinct inaudible behavior patterns; many of these auditory and nonauditory patterns are of communication significance within and between social groups of vervets. Table 4 (from Struhsaker, 1966) summarizes the signaling function of vocalizations in vervets. Other observations on communication behavior in monkeys of the Cercopithecus group include those of Booth (1962), Hill (1966a), Krumbiegel (1962), Pournelle (1962), and Takeshita (1961, 1962).
The remaining Old World monkeys (subfamily Colobinae) differ from the others (subfamily Cercopithecinae) in not having cheek pouches, but having sacculated stomachs. They are primarily leafeaters, and the sacculated stomach is apparently an adaptation to the habit of feeding upon large quantities of material with a relatively low nutritional concentration. Vocalizations in a large number of African and Asiatic monkeys of this group, as well as the underlying laryngeal structures, have been briefly described by Hill and Booth (1957).
Colobus (Guerezas, Colobs). Very little is known about social communication in most of the African colobine primates. Exceptions are the olive colobus monkey (Procolobus [=Colobus] verus), which has been studied by Booth (1957), and the black-and-white colobus (Colobus “guereza”), which has been studied by Ullrich (1961); see also Kirchshof er (1960).
Presbytis (Langurs). The langur monkeys have been more extensively studied than any of the other colobines, thanks to a series of recent field studies by Jay (1962, 1963a, b, 1965), Ripley (1965, 1966), and Sugiyama and colleagues (Sugiyama, 1964, 1965a, 1966; Sugiyama, Yoshiba, and Pathasarathy, 1965), all of whom have studied Presbytis entellus, the so-called common langur, and by Tanaka (1965), who has studied the Nilgiri langur, Presbytis johni.
Other Colobine Primates. There are few reports on social communication in other species of colobine primates; see Kern (1964, 1965) on the proboscis monkey (Nasalis larvatus), Furuya (1961) on the silvered leaf monkey (Trachypithecus cristatus), and Stott and Selsor (1961) on the maroon leaf monkey (Presbytis rubicunda).
Symphalangus (Siamang). Virtually nothing is known about the communication behavior of the siamang either in captivity or in its natural habitat. Scattered observations have been published by Gray (1861) and Moszkowski (1908).
Hylobates (Gibbons). The first intensive study of social communication in gibbons was Carpenters field study on the common whitehanded gibbon (Hylobates lar) (Carpenter, 1940). A more recent field study of this species has been completed (Ellefson, 1965, in preparation). Social activities in gibbons have also been studied by Bernstein and Schusterman (1964), Candler (1903), Meyer-Holzapfel (1950), Moszkowski (1908), Robinson (1925), and Boutan (1913).
Gorilla (Gorillas). The extensive study by Schaller and Emlen on the mountain gorilla completely supplants all of the previous reports on these animals (Schaller, 1963, 1965a; Emlen, 1962; Schaller and Emlen, 1963). The early literature on the mountain gorilla has been summarized by Schaller (1963). See also Schenkel (1964).
Pongo (Orangutan). There have been several attempts to study orangutans in their natural habitat or in seminatural conditions, but none of these have provided much information on communication behavior in these animals (Carpenter, 1938; Davenport, 1966; Okano, 1965; Harrisson, 1962, 1963; Schaller, 1961). Casual observations have been made by a number of people, generally on captive animals (e.g., Wallace, 1856a, b; Schmidt, 1878; Hornaday, 1879).
Pan (Chimpanzees). There have been several studies of chimpanzees in their natural habitat. The early study by Nissen (1931) was, by contemporary standards, relatively unproductive. More recent observations on these animals in their natural habitat include the studies by Reynolds (1963, 1965a, b, c) and Goodall (1963, 1964, 1965). This last study—one of the most prolonged studies ever undertaken on a primate in its natural habitat—has been described in several popular articles, but scientific reports on the results of this study (except as cited above) are still in preparation.
Several studies on communication and social behavior in chimpan zees have been undertaken in laboratories and zoos. The considerable interest in the great apes stems, of course, from their taxonomie proximity to humans. Chimpanzees have the additional advantages of being relatively more interactive than the other great apes and of being more readily available. Consequently, there is now a considerable fund of information on the social interactions of these animals. Among the most relevant for our present topic are the reports by Bingham (1927), Crawford (1942), Finch (1942), Foley (1935a), Hayes (1950), Hayes and Hayes (1954), Hebb (1945), Jacobsen and Yoshioka (1932), Kirchofer (1962), Ladigina-Kohts (1921), Mason (1965a), Mason and Berkson (1962), Mason, Hollis, and Sharpe (1962), Mason, Saxon, and Sharpe (1963), McCulloch (1939), Nowlis (1941), Schenkel (1964), Steinbacher (1940), Tinklepaugh (1933), Tomilin and Yerkes (1935), Yerkes (e.g., 1933a, 1934, 1936, 1939, 1943), Yerkes and Learned (1925), Yerkes and Elder (1936), Yerkes and Tomilin (1935), and Yerkes and Yerkes (1935). Other literature on the chimpanzee has been compiled by Rohles (1962, 1963) and Allesch (1921a, 1921b).
Homo sapiens (Humans). Of course, much of the interest in social communication of nonhuman primates and of other animals lies in the fact that our own systems of social communication are so rich, complex, and informative. Several authors have discussed the social behavior of man in a biological context. These include Bolwig (1962), Count (1958), Etkin (1963), Goodhart (1964), Hallowell (1956, 1960, 1961), Herschberger (1948), Hockett and Ascher (1964), Hutchinson (1959, 1963), Imanishi (1958, 1961), Jay (1963a), Kempf (1917), Kroeber (1928), Lenneberg (1964), Maslow, Rand, and Newman (1960), Miller (1928, 1931), Montagu (1949, 1959), Piveteau (1961), Ploog (1963b, 1964b, c), Russell and Russell (1961), Sahlins (1959), Service (1963), Turner (1957), Washburn (1963a, b), Washburn and DeVore (1961), Washburn and Howell (1960), and Zuckerman (1958).
Of particular interest in the context of this survey are several recent papers that deal more specifically with human communication in a biological setting. An entire field of science, linguistics, is devoted to the study of language, the dominant form of communication in the human primate. More recently, other, nonlinguistic forms of human communication have begun to receive attention, primarily under the rubrics of paralinguistics and kinesics (Sebeok, Hayes, and Bateson, 1964). Human communication in the context of our present knowledge of communication in other animals, particularly other primates, has been presented in the reports of Altmann (1966c), Barnett (1961), Bastian (1964, 1965), Hockett (1960), and Sebeok (1962, 1965a); see also the earlier papers by Benvenieste (1952), Bierens de Haan (1929), Haidane (1953, 1954, 1955), Pumphrey (1951), and Révész (1944).
There is at present no species of primate (nor, so far as I know, of nonprimate) for which the repertoire of social signals has been catalogued according to any adequate set of explicit, operational criteria. Not surprising, then, is the remark of Sebeok (1965b) that, “of the approximately one million species that are known, give or take ten thousand, the coding behavior of not one single animal is known.”
With few exceptions, present-day students of animal communication seem unaware of the criteria that they, themselves, have used in establishing catalogues of behavior units. Each catalogue is presented as a fait accompli, with little or no justification for the particular choice of behavioral units or elements. Yet, what stage in our research could be more crucial than this initial choosing of behavioral units! Upon it rest all of our subsequent records of communication interactions and any conclusions that we may draw from them, as well as any attempt by others to replicate our results.
No set of criteria will be propounded here; rather, we will pose a series of questions that should help investigators to select criteria and to make that selection explicit. (1) Is the catalogue exhaustive, and are the elements exclusive, such that one and only one element will occur in each event in an interaction? (2) Is the classification based solely on physical characteristics of the signals, or is it based, as well, upon the responses to these signals? (3) If a motor pattern was composed of a concatenation of distinct subpatterns, how was it decided whether to split or lump the subpatterns? (4) Has the classification produced any behavior element that is physically impossible unless it is preceded by a particular other element, e.g., one that gets the animal into an appropriate position to carry out the behavior that follows? In other words, could there be any statements of the form, “B was always preceded by A,” that are statements of physical necessity, rather than behavioral regularity? Similarly, are there any physically necessary linkages of the form, “B always follows A”? If, for some pair of elements, both linkages exist, why have these elements been separated in the catalogue? (5) Are combinations of elemental acts considered as part of the repertoire? How, for example, would barking while tail-wagging have been recorded? Did the classifications of such acts depend upon whether the components ever occurred independently? On whether they then had any signaling function? Are any signal combinations physically impossible? (6) What physical characteristics of signals were used to classify them? By what criteria were these characteristics weighted? If a physical characteristic clearly demarcated two subsets of signals, but the recipients of the signal ignored this distinction and responded in essentially the same way to signals of either subset, were the two subsets lumped together as a single unit of behavior? (7) Was only the onset of signals recorded? If so, what if signal B (e.g., barking) began well after signal A (e.g., tail-wagging) had started, but before signal A terminated? (8) What did you do about contextual signals? About signals that were virtually omnipresent, such as marks used in sex recognition or species recognition, in contrast to more transient displays that may be turned on and off? How about idiosyncratic components that might be used for recognizing an individual? (9) Were variations in signal intensity recorded? (10) Was each repetition of a signal (e.g., each wag of the tail, each pelvic thrust, each bark) recorded? Were repetitions recorded only for behaviors that are not usually repetitive? (11) Do the criteria that were used result in a unique classification of the signal repertoire?
We do not pretend that these questions are easy to answer. They are offered in the hope that the attempt to answer them will help to clarify the basis of signal analysis.
* The films are available from one or the other of the sources listed below, as indicated by the superscript numbers following the titles.
1. Primate Film Library, Unit of Primatology and Human Evolution, Royal Free Hospital School of Medicine, 8 Hunter Street, London, W. C. 1, England.
2. Psychological Cinema Register, Pennsylvania State University, University Park, Pennsylvania.
3. Visual Instruction Division, Department of Extension, University of Alberta, Edmonton, Alberta, Canada.
4. Encyclopedia Cinematographica, Institut für den Wissenschaftlichen Film, Göttingen, Germany, or, in the United States, from Audio-Visual Aids Library, Pennsylvania State University, University Park, Pennsylvania.
5. Communicable Diseases Center, U.S. Public Health Service, Atlanta, Georgia.
6. Department of Visual Communication, University Extension, University of California, Berkeley, California.
7. National Geographic Society, Washington, D.C.
Akitsu, M., 1959. On the rhythmic lip-movements of the Macaca cyclopis (in Japanese). Ann. Anim. Psychol., 9:85-89.
Alexander, B. K., and Harlow, H. F., 1965. Social behavior of juvenile rhesus monkeys subjected to different rearing conditions during the first six months of life. Zool. Jb. Physiol, 71:489-508.
Allesch, G. J. N., 1921. Geburt und erste Lebensmonate eines Schimpansen. Naturwissenschaften, 39:774-776.
——, 1921. Bericht über die drei ersten Lebensmonate eines Schimpansen. Sitz. cl. Pro. Ak. d. Wiss., Berlin, 672-685.
Altmann, S. A., 1959. Field observations on a howling monkey society. J. Mammal, 40:317-330.
——, 1962a. Primate social behavior. Curr. Anthrop., 3: 100.
——, 1962b. A field study of the sociobiology of rhesus monkeys. Macaca mulatta. Ann. N. Y. Acad. Sei. 102: 338-435.
——, 1962c. Social behavior of anthropoid primates: analysis of recent concepts. In Roots of Behavior, E. L. Bliss, ed., New York, Hoeber-Harper, pp. 277-285.
——, 1965a. Primate behavior in review. Science, 150:1440-1442.
——, ed. 1965b. Japanese Monkeys: A collection of translations. Atlanta, Yerkes Regional Primate Research Center, Published by the editor. 151 pp.
——, 1965c. Primates: communication and social interaction. Science, 149:886-887.
——, 1965d. Sociobiology of rhesus monkeys. II. Stochastics of social communication. J. Theor. Biol, 8:490-522.
——, 1966a. Discussion of reproductive behavior. In Social Communication among Primates, S. A. Altmann, ed., University of Chicago Press, pp. 55-59.
——, 1966b. Editor’s Comments, ibid. pp. 371-78.
——, 1966c. The structure of primate social communication, ibid., pp. 325-362.
——, 1966d. Primate field studies: development of a research area. In preparation.
——, 1966e. Vocal communication in howling monkeys. (7.5 i.p.s. tape). Library of Natural History Sounds, Laboratory of Ornithology, Cornell University.
——, ed. 1966f. Social Communication among Primates. Chicago: University of Chicago Press. 392 pp.
——, and Altmann, J., 1965. Vocal communication in wild baboons. Amer. Zool., 5:694.
Andrew, R. J., 1963a. Trends apparent in the evolution of vocalization in the Old World monkeys and apes. Symp. Zool. Soc. Lond., No. 10, pp. 89-101.
——, 1963b. The origin and evolution of the calls and facial expressions of the primates. Behaviour, 20:1-109.
——, 1963c. Evolution of facial expression. Science, 142:1034-1041.
——, 1964. The displays of the primates. In Evolutionary and Genetic Biology of Primates. J. Buettner-Janusch, ed., 2 vols, New York: Academic Press, pp. 227-309.
Azrin, N. H., R. R. Hutchinson, and I. F. Hake, 1963. Pain-induced fighting in the squirrel monkey. J. Exp. Anal. Behav., 6:620.
Ball, J., 1937. Sexual responsiveness and temporally related physiological events during pregnancy in the rhesus monkey. Anat. Ree., 67:507-512.
——, and C. G. Hartman, 1935. Sexual excitability as related to the menstrual cycle in the monkey. Amer. J. Obstet. Gynec., 29:117-119.
Barnett, S. A., 1961. Communication in animal and human societies. In Darwinism and the Study of Society. M. Benton, ed., Chicago: Triangle Books, London: Travistock Publications. 191 pp.
Bastian, J., 1964. The biological background of man’s languages. In Monograph Series on Languages and Linguistics, No. 17, C. I. J. M. Stuart, ed., Washington, D.C.: Georgetown University, Institute of Languages, pp. 141-148.
——, 1965. Primate signaling systems and human languages. In Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, ed., New York: Holt, Rinehart and Winston, pp. 585-606.
Benveniste, E., 1952. Animal communication and human language. Diogenes, 1-7.
Bernstein, I. S., 1963. Social activities related to rhesus monkey consort behavior. Psych. Rep., 13:375-379.
——, 1964a. Role of the dominant male rhesus monkey in response to external challenges to the group. J. Comp. Physiol. Psych., 57:404-406.
——, 1964b. Group social patterns as influenced by removal and later reintroduction of the dominant male rhesus. Psych. Rep., 14:3-10.
——, 1964c. The integration of rhesus monkeys introduced to a group. Folia Primat., 2:50-63.
——, 1964d. A field study of the activities of howler monkeys. Anim. Behav., 12:92-97.
——, 1964e. A comparison of New and Old World monkey social organizations and behavior. Amer. J. Phys. Anthrop., 22:233-237.
——, 1965. Activity patterns in a cebus monkey group. Folia Primat., 3:211-224.
——, and W. A. Mason, 1962. The effects of age and stimulus conditions on the emotional responses of rhesus monkeys: responses to complex stimuli. J. Genet. Psych., 101:279-298.
——, and, 1963a. Group formation by rhesus monkeys. Anim. Behav., 11:28-31.
——, and, 1963b. Activity patterns of rhesus monkeys in a social group. Anim. Behav., 11:455-459.
——, and R. J. Schusterman, 1964. The activity of gibbons in a social group. Folia Primat., 2:161-170.
Bieber, I., and J. F. Fulton, 1938. Relation of the cerebral cortex to the grasp reflex and to postural and righting reflexes. A. M. A. Arch. Neurol. Psychiat., 39:433-453.
Bierens de Haan, J. A., 1929. Animal language in relation to that of man. Biol. Rev., 4:249-268.
Biernoff, A., R. W. Leary, and R. A. Littman, 1964. Dominance behavior of paired primates in two settings. J. Abnorm. Soc. Psychol., 68:109-113.
Bingham, H. C., 1927. Parental play of chimpanzees. J. Mammal, 8:77-89.
Bobbitt, R. A., G. D. Jensen, and B. N. Gordon, 1964. Behavioral elements (taxonomy) for observing mother-infant-peer interaction in Macaca nemestrina. Primates, 5:72-79.
——, B. N. Gordon, and G. D. Jensen, 1966. Development and application of an observational method: continuing reliability tests. J. Psychol, 63:83-88.
Bolwig, N., 1957. Some observations on the habits of the Chacma baboon, Papio ursinus. S. Afr. J. Sei., 53:255-260.
——, 1959. A study of the behavior of the Chacma baboon, Papio ursinus. Behaviour, 14:136-163.
——, 1962. Some thoughts on man, primates and their evolution. VIe Cong. Int. Sei. Anthrop. Ethnol, Paris 1960, 1:563-564.
——, 1963a. Observations on the mental and manipulation abilities of a captive baboon (Papio doguera). Behaviour, 22:24-40.
——, 1963b. Bringing up a young monkey (Erythrocebus patas). Behaviour, 21:300-330.
——, 1964. Facial expression in primates with remarks on a parallel development in certain carnivores (a preliminary report on work in progress). Behaviour, 22:167-192.
Booth, A. H., 1957. Observations on the natural history of the Olive Colobus monkey, Procolobus verus (van Beneden). Proc. Zool. Soc. Lond., 129: 421-430.
Booth, C., 1962. Some observations on behaviour of Cercopithecus monkeys. Ann. N.Y. Acad. Sei., 102:477-487.
Bopp, P., 1953. Zur Abhängigkeit der Inferioritätsreaktionen vom Sexualzyklus bei weiblichen Cynocephalen. Revue Suisse Zool., 60:441-447.
——, 1954. Schwanzfunktionen bei Wirbeltieren. Rev. Suisse Zool, 61:83-151.
——, 1962. Einige Beobachtungen über inferiores und sexuelles Verhalten bei Pavianen in Zoos. Zool. Garten, N.F., 26:278-283.
Boulenger, E. G., 1936. Apes and Monkeys. London: Harrap. 235 pp.
Bourlière, F., 1961. Patterns of social grouping among wild primates. In Social Life of Early Man. S. L. Washburn, ed., Chicago: Aldine, pp. 1-10.
——, J. J. Petter, and A. Petter-Rouseaux, 1956. Le dimorphisme sexual de la glande sous angulo-maxillaire d’Avahi laniger (Gmelin). Mém. Inst. Sei. Madagascar, Sér. A, 10:299-302.
Boutan, L., 1913. Le Pseudo-1anguage. Observations effectuées sur un anthropoide: le gibbon. Actes Soc. Linn. Bordeaux, 67:5-79.
Bowden, D., 1966. Primate behavioral research in the U.S.S.R. The Sukhumi Medico-Biological Station. Folia Primat., 4:346-360.
Brady, J. V., 1964. Behavioral stress and physiological change: a comparative approach to the experimental analysis of some psychosomatic problems. Trans. N.Y. Acad. Sei., 26:483-496.
——, and H. E. Rosvold, 1952. Influence of prefrontal lobotomy on social interaction in a monkey group. Psychosom. Med., 14:406-415.
Buettner-Janusch, J., 1964. The breeding of galagos in captivity and some notes on their behavior. Folia Primat., 2:93-110.
——, 1966. A problem in evolutionary systematics: nomenclature and classification of baboons, genus Papio. Folia Primat., 4:288-308.
——, and R. J. Andrew, 1962. The use of the incisors by primates in grooming. Amer. J. Phys. Anthrop., 20:127-130.
Busnel, R.-G., ed., 1963. Acoustic Behaviour of Animals. New York: Elsevier. 933 pp.
Butler, R. A., 1965. Investigative behavior. In Behavior of Nonhuman Primates. A. M. Schrier et al., eds. New York: Academic Press, pp. 463-493.
Buxton, A. P., 1952. Observations on the diurnal behaviour of the redtail monkey (Cercopithecus ascanius schmidti Matschie) in a small forest in Uganda. J. Anim. Ecol., 21:25-58.
Campbell, C. B. G., 1966. Taxonomie status of tree shrews. Science, 153:436.
Candler, G., 1903. Notes on the habits of the hoolock. Proc. Zool. Soc. Lond., 1:187-190.
Carmichael, L., 1965. Evaluation of certain modern techniques for the study of primate behavior in the wild. Proc. 73rd Ann. Conv. A. P. A., 111-112.
Carpenter, C. R., 1934. A field study of the behavior and social relations of howling monkeys (Alouatta palliata). Comp. Psychol. Monogr., 10:168 pp.
——, 1935. Behavior of red spider monkeys in Panama. J. Mammal., 16:171-180.
——, 1938. A survey of wildlife conditions in Atjeh, North Sumatra, with special reference to the orang-utans. Comm. No. 12. Netherlands Comm. Internatl. Nature Protection, pp. 1-34.
——, 1940. A field study in Siam of the behavior and social relations of the gibbon (Hylobates lar). Comp. Psychol. Monogr., 16, 212 pp.
——, 1942a. Societies of monkeys and apes. Biol. Symp., 8:177-204.
——, 1942b. Sexual behavior of free ranging rhesus monkeys (Macaca mulatta). I. Specimens, procedures and behavioral characteristics of estrus. II. Periodicity of estrus, homosexual, autoerotic and non-conformist behavior. J. comp. Psychol., 33:113-142, 143-162.
——, 1945. Concepts and problems of primate sociometry. Sociometry, 8:56-61.
——, 1952. Social behavior of non-human primates. Coll. Internatl. Centre Becher. Sei., 34:227-246.
——, 1958. Soziologie und Verhalten freilebender nichtmenschlicher Primaten. Handb. Zool. Berlin, 8:1-32.
——, 1962. Field studies of a primate population. In Roots of Behavior. Eugene L. Bliss, ed., New York: Harper & Bros., pp. 286-294.
——, 1964. Naturalistic Behavior of Nonhuman Primates. University Park: Pennsylvania State University Press, 454 pp.
Catchpole, H. R., and J. F. Fulton, 1939. Tarsiers in captivity. Nature, 144:514.
——, and, 1943. The oestrous cycle in Tarsius: observations on a captive pair. J. Mammal., 24:90-93.
Chance, M. R. A., 1955a. The agonistic social behaviour of Macaca mulatta. Brit. J. Anim. Behav., 3:35-36.
——, 1955b. The sociability of monkeys. Man, 176:1-4.
——, 1956. Social structure of a colony of Macaca mulatta. Brit. J. Anim. Behav., 4:1-13.
——, 1959. Structure of the social bond in primates. XVth Internatl. Congr. Zool. Proc., 860-862.
——, 1961. The nature and special features of the instinctive social bond of primates. In Social Life of Early Man. S. L. Washburn, ed., Chicago: Aldine, pp. 17-33.
——, and A. P. Mead, 1953. Social behaviour and primate evolution. Symp. Soc. Exp. Biol., 7:395-439.
Chu, E. H. Y., and M. A. Bender, 1961. Chromosome cytology and evolution in primates. Science, 133:1399-1405.
——, and B. A. Swomley, 1961. Chromosomes of lemurine lemurs. Science, 133:1925-1926.
Clark, W. E. LE Gros, 1924. Notes on the living tarsier (Tarsius spectrum). Proc. Zool. Soc. Lond., 217-223.
Clark, G., and H. G. Birch, 1945. Hormonal modifications of social behavior. I. The effect of sex hormone administration on the social status of a male castrate chimpanzee. Psychosom. Med., 7:321-329.
Collias, N., and C. Southwick, 1952. A field study of population density and social organization in howling monkeys. Proc. Amer. Philos. Soc., 96:143- 156.
Conaway, C. H., and C. B. Koford, 1965. Estrous cycles and mating behavior in a free-ranging band of rhesus monkeys. J. Mammal., 45:577-588.
Cook, N., 1939. Notes on captive Tarsius carbonarius. J. Mammal., 20:173-178.
Count, E. W., 1958. The biological basis of human sociality. Amer. Anthrop., 60:1049-1085.
Cowgill, U. M., 1964. Visiting in Perodicticus. Science, 146:1183-1184.
Crawford, M. P., 1940. The relation between social dominance and the menstrual cycle in female chimpanzees. J. Comp. Psychol., 30:483-513.
——, 1942. Dominance and social behavior, for chimpanzees, in a non-competitive situation. J. Comp. Psychol., 33:267-277.
Crook, J. H., and J. S. Gartlan, 1966. Evolution of primate societies. Nature, 210:1200-1203.
Cross, H. A., and H. F. Harlow, 1963. Observation of infant monkeys by female monkeys. Percept, mot. Skilh, 16:11-15.
Dalsgaard-Nielsen, T., 1944. Grasp reflex. Acta Psychiat. Neurol. Scand., KGh. 19:453-467.
Darwin, C., 1873. The Expression of the Emotions in Man and Animals. New York: Appleton, 374 pp.
Davenport, R. K., 1967. The orang-utan in Sabah. Folia Primat., 5:247-263.
——, 1876. Sexual selection in relation to monkeys. Nature, 15:18-19.
Delgado, J. M. R., 1963a. Effect of brain stimulation on task-free situations. In The Physiological Basis of Mental Activity. R. N. Peón, ed., pp. 260-280.
——, 1963b. Cerebral heterostimulation in a monkey colony. Science, 141:161-163.
——, 1964. Free behavior and brain stimulation. Internatl. Rev. Neurobiol., 6:349-449.
DeVore, I., 1962. The social behavior and organization of baboon troops. Doc. Diss. Dept. Anthrop., Univ. of Chicago. 182 pp.
——, 1963a. A comparison of the ecology and behavior of monkeys and apes. In Classification and Human Evolution. S. L. Washburn, ed., Chicago: Aldine, pp. 301-319.
——, 1963b. Mother-infant relations in free-ranging baboons. In Maternal Behavior in Mammals. H. L. Rheingold, ed. New York: Wiley, pp. 305-335.
——, ed., 1965a. Primate Behavior: Field studies of monkeys and apes. New York: Holt, Rinehart and Winston. 654 pp.
——, 1965b. Male dominance and mating behavior in baboons. In Sex and Behavior. F. A. Beach, ed., New York: John Wiley & Sons, pp. 266-289.
——, and S. L. Washburn, 1963. Baboon ecology and human evolution. In African Ecology and Human Evolution. F. C. Howell and F. Bourlière, eds. (Viking Fund Publ. Anthrop., No. 36). Chicago: Aldine, pp. 335-367.
Eibl-Eibesfeldt, I., 1953. Eine besondere Form des Duftmarkieren beim Riesen Galago, Galago crassicaudatus (E. Geoffroy 1812). Sangetierk. Mitt., 1:171- 173.
Ellefson, J. O., 1965. Territorial behavior in the common white-handed gibbon. Wenner-Gren Found. Symp. “Primate Social Behavior,” Sept. 2-12.
Emlen, J. T., 1962. The display of the Gorilla. Proc. Amer. Philos. Soc., 106:516- 519.
Etkin, W., 1963. Social behavioral factors in the emergence of man. Human Biol., 35:299-310.
Finch, G., 1942. Chimpanzee frustration responses. Psychosom. Med., 4:233-251.
Foley, J. P., Jr., 1934. First year development of a rhesus monkey (Macaca mulatta) reared in isolation. J. Genet. Psychol., 45:39-105.
——, 1935a. Judgement of facial expression of emotion in the chimpanzee. J. soc. Psychol, 6:31-67.
——, 1935b. Second year development of a rhesus monkey (Macaca mulatta) reared in isolation during the first eighteen months. J. Genet. Psychol, 47: 73-97.
Freedman, L. Z., and H. E. Rosvold, 1962. Sexual, aggressive and anxious behavior in the laboratory macaque. J. Nerv. Ment. Dis., 134:18-27.
Frisch, J. E., 1959. Research on primate behavior in Japan. Amer. Anthrop., 61:584-596.
——, 1963. Japan’s contribution to modem anthropology. In Studies in Japanese Culture. J. Roggendorf, ed., Tokyo: Sophia Univ., pp. 225-244.
Fulton, J. F., 1953. The limbic system: a study of the visceral brain in primates and man. Yale. J. Biol Med., 26:107-118.
Furuya, Y., 1961-62. The social life of silvered leaf monkeys (Trachypithecus cristatus). Primates, 3:41-60.
Garner, R. L., 1892. The Speech of Monkeys. New York: Webster. 217 pp.
Gillman, J., 1939. Some facts concerning the social life of Chacma baboons in captivity. J. Mammal, 20:178-181.
Goodall, J., 1963. Feeding behaviour of wild chimpanzees. Symp. Zool. Soc. Lond., 10:39-47.
——, 1964. Tool-using and aimed throwing in a community of free-1iving chimpanzees. Nature, 201:1264-1266.
——, 1965. New discoveries among African chimpanzees. Natl. Geogr., 128:802-831A.
Goodhart, C. B., 1964. A biological view of toplessness. New Sei., 23:558-561.
Goodman, M .,et al., 1965. Species and geographic differences in the transferrin polymorphism of macaques. Science, 147:884-886.
Goswell, M. J., and ]. S. Gartlan, 1965. Pregnancy, birth and early infant behaviour in the captive patas monkey Erythrocebus patas. Folia Primat., 3:189-200.
Goustard, M., 1961. La structure sociale d’une colonie de Macaca irus. Ann. Sei. Natur., Zool. Ser. 12, 3:287-322.
——, 1963. Introduction to the study of vocal communication in Macaca irus. Ann. Sei. Natur. Zool, 5:707-748.
Goy, R. W., and R. O. Dodsworth, 1962. Failure of early castration to prevent the development of masculine patterns of social behavior or the display of infantile sexual behavior by young rhesus males. Amer. Zool., 2:228.
——, and S. G. Eisele, 1964. Retention of copulatory ability after ovariectomy in a rhesus monkey. Anat. Ree., 148:373.
Gray, J. E., 1861. On the habits of the gorilla and other tailless long-armed apes. Proc. Zool. Soc. Lond., pp. 212-213.
Green, P. C., 1965. Influence of early experience and age on expression of affect in monkeys. J. Genet. Psychol., 106:156-171.
Gruner, M., and P. Krause, 1963. Biologische Beobachtungen an Weisspinselaffchen, Hapale jacchus L. 1758, im Berliner Tierpark. Zool. Garten, N. F., 28:108-114.
Haddow, A. J., 1951. Field and laboratory studies on an African monkey, Cercopithecus ascanius achmiditi Matschie. Proc. Zool. Soc. Lond., 122: 297-394.
Haldane, J. B. S., 1953. Animal ritual and human language. Diogenes, 4:61-73.
——, 1954. La signalisation animale. Ann. Biol., 30:89-98.
——, 1955. Animal communication and the origin of human language. Sei. Progr., 43:385-401.
Hall, K. R. L., 1960. Social vigilance behaviour of the Chacma baboon, Papio ursinus. Behaviour, 16:261-294.
——, 1962. The sexual, agonistic and derived social behaviour patterns of the wild Chacma baboon, Papio ursinus. Proc. Zool. Soc. Lond., 139:283-327.
——, 1963. Some problems in the analysis and comparison of monkey and ape behavior. In Classification and Human Evolution. S. L. Washburn, ed. Chicago: Aldine, pp. 273-300.
——, 1964. Aggression in monkey and ape societies. In The Natural History of Aggression. J. D. Carthy and F. J. Ebling, eds. London: Academic Press, pp. 51-64.
——, 1965a. Social organization of the old-world monkeys and apes. Symp. Zool. Soc. Lond., 14:265-289.
——, 1965b. Behaviour and ecology of the wild Patas monkey, Erythrocebus patas, in Uganda. J. Zool., 148:15-87.
——, 1965c. Ecology and behavior of baboons, patas and vervet monkeys in Uganda. In The Baboon in Medical Research. H. Vagtborg, ed. Austin: Univ. Texas, pp. 43-61.
——, 1965d. Experiment and quantification in the study of baboon behavior in its natural habitat. In The Baboon in Medical Research. H. Vagtborg, ed. Austin: Univ. Texas, pp. 29-42.
——, 1966. Social interactions of the adult male and adult females of a patas monkey group. In Social Communication among Primates, S. A. Altmann, ed., Chicago: University of Chicago Press, pp. 261-280.
——, R. C. Boelkins, and M. J. Goswell, 1965. Behaviour of patas monkeys, Erythrocebus patas, in captivity, with notes on the natural habitat. Folia Primat ., 3:22-49.
——, and I. DeVore, 1965. Baboon social behavior. In Primate Behavior. I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 53-110.
——, and J. S. Gartlan, 1965. Ecology and behaviour of the vervet monkey, Cercopithecus aethiops, Lolui Island, Lake Victoria. Proc. Zool. Soc. Lond., 145:37-56.
Hallowell, A. I., 1956. Structural and functional dimensions of a human existence. Quart. Rev. Biol., 31:88-101.
——, 1960. Self, society and culture in phylogenetic perspective. In Evolution after Darwin. S. Tax, ed. Chicago: Univ. Chicago Press, Vol. 2, pp. 309-371.
——, 1961. The procultural foundations of human adaption. In Social Life of Early Man. S. L. Washburn, ed. Chicago: Aldine, pp. 236-255.
Hamilton, G. V., 1914. A study of sexual tendencies in monkeys and baboons. J. Anim. Behav., 4:295-318.
Hampton, J. K., Jr., S. H. Hampton, and B. T. Landwehr, 1966. Observations on a successful breeding colony of the marmoset, Oedoipomidas oedipus. Folia Primat., 4:265-287.
Hansen, E. W., 1966. The development of maternal and infant behavior in the rhesus monkey. Behaviour, 27:107-149.
Harlow, H. F., 1962. Development of the second and third affectional systems in macaque monkeys. In Research Approaches to Psychiatric Problems. T. T. Tourlentes, S. L. Pollack, and H. E. Himwich, eds. New York: Grune and Stratton, pp. 209-229.
——, and M. K. Harlow, 1965. The affectional systems. In Behavior of Nonhuman Primates. A. M. Schrier et al., eds. New York: Academic Press, pp. 287-334.
Harrisson, B., 1962. Orang-utan. London: Collins.
——, 1963. A study of orang-utan behaviour in the semi-wild state. Internatl. Zoo Yearbk., 3:57-68. Hayes, K. J., 1950. Vocalizations and speech in chimpanzees. Amer. Psychol., 5:275.
——, and C. Hayes, 1954. The cultural capacity of chimpanzee. Human Biol., 26:288-303.
Hebb, D. O., 1945. The forms and conditions of chimpanzee anger. Bull. Canad. Psychol. Assoc., 2:32-35.
——, 1949. Temperament in chimpanzees: I. Method of analysis. J. Comp. Physiol. Psychol, 42:192-206.
——, and W. R. Thompson, 1954. The social significance of animal studies. In Handbook of Social Psychology. Gardner Lindzey, ed. 2 vols. Cambridge, Mass.: Addison-Wesley, vol. 1, pp. 532-561.
Hediger, H., and F. Zweifel, 1962. Primaten-ethologische Schnappschüsse aus dem Zürisher. Zoo. Bibl. Primat., 1:252-276.
Heinroth-Berger, K., 1959. Beobachtungen an handarfgezogen Mantelpavianen (Papio hamadryas L.). Z. f. Tierpsych., 16:706-732.
Herschberger, R., 1948. Adam’s Rib. New York: Pellegrini & Cudahy, 221 p. Hill, W. C. O., 1938. A curious habit common to lorisids and platyrrhine monkeys. Ceylon J. Sei., 321:66.
——, 1956. Behaviour and adaptations of the primates. Proc. Roy. Soc. Edinburgh, 66B:94-110.
——, 1953-1966. Primates: Comparative anatomy and taxonomy. Edinburgh: Univ. Press and New York: Interscience.
——, and A. N. Booth, 1957. Voice and larynx in African and Asiatic Colobidae. J. Bombay Nat. Hist. Soc., 54:309-321.
——, Porter, A., and M. D. Southwick, 1952. The natural history, endoparasites and pseudoparasites of . . . tarsiers. . . . Proc. Zool. Soc. Lond., 122:79-119.
Hinde, R. A., 1965. Rhesus monkey aunts. In Determinants of infant behavior. III. Proceedings of the third Tavistock Study Group on mother-infant interaction held at the house of the CIBA Found., Lond. Sept. 1963. B. M. Foss, ed. London: Methuen & Co., Ltd., pp. 67-75.
——, and T. E. Rowell, 1962. Communication by postures and facial expressions in the rhesus monkey (Macaca mulatta). Proc. Zool. Soc. Lond., 138:1-21.
——, ——, and Y. Spencer-Booth, 1964. Behaviour of socially living rhesus monkeys in their fisrt six months. Proc. Zool. Soc. Lond., 143:609-649.
——, Y. Spencer-Booth, and M. Bruce, 1966. Effects of 6-day maternal deprivation on rhesus monkey infants. Nature (Lond.), 210:1021-1023.
Hines, M., 1942. The development and regression of reflexes, postures and progression in the young macaque. Contrib. Embryol. Carneg. Inst., 196:155- 209.
Hockett, C. F., 1960. Logical considerations in the study of animal communication. In Animal Sounds and Communication. W. E. Lanyon and W. N. Tavolga, eds. Washington, D.C.: American Institute of Biological Sciences, pp. 392-430.
——, and R. Ascher, 1964. The human revolution. Cur. Anthrop., 5:135-168.
Hooff, J. A. R. A. M. van, 1962. Facial expressions in higher primates. Symp. Zool. Soc. Lond., 8:97-125.
Horel, J. A., F. R. Treichler, and D. R. Meyer, 1963. Coercive behavior in the rhesus monkey. J. Comp. Physiol. Psychol., 56:208-210.
Hornaday, W. T., 1879. On the species of Bornean orangs, with notes on their habits. Proc. Amer. Ass. Adv. Sei., 28:438-455.
Huber, E., 1931. Evolution of Facial Musculature and Facial Expression. Baltimore: Johns Hopkins Press; London: Oxford University Press. 184 pp.
Hutchinson, G. E., 1959. A speculative consideration of certain possible forms of sexual selection in man. Amer. Nat., 93:81-91.
——, 1963. Natural selection, social organization, hairlessness, and the australopithecine canine. Evolution, 17:558-559.
Hutchinson, R. R., N. H. Azrin, and D. F. Hake, 1966. An automatic method for the study of aggression in squirrel monkeys. J. Exp. Anal. Behav., 9:233-237.
Ilse, D. R., 1955. Olfactory marking of territory in two young male loris, Loris tardigradus lydekkerianus, kept in captivity in Poona. Brit. J. Anim. Behav., 3:118-120.
Imanishi, K., 1958. Societies and individuals: evolution of society and individuals. In Societies and Individuals in Animals. K. Imanishi, ed. Tokyo: Iwanami-Shoten.
Imanishi, K., 1960. Social organization of subhuman primates in their natural habitat. Curr. Anthrop., 1:393-407.
——, 1961. The origin of human family—A primatological approach. Jap. Ethnol., 25:119-130.
——, 1964. The individual in the society of Japanese monkeys. Japan Quart., 11:293-360.
Itani, J., 1951. Communication of the wild Japanese monkeys. Shizen, 6:45-49.
——, 1954. The Monkeys of Mt. Takasaki. Tokyo: Kobunsha, 284 p.
——, 1961. The society of Japanese monkeys. Japan Quart., 8:421-430.
——, 1963. Vocal communication of the wild Japanese monkey. Primates, 4:11-66.
Jacobsen, C. F., M. M. Jacobsen, and J. G. Yoshioka, 1932. Development of an infant chimpanzee during her first year. Comp. Psych. Mongr., 9:1-94.
Jay, P. C., 1962. The social behavior of the langur monkey. Doct. Diss. Dept. Anthrop., Univ. Chicago. 330 pp.
——, 1963a. The female primate. In Man and Civilization: The Potential of Woman. S. M. Färber and R. H. L. Wilson, eds. New York: McGraw-Hill, pp. 3-12.
——, 1963b. Mother-infant relations in langurs. In Maternal Behavior in Mammals. H. L. Rheinbold, ed., New York: Wiley, pp. 282-304.
——, 1965. The common langur of North India. In Primate Behavior. I. DeVore ed. New York: Holt, Rinehart and Winston, pp. 197-249.
Jensen, G. D., 1965. Mother-infant relationship in the monkey Macaca nemestrina: development of specificity of maternal response to own infant. J. Comp. Physiol. Psychol, 59:305-308.
——, and R. A. Bobbitt, 1965. On observational methodology and preliminary studies of mother-infant interaction in monkeys. Determinants of Infant Behav., 3:47-65.
——, ——, and B. N. Gordon, 1966. The development of mutual independence in mother-infant pigtailed monkeys, Macaca nemestrina. In Social Communication among Primates. S. A. Altmann, ed. Chicago: University of Chicago Press, pp. 43-53.
Jensen, G. D., and C. W. Tolman, 1962. Activity level of the mother monkey, Macaca nemestrina, as affected by various conditions of sensory access to the infant following separation. Anim. Behav., 10:228-230.
Jolly, A., 1966a. Lemur social behavior and primate intelligence. Science, 153: 501-506.
——, 1966b. Lemur Behavior: A Field Study in Madagascar. Chicago: University Press. 187 pp.
——, 1966c. Breeding synchrony in wild Lemur catta. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 3-14.
——, and L. A. Rosenblum, 1966. A behavioral taxonomy for macaques: based on laboratory observations of Macaca nemestrina and Macaca radiata.
Kaufmann, I. C. Primates, 7:205-258.
Kaufmann, J. H., 1965. A three-year study of mating behaviour in a free-ranging band of rhesus monkeys. Ecology, 46:500-512.
Kelemen, G., 1963. Comparative anatomy and performance of the vocal organ in vertebrates. In Acoustic Behavior of Animals. R.-G. Busnel, ed. Amsterdam: Elsevier, pp. 489-521.
Kelemen, G., and J. Sade, 1960. The vocal organ of the howling monkey (Alouatta palliata). J. Morph., 107:123-140.
Kempf, E. J., 1917. The social and sexual behavior of infra-human primates with some comparable facts in human behavior. Psychoanal. Rev., 4:127֊ 154.
Kern, J., 1964. Observations on the habits of the proboscis monkey, Nasalis larvatus Wurmb, made in the Brunei Bay area, Borneo. Zoologica, 49:183- 192.
——, 1965. The proboscis monkey. Anim. Kingd., 68:67-73.
Kirchshofer, R., 1960. Einige Verhaltensbeobachtungen an einem Guereza-Jungen Colobus polykomas kikuyuensis unter besonderer Berücksichtigung des Spiels. Z. f. Tierpsychol., 17:506-514.
——, 1962. Beobachtungen bei der Geburt eines Zwergschimpansen (Pan paniscus Schwarz 1929) und einige Bemerkungen zum Paarungsverhalten. Z. Tierpsychol., 19:597-606.
——, 1963. Einige bemerkenswerte Verhaltensweisen bei Saimiris im Vergleich zu verwandten Arten. Z. Morph. Anthrop., 53:77-91.
Klotz, M., 1966. Lautgebung bei Primaten. Wiss. Z. Humboldt-Univ. Berlin Math.-Nat. R., 15:23-56.
Klüver, H., and P. C. Bucy, 1937. “Psychic blindness” and other symptoms following bilateral temporal lobotomy on rhesus monkeys. Amer. J. Physiol., 119:352-353.
——, 1939. Preliminary analysis of functions of the temporal lobe in monkeys. Arch. Neurol. Psychiat., Chicago, 42:979-1000.
Kroeber, A. L., 1928. Sub-human culture beginnings. Quart. Rev. Biol., 3:325- 342.
Krumbiegel, I., 1962. Die Hamlynmeerkatze, Cercopithecus (Rhinostigma) hamlyni Pocock, 1907, als Mimikryfall. Säugetierkdl. Mitt., 10:22-24.
Kuehn, R. E., and W. C. Young, 1965. Mating behavior in adult Macaca mulatta. Amer. Zool., 5:687.
Kummer, H., 1956. Rang-Kriterien bei Mantelpavianen. Der Rang adulter Weibchen im Sozialverhalten, den Individualdistanzen und im Schla. Rev. Suisse Zool., 63:288-297.
——, 1957. Sociales Verhalten einer Mantelpaviangruppe. Beiheft zur Schweizerischen Zeitshrift für Psychologie und ihre Anwendungen. 91 pp.
——, 1967. Tripartite relations in hamadryas baboons. In Social Communication Among Primates. S. A. Altmann, ed., Chicago: University of Chicago Press, pp. 63-71.
——, 1968. Social organization of hamadryas baboons: a field study. Basel: Karger. 189 pp.
Kummer, H., and F. Kurt, 1963. Social units of a free-1iving population of hamadryas baboons. Folia Primat., 1:4-19.
——, and F. Kurt, 1965. A comparison of social behavior in captive and wild hamadryas baboons. In The Baboon in Medical Research. H. Vagtborg, ed. Austin: Univ. Texas Press, pp. 65-80.
Ladigina-Kohts, N. N., 1921. Report of the Zoöpsychological Laboratory of the Darwin Museum from 1914-1920. (In Russian.) Published by the Government. 15 pp.
Lahiri, R. K., and C. H. Southwick, 1966. Parental care in Macaca sylvana. Folia Primat., 4:257-264.
Lashley, K. S., and J. B. Watson, 1913. Notes on the development of a young monkey. J. Anim. Behav., 3:114-139.
Leary, R. W., and R. J. Maroney, 1962. The effect of home-cage environment on the social dominance of monkeys. J. Comp. Physiol. Psychol., 55:256- 259.
Lenneberg, E. H., 1964. A biological perspective of language. In New Directions in the Study of Language. E. H. Lenneberg, ed. Massachusetts: M.I.T. Press, pp. 65-88.
Lewis, G. C., 1939. Notes on a pair of tarsiers from Mindanao. J. Mammal., 20:57-61.
Lowther, F. DeL., 1940. A study of the activities of a pair of Galago senegalensis moholi in captivity including the birth and postnatal development of twins. Zoologica, 25:433-462.
Lucas, N. S., E. M. Hume, and H. H. Smith, 1937. On the breeding of the common marmoset (Hapale jacchus Linn.) in captivity when irradiated with ultra-violet rays. II. A ten years’ family history. Proc. Zool. Soc. Lond., A:205-211.
MacLean, P. D., 1958. The limbic system with respect to self-preservation and the preservation of the species. J. Nerv. Ment. Dis., 127:1-11.
——, 1959. The limbic system with respect to two basic life principles. In Central Nervous System and Behavior. M. A. Brazier, ed. Trans. 2nd Conf., N. Y., Josiah Macy, Jr. Foundation.
——, 1962. New findings relevant to the evolution of psychosexual functions of the brain. J. Nerv. Ment. Dis., 135:289-301.
——, and J. M. R. Delgado, 1953. Electrical and chemical stimulation of frontotemporal portion of limbic system in the waking animal. Electroenceph. Clin. Neurophysiol., 5:91-100.
——, D. Ploog, and B. W. Robinson, 1960. Circulatory effects of limbic stimulation, with special reference to the male genital organ. Physiol. Rev. 40:105-112.
Marier, P., 1961. The logical analysis of animal communication. J. Theoret. Biol., 1:295-317.
——, 1965. Communication in monkeys and apes. In Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, ed. New York: Holt, Rinehart & Winston, pp. 544-584.
——, 1966. Aggregation and dispersal: two functions in primate communication. In preparation.
Maroney, R. J., J. M. Warren, and M. M. Sinha, 1959. Stability of social dominance hierarchies in monkeys (Macaca mulatta). J. Soc. Psychol., 50:285- 293.
Maslow, A. H., 1935. The social behavior of monkeys and apes. Int. J. Indiv. Psychol., 1:47-59.
——, 1936a. The role of dominance in the social and sexual behavior of infra-human primates. I. Observations at Vilas Park Zoo. J. Genet. Psychol., 48:261-277.
——, 1936b. The role of dominance in the social behavior of infra-human primates: IV. The determination of hierarchy in pairs and in a group. J. Genet. Psychol., 49:161-198.
——, 1940. Dominance quality and social behavior in infra-human primates. J. Soc. Psychol., 2:313-324.
——, and S. Franzbaum, 1936. The role of dominance in social and sexual behavior of infra-human primates. II. An experimental determination of the behavior syndrome of dominance. J. Genet. Psychol., 48:278-309.
——, H. Rand and S. Newman, 1960. Some parallels between sexual and dominance behavior of infra-human primates and the fantasies of patients in psychotherapy, J. Nerv. Ment. Dis., 131:1-11.
Mason, J. W., and J. V. Brady, 1964. The sensitivity of psychoendocrine systems to social and physical environment. In Psychobiological Approaches to Social Behavior. P. H. Leiderman and D. Shapiro, eds. Palo Alto, Calif.: Stanford Univ. Press, pp. 4-23.
Mason, W. A., 1959. Development of communication between young rhesus monkeys. Science, 130:712-713.
——, 1960. The effects of social restriction on the behavior of rhesus monkeys: I. Free social behavior. J. Comp. Physiol. Psychol., 63:582-589.
——, 1961a. The effects of social restriction on the behavior of rhesus monkeys: II. Tests of gregariousness. J. Comp. Physiol. Psychol., 54:287-290.
——, 1961b. The effects of social restriction on the behavior of rhesus monkeys: III. Dominance tests. J. Comp. Physiol. Psychol, 54:694-699.
——, 1963. Social development of rhesus monkeys with restricted social experience. Percept. Motor Skills, 16:263-270.
——, 1964. Sociability and social organization in monkeys and apes. Advances exp. soc. Psychol, 1:277-305.
——, 1965a. Determinants of social behavior in young chimpanzees. In Behavior of Nonhuman Primates. A. M. Schrier, H. F. Harlow, and F. Stollnitz, eds. New York: Academic Press, pp. 335-364.
——, 1965b. Territorial behavior in Callicebus monkeys. Amer. Zool, 5:675.
——, 1966. Social organization of the South American monkey, Callicebus moloch: A preliminary report. Tulane Studies in Zoology, 13:23-28.
——, and G. Berkson, 1962. Conditions influencing vocal responsiveness of infant chimpanzees. Science, 137:127-128.
——, P. C. Green, and C. J. Posepanko, 1960. Sex differences in affective-social responses of rhesus monkeys. Behaviour, 16:74-83.
——, and J. F. Harlow, 1958. Learned approach by infant rhesus monkeys to the sucking situation. Psychol Rep., 4:79-82.
——, and J. H. Hollis, 1962. Communication between young rhesus monkeys. Anim. Behav., 10:211-221.
——, J. H. Hollis, and L. G. Sharpe, 1962. Differential responses of chimpanzees to social stimulation. J. Comp. Physiol. Psychol, 55:1105-1110.
——, S. V. Saxon, and L. G. Sharpe, 1963. Preferential responses of young chimpanzees to food and social rewards. Psychol Ree., 13:341-345.
——, and R. R. Sponholz, 1963. Behavior of rhesus monkeys raised in isolation. J. Psychiat. Res., 1:299-306.
Maxim, P. E., and J. Buettner-Janusch, 1963. A field study of the Kenya baboon. Amer. J. Phys. Anthrop., 21:165-180.
McCulloch, L. L., 1939. The role of clasping activity in adaptive behavior of the infant chimpanzee: I, II, III. J. Psychol, 7:283-316.
McKenna, M. C., 1966. Paleontology and the origin of the primates. Folia Primat., 4:1-25.
Meyer-Holzapfel, M., 1950. Beobachtungen über das Verhalten einer Gibbon familie im Zürcher Zoologische Garten. Zool. Garten (N.F.), 17:10-27.
Michael, R. P., 1965. Some aspects of the endocrine control of sexual activity in primates. Proc. Roy. Soc. Med., 58:595-598.
——, and J. Herbert, 1963. Menstrual cycle influences grooming behavior and sexual activity in the rhesus monkey. Science, 140:500-501.
Miller, G. S., 1928. Some elements of sexual behavior in primates and the possible influence on beginning of human development. J. Mammal, 9:273-279.
——, 1931. The primate basis of human sexual behavior. Quart. Rev. Biol., 6:379-410.
Miller, R. E., 1966. Experimental approaches to the physiological and behavioral concomitants of affective communication in rhesus monkeys. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 125-134.
——, J. V. Murphy, and I. A. Mirsky, 1959a, Nonverbal communication of affeet, J. Clin. Psychol., 15:155-158.
——, ——, and ——’ 1959b. Relevance of facial expression and posture as cues in communication of affect between monkeys. A. M. A. Arch. Gen. Psychiat. 1:480-488.
——, and J. H. Banks, Jr., 1962. The determination of social dominance in monkeys by a competitive avoidance method. J. Comp. Physiol. Psychol., 55:137-141.
——, ——, and H. Kuwahara, 1966. The communication of affects in monkeys: Cooperative reward conditioning. J. Genet. Psychol., 105:121-134.
Minnigerode, B., 1965. Functional and experimental investigations on phonation of the primates with special reference to the spontaneous muffling of the vocal cords during vibration. Arch. Ohr., Nas., u. Kehlkopfheilk., 184:403-410.
Mirsky, A. F., 1955. The influence of sex hormones on social behavior in monkeys. J. Comp. Physiol. Psychol., 48:327-335.
——, 1960. Studies of the effects of brain lesions on social behavior in Macaca mulatta: Methodological and theoretical considerations. Ann. N.Y. Acad. Sei., 85:785-794.
—— et al., 1953. Relation of adrenocortical and adaptive behavior. Psychosom. Med., 15:574-588.
——, H. E. Rosvold, and K. H. Pribram, 1957. Effects of cingulectomy on social behavior in monkeys. J. Neurophysiol., 20:588-601.
Mirsky, I. A., R. E. Miller, and J. Y. Murphy, 1958. The communication of affect in rhesus monkeys: I. An experimental method. J. Amer. Psychoanal. Assoc., 6:433-441.
Miyadi, B., 1965. Social life of Japanese monkeys. In Science in Japan. A. H. Livermore, ed. Washington, D.C.: A.A.A.S., pp. 315-334.
Monnier, M., 1946. L'organization des fonctions matrices chez les primates. Schweiz. Arch. Neurol. Psychiat., 56:233-238, 57:325-349.
Montagu, M. F. A., 1949. The origin and nature of social life and the biological basis of cooperation. J. Soc. Psychol., 29:267-283.
——, 1959. Natural selection and the origin and evolution of weeping of man. Science, 130:1572-1573.
Montagna, W., and R. A. Ellis, 1959. The skin of primates. I. The skin of the potto (Perodicticus potto). Amer. J. Phys. Anthrop., 17:137-162.
——, and J. S. Yun, 1963. The skin of primates. XVI. The skin of Lemur mongoz. Amer. J. Phys. Anthrop., 21:371-382.
Morris, D., ed., 1967. Primate Ethology. London: Weidenfeld & Nicolson. 374 pp.
Moszkowski, M., 1908. Biologische Notizen aus Zentralsumatra. S. B. Ges. naturf. Fr. Berlin, pp. 69-89.
Mowbray, J. B., and T. E. Cadell, 1962. Early behavior patterns in rhesus monkeys. J. Comp. Physiol. Psychol., 55:350-357.
Moynihan, M., 1964. Some behavior patterns of platyrrhine monkeys. I. The night monkey (Aotus trivirgatus).՝Smiths. Misc. Publ., 146:1-84.
——, 1966. Communication in Callicebus. In preparation.
Murphy, J. V., and R. E. Miller, 1956. The manipulation of dominance in monkeys with conditioned fear. J. Abnorm. Soc. Psychol., 53:244-248.
Narayan-Rao, C. R., 1927. Observations on the habits of Loris lydekkerianus. J. Mysore Univ., 1:57-62.
Nissen, H. W., 1931. A field study of the chimpanzee. Observations of chimpanzee behavior and environment in Western French Guinea. Comp. Psych. Monogr., 8, 122 pp.
——, 1951. Social behavior in primates. In Comparative Psychology. 3rd ed. C. P. Stone, ed. New York: Prentice-Hall. pp. 423-457.
——, 1958. Axes of behavioral comparison. In Behavior and Evolution. A. Roe and G. G. Simpson, eds. New Haven: Yale Univ. Press, pp. 183-205.
Nolte, A., 1955a. Freilandbeobachtungen über das Verhalten oon Macaca radiata in Südindien. Z. f. Tierpsychol., 12:77-87.
——, 1955b. Field observations on the daily routine and social behaviour of common Indian monkeys, with special reference to the bonnet monkey (Macaca radiata Geoffroy). J. Bombay Nat. Hist. Soc., 53:177-184.
——, 1958. Beobachtungen über das Instinktverhalten von Kapuzineraffen (Cebus apella L.) in der Gefangenschaft. Behaviour, 12:183-207.
——, and G. Dücker, 1959. Jugendentwicklung eines Kapuzineraffen (Cebus apella L.) mit besonderer Berücksichtigung des wechselseitigen Verhaltens von Mutter und Kind. Behaviour, 14:335-373.
Nowlis, V., 1941. Companionship preference and dominance in the social interaction of young chimpanzees. Comp. Psych. Monogr., 17, 57 pp.
Okano, T., 1965. Preliminary survey of the orang-utan in North Borneo (Sabah). Primates, 6:123-128.
Papez, J. W., 1937. A proposed mechanism of emotion. Arch. Neurol. Psychiat., 38:725-743.
Petter, J. J., 1959. L’observation des Lemuriens nocturnes dans les forêts de Madagascar. Utilisation des rayons I. R. Naturaliste malgache, 11:165-173.
——, 1962a. Ecological and behavioural studies of Madagascar lemurs in the field. Ann. N.Y. Acad. Sei., 102:267-281.
——, 1962b. Recherches sur l’ecologie et l’ethologie des lemuriens malgaches. Mem. Mus. Nat. Hist. Nat., Ser. A., 27, 146 pp.
——, 1965. The lemurs of Madagascar. In Primate Behavior, I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 292-319.
——, and A. Petter-Rousseaux, 1959. Contribution a l’étude du Aye-aye. Naturaliste malgache, 11:153-164.
——, and A. Petter, 1966. The aye-aye of Madagascar. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 195-205.
Ploog, D. W., 1963a. Vergleichend quantitative Verhaltensstudien an zwei Totenkipfaffen koloniën. Z. Morph. Anthrop., 53:92-108.
——, 1963b. Die Bedeutung der experimentellen Verhaltensforschung als Grundlagenwissenschaft für die klinische Psychiatrie. Jbk. 1963 der Max- Planck-Gesellschaft zur Förderung der Wissenschaften e.V., pp. 130-148.
——, 1964a. Vom limbischen System gesteuertes Verhalten. Der Nervenarzt, 4:166-174.
——, 1964b. Uber experimentelle Grundlagen der Gedächtnisforschung. Der Nervenarzt, 9:377-386.
——, 1964c. Verhaltensforschung und Psychiatrie. Psychiat. d. Gegenwart, 1/2B:291-443.
——, 1966. The behavior of squirrel monkeys (Saimiri sciureus) as revealed by sociometry, bioacoustics, and brain stimulation. In Social Communication among Primates. S. A. Altmann, ed., Chicago: University Chicago Press, pp. 149-184.
——, J. Blitz, and F. Ploog, 1963. Studies on social and sexual behavior of the squirrel monkey (Saimiri sciureus). Folia Primat., 1:29-66.
——, and P. D. MacLean, 1963. Display of penile erection in squirrel monkeys (Saimiri sciureus). Anim. Behav., 11:32-39.
Piveteau, J., 1961. Behavior and ways of life of the fossil primates. In Social Life of Early Man. S. L. Washburn, ed. Chicago: Aldine, pp. 11-16.
Plutchik, R., 1964. The study of social behavior in primates. Folia Primat., 2:67-92.
Pocock, R. I., 1939. Mammalia. In Fauna of British India, Wm. Thomas Blanford, ed. London: Taylor and Francis Vol. 1, 463 pp.
Pournelle, G., 1962. Observations on the birth and early development of Allen’s monkey. J. Mammal., 43:265-266.
Pribram, K. H., and M. M. Bagshaw, 1953. Further analysis of the temporal lobe syndrome utilizing frontotemporal ablations in monkeys. J. Comp. Neurol., 99:347-375.
Pumphrey, R. J., 1951. The Origin of Language: An Inaugural Lecture. Liverpool: Liverpool Univ. Press. 39 pp.
Ramaswami, I. S., and T. C. A. Kumar, 1965. Some aspects of reproduction of the female slender loris, Loris tardigradus lydekkerianus Cabr. Acta zool. (Stockholm), 46:257-273.
Révèsz, G., 1944. The language of animals. J. Genet. Psychol., 30:117-147.
Reynolds, V., 1963. An outline of the behaviour and social organization of forest-1iving chimpanzees. Folia Primat., 1:95-102.
——, 1965a. Some behavioral comparisons between the chimpanzee and the mountain gorilla in the wild. Amer. Anthrop., 67:691-706.
——, 1965b. Ecologie et comportement social des chimpanzés de la forêt de Budongo, Ouganda. Terre et la Vie, 111:155-166.
——, 1966. The social behaviour repertoire of rhesus monkeys (Macaca mulatta) in a captive colony. In preparation.
——, and F. Reynolds, 1965. Chimpanzees of the Budongo Forest. In Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 368-424.
Richter, C. P., 1931. The grasping reflex in the newborn monkey. Arch. Neurol. Psychiat., 26:784-790.
——, and M. Hines, 1932. Experimental production of the grasp reflex in adult monkeys by lesions of the frontal lobes. Amer. J. Physiol., 101:87-88.
——, and ——, 1934. The production of the “grasp reflex” in adult macaques by experimental frontal lobe lesions. Proc. Assoc. Nerv. Ment. Dis., 13:211-224.
Ripley, S., 1965. The ecology and social behavior of the Ceylon gray langur, Presbytis entellus thersites. Doc. Diss. Univ. of Calif., Berkeley.
——, 1966. Intertroop encounters among Ceylon gray langurs (Presbytis entellus). In Social Communication Among Primates. S. A. Altmann, ed. Chicago: University of Chicago Press, pp. 135-147.
Roberts, D., 1966. Lemurs and grooming. New Scientist, 30:260.
Robinson, B. W., 1966. Neurological aspects of evoked vocalizations. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press.
Robinson, S. M., 1925. Birth of a white-handed gibbon (Hylobates lar) in captivity. J. Bombay Nat. Hist. Soc., 30:456-458.
Rodriguez-Delgado, R., and J. M. R. Delgado, 1962. An obective approach to measurement of behavior. Philosophy Sei., 29:253-268.
Rohles, F. H., 1962. The Chimpanzee: A topical bibliography. New Mexico: Holloman, A. F. B. 312 pp.
——, 1963. ibid. Addenda. 28 pp.
Rosenblum, L. A., and I. C. Kaufmann, 1966. Laboratory observations of early mother-infant relations in pigtail and bonnet macaques. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 133-141.
——, ——, and A. J. Stynes, 1966. Some characteristics of adult social and autogrooming patterns in two species of macaque. Folia Primat., 4:438-451.
Rosvold, H. E., A. F. Mirsky, and K. H. Pribram, 1954. Influence of amygdalectomy on social behavior in monkeys. J. Comp. Physiol. Psychol., 47:173-178.
Rowell, T. E., 1961. The social development of some rhesus monkeys. In Determinants of Infant Behaviour. II. B. M. Foss, ed. London: Methuen & Co. Ltd. pp. 35-49.
——, 1962. Agonistic noises of the rhesus monkey (Macaca mulatta). Symp. zool. Soc. Lond., 8:91-96.
——, 1963. Behaviour and female reproductive cycles of rhesus macaques. J. Reprod. Fertil., 6:193-203.
——, 1965. Some observations on a hand-reared baboon. In Determinants of infant behaviour. III. B. M. Foss, ed. London: Methuen & Co., Ltd., pp. 77-84.
——, 1966a. Female reproductive cycles and the behavior of baboons and rhesus macaques. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 15-32.
——, 1966b. Forest living baboons in Uganda. J. Zool. 149:344-364.
——, and R. A. Hinde, 1962. Vocal communication by the rhesus monkey (Macaca mulatta). Proc Zool. Soc. Lond., 138:279-294.
——, ——, and Y. Spencer-Booth, 1964. “Aunt”-infant interaction in captive rhesus monkeys. Anim. Behav., 12:219-226.
Ruch, T. C., 1941. Bibliographica Primatologica. Springfield, Illinois: Thomas. 241 pp.
Ruesch, ]., 1953. Synopsis of the theory of human communication. Psychiatry, 16:215-243.
Rumbaugh, D. M., 1965. Maternal care in relation to infant behavior in the squirrel monkey. Psychol. Rep., 16:171-176.
Russell, C., and W. M. S. Russell, 1961. Human Behavior, a new approach. New York, Little, Brown & Co. 532 pp.
Sackett, G. P., 1965a. Response of rhesus monkeys to social stimulation presented by means of colored slides. Percept. Motor Skilh, 20:1027-1028.
——, 1965b. Effects of rearing conditions upon the behavior of rhesus monkeys (Macaca mulatta). Child Develop., 36:855-868.
Sahlins, M. D., 1959. The social life of monkeys, apes and primitive man. In The Evolution of Man’s Capacity for Culture. J. D. Spuhler, ed. Detroit: Wayne State Univ, pp. 54-73.
Sanderson, I. T., 1937. Animal Treasure. New York: Viking Press 325 pp.
——, 1940. The mammals of the north Cameroon forest area. Trans. Zool. Soc. Lond., 24:623-725.
Saver, E. G. F., and E. M. Sauer, 1963. The South West African bush-baby of the Galago sensgalensis group. J. Sth. West. Afr. Sei. Soc., Windhoek, 16:5-36. Schaller, G. B., 1961. The orang-utan in Sarawak. Zoologica, 46:73-82.
——, 1963. The Mountain Gorilla: Ecology and behavior. Chicago: Univ. Chic. Press. 431 pp.
——, 1965a. The behavior of the mountain gorilla. In Primate Behavior. I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 324-367.
——, 1965b. Field procedures. In Primate Behavior: Field Studies of Monkeys and Apes. I. Devore, ed. New York: Holt, Rinehart and Winston, pp. 623- 629.
——, and J. T. Emlen, Jr., 1963. Observations on the ecology and social behavior of the mountain gorilla. In African Ecology and Human Evolution. F. C. Howell and F. Bourlière, eds. Chicago: Aldine, pp. 368-384.
Schenkel, R., 1964. Zur Ontogenesis des Verhaltens bei Gorilla und Mensch. Z. Morph. Anthrop., 54:233-259.
Schmidt, M., 1878. Beobachtungen am Orang-utan. Zool. Gart., Frankfurt, 19:193-198.
Schrier, A. M., H. F. Harlow, and F. Stollnitz, 1964. Behavior of Nonhuman Primates. New York: Academic Press 595 pp.
Schultz, A. H., 1961. Some factors influencing the social life of primates in general and of early man in particular. In Social Life of Early Man. S. L. Washburn, ed. Chicago: Aldine, pp. 58-90.
Seay, B., 1966. Maternal behavior in primiparous and multiparous rhesus monkeys. Folia Primat., 4:146-168.
——, E. Hansen, and H. F. Harlow, 1962. Mother-infant separation in monkeys. J. Child Psychol. Psychiat., 3:123-132.
——, B. K. Alexander, and H. F. Harlow, 1964. Maternal behavior of socially deprived rhesus monkeys. J. Abnorm. Soc. Psychol., 69:345-354.
——, and H. F. Harlow, 1965. Maternal separation in the rhesus monkey. J. Nerv. Ment. Dis., 140:434-441.
Sebeok, T. A., 1962. Coding in the evolution of signaling behavior. Behav. Sei., 7:430-442.
——, 1965a. Animal communication. Science, 147:1006-1014.
——, 1965b. [Comments on language and communication.] In the Origin of Man. P. L. DeVore, ed. New York: Wenner-Greer Foundation, pp. 86-88.
——, A. S. Hayes, and M. C. Bateson, 1964. Approaches to Semiotics. The Hauge: Mouton. 294 pp.
Service, E. R., 1962. Primitive Social Organization. New York: Random House. 211 pp.
Shilling, C. W. (project director), 1964. The Baboon: An Anecdotal Bibliography. San Antonio, Texas: The Southwest Foundation for Research and Education. 642 pp.
Simonds, P. E., 1965. The bonnet macaque in South India. In Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 175-196.
Simpson, G. G., 1945. The principles of classification and a classification of mammals. Bull. Amer. Mus. Nat. Hist., 85:1-350.
Southwick, C. H., 1962. Patterns of intergroup social behavior in primates, with special reference to rhesus and howling monkeys. Ann. N.Y. Acad. Sei., 102:436-454.
——, 1963. Primate Social Behavior. Princeton: Van Nostrand. 192 pp.
——, and M. A. Beg, 1961. Social behavior of rhesus monkeys in a temple habitat in northern India. Amer. Zool., 1:262.
Spencer-Booth, Y., R. A. Hinde, and M. Bruce, 1965. Social companions and the mother-infant relationship in rhesus monkeys. Nature, 208:301.
Stark, D., and R. Schneider, 1960. Larynx. In Primatologia: Handbook of Primatology. H. Hofer, A. H. Schultz, and D. Stark, eds. Vol. 3. Basel & New York: S. Karger, pp. 423-587.
Stein, M. R., 1936. The myth of the lemurs comb. Amer. Nat., 70:19-28.
Steinbacher, G., 1940. Geburt und Kindheit eines Schimpansen. Z. Tierpsychol., 4:188-203.
Stott, K., Jr., and C. J. Selsor, 1961. Observations of the maroon leaf monkey, Presbytis rubicunda, in North Borneo. Mammalia, 25:184-189.
Struhsaker, T. T., 1965. Behavior of the vervet monkey (Cercopithecus aethiops) Doc. Diss., Univ. of Calif. (Berkeley). 306 pp.
——, 1966. Auditory communication among vervet monkeys (Cercopithecus aethiops). In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 281-384.
Sugiyama, Y., 1964. Group composition, population density and some sociological observations of hanuman langurs (Presbytis entellus). Primates, 5:7-37.
——, 1965a. Behavioral development and social structure in two troops of hanuman langurs (Presbytis entellus). Primates, 6:213-247.
——, 1965b. Bibliography of the study of primate behavior in Japan. In Japanese Monkeys. Stuart A. Altmann, ed. Atlanta, Yerkes Regional Primate Research Center. Stuart Altmann, pp. 141-151.
——, 1966. Social organization of hanuman langurs. In Social Communication among Primates. S. A. Altmann, ed. Chicago: Univ. Chicago Press, pp. 221- 236.
——, K. Yoshiba, and M. D. Pathasarathy, 1965. Home range, mating season, male group and inter-group relations in hanuman langurs (Presbytis entellus). Primates, 6:73-106.
Takeshita, H., 1961-1962. On the delivery behavior of squirrel monkeys (Saimiri sciurea) and a Mona monkey (Cercopithecus mona). Primates, 3:59-72.
Tanaka, J., 1965. Social structure of Nilgiri langurs. Primates, 6:107-122.
Taub, E., S. J. Ellman, and A. J. Berman, 1966. Deafferentation in monkeys: Effect on conditioned grasp response. Science, 151:593-594.
Thompson, N. S., 1965. The effects of acquaintance in iris macaques. Amer. Zool., 5:676.
Tinklepaugh, O. L., 1933. Le comportment sexual chez les chimp auzés et les signes inférieurs considéré comme une réaction de substitution consécutive a des troubles émotionelles. J. Psychol. Norm. Path., 30:930-954.
——, and C. G. Hartman, 1932. Behavior and maternal care of the newborn monkey (Macaca mulatta = “M. rhesus”). J. Genet. Psychol., 40:257-286.
Tokuda, K., 1961-1962. A study on the sexual behavior in the Japanese monkey troop. Primates, 3:1-40.
Tomilin, M., and R. M. Yerkes, 1935. Chimpanzee twins: behavioral relations and development. J. Genet. Psychol., 46:239-263.
Turner, W. J., 1957. Some phylogenetic roots of human behavior. Trans. N.Y. Acad. Sei., 20:192-198.
Ullrich, W., 1961. Zur Biologie und Soziologie der Colobusaffen (Colobus guereza caudatus Thomas 1885). Zool. Gart. (N.F.), 25:305-368.
——, 1964. Einige Verhaltensweisen der Kattas (Lemur catta L. ). Zool. Gart., 29:1-4.
Ulmer, F. A., Jr., 1963. Observations on the Tarsier in captivity. Zool. Gart. 27:106-121.
Vandenbergh, J. G., 1966. Behavioral observations of an infant squirrel monkey. Psychol. Rep., 18:683-688.
VanValen, L., 1965. Treeshrews, primates, and fossils. Evolution, 19:137-151.
Voss, H., 1955. Bibliographie der Menschenaffen . . . Jena: G. Fischer. 163 pp.
Walker, A. E., A. F. Thomson, and J. D. McQueen, 1953. Behavior and the temporal rhinencephalon in the monkey. Johns Hopkins Hosp. Bull., 93:65-93.
Walker, E. P., et al, 1964. Mammals of the World. Vol. 1. Baltimore: Johns Hopkins Press. 644 pp. Wallace, A. R., 1856a. On the habits of the orang-utan of Borneo. Ann. Mag. Nat. Hist., 18:26-32.
——, 1856b. Some accounts of an infant “orang-utan.” Ann. Mag. Nat. Hist., 17:386-390.
Warren, J. M., and R. J. Maroney, 1958. Competitive social interaction between monkeys. J. Soc. Psychol., 48:223-233.
Washburn, S. L., 1963a. Behavior and human evolution. In Classification and Human Evolution. S. L. Washburn, ed. Chicago: Aldine, pp. 190-203.
——, ed., 1963b. Social life of early man. (Viking Fund Publications in Anthropology No. 31) Chicago: Aldine. 312 pp.
——, and I. DeVore, 1961. Social behavior of baboons and early man. In Social Life of Early Man. S. L. Washburn, ed. Chicago: Aldine, pp. 91-105.
——, and D. A. Hamburg, 1965. The study of primate behavior. In Primate Behavior, I. DeVore, ed. New York: Holt, Rinehart and Winston, pp. 1-13.
——, and F. C. Howell, 1960. Human evolution and culture. In Evolution after Darwin. Sol Tax, ed. Chicago: Univ. Chicago Press, Vol. 2, pp. 33-56.
——, P. C. Jay, and J. B. Lancaster, 1965. Field studies of old world monkeys and apes. Science, 150:1541-1547.
Wharton, C. H., 1950. The tarsier in captivity. J. Mammal, 31:260-268.
Yerkes, R. M., 1933a. Genetic aspects of grooming, a socially important primate behavior pattern. J. Soc. Psychol, 4:3-25.
——, 1933b. A resume of three lectures on “Social relations in monkey, ape and man.” Bull. Wagner Inst. Sei., Philadelphia, 8:66-71.
——, 1934. Suggestibility in chimpanzee. J. Soc. Psychol, 5:271-282.
——, 1936. A chimpanzee family. J. Genet. Psychol, 47:362-370.
——, 1939. Sexual behavior in the champanzee. Human Biol, 11:78-111.
——, 1943. Champanzees. A laboratory colony. New Haven: Yale Univ. Press. 321 pp.
——, and J. H. Elder, 1936. Oestrus, receptivity, and mating in chimpanzee. Comp. Psych. Monographs, 13, 39 pp.
——, and B. W. Learned, 1925. Chimpanzee Intelligence and Its Vocal Expression. Baltimore: Williams and Wilkins. 157 pp.
——, and M. Tomlin, 1935. Mother-infant relations in chimpanzees. J. Comp. Psychol, 20:321-359.
——, and A. W. Yerkes, 1935. Social behavior in infra-human primates. In A Handbook of Social Psychology. Worcester, Mass.: Clark Univ. Press. 1195 pp.
Young, W. C., and W. D. Orbison, 1944. Changes in selected features of behavior in pairs of oppositely sexed chimpanzees during the sexual cycle and after ovariectomy. J. Comp. Psychol, 37:107-143.
Zhinkin, N. I., 1963. An application of the theory of algorithms to the study of animal speech: methods of vocal intercommunication between monkeys. In Acoustic Behaviour of Animals. R.-G. Busnel, ed. Amsterdam: Elsevier, pp. 132-180.
Zuckerman, S., 1929. The social life of the primates. Realist, 1:72-88.
——, 1932. Social Life of Monkeys and Apes. London: Kegan Paul and New York: Harcourt, Brace. 357 pp.
——, 1933. Functional Affinities of Man, Monkeys and Apes. London: Kegan Paul 203 p.
——, 1944. The influence of hormones of man’s social evolution. Endeavour, 3:80-83.
——, 1952. L’hominisation de la famille et des groupes sociaux. In Les Processus de l’hominisation. Paris, Centre National de la Recherche Scientifique. 213 pp.