Carpenter, Clarence Ray

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(b. Lincoln County, North Carolina, 28 November 1905: d. Athens, Georgia, 1 March 1975), primatology, field studies, Cayo Santiago Rhesus Colony.

Carpenter’s research of wild primate behavior during the 1930s was, and continued to be in the early 2000s, widely recognized within the primatological community as the first scientific primate field studies. Carpenter demonstrated that prolonged and accurate observation of primate behavior was possible and set forth methods with which to accomplish fieldwork. In turn, Carpenter encouraged the blossoming of field primatology, and indeed field studies of animal behavior more broadly, which occurred after World War II. He was also a key contributor to the formation of Cayo Santiago Rhesus Colony, an island-based field site in Puerto Rico designed for efficient observation of natural primate behavior. The colony continued to be a significant site for long-term primate research into the twenty-first century.

Carpenter and Robert M. Yerkes . After receiving his master’s degree in 1929 from Duke University, Carpenter completed his PhD in 1931 working with Calvin P. Stone at Stanford University. At Stanford, Carpenter studied the sexual behavior of pigeons and its connections with physiology. This research involved gonadectomy, utilized still and motion pictures, and was funded by the National Research Council Committee for Research in the Problems of Sex (NRC-CRPS).

Carpenter’s graduate work earned him a reputation for being an excellent observer, a skill that psychobiologist Robert M. Yerkes was seeking in order to extend the series of naturalistic studies of primate behavior that he had initiated in 1929. In 1931, Carpenter moved to New Haven to work with Yerkes as a fellow at Yale Laboratories of Primate Biology. Yerkes’s research focused on laboratory studies of primate behavior; however, he was also a strong advocate of fieldwork due to its ability to gain knowledge of primate social behavior and to enable comparison of captive, artificial behaviors with those that occurred in nature.

For this reason, Yerkes sponsored a series of studies of wild primate behavior during the late 1920s and early 1930s. The first of these studies was conducted by Harold Bingham in 1929. This project took place in the National Parc Albert in the Belgian Congo and attempted to observe gorilla behavior in the wild. Unfortunately, insufficient field methods, lack of field experience, and the shy demeanor of gorillas resulted in few observations of gorilla behavior. During the same year, Yerkes organized Henry Nissen’s field study of chimpanzees at the Pasteur Institute of Kindia in Western Africa. Nissen was more successful than Bingham at observing wild primates but also failed to gain sufficient data to make conclusions about primate social behavior.

It was within the context of these previous studies, both of which had demonstrated the need for new and improved field methods with which to make prolonged observations of primate behavior, that Carpenter joined the Yale Laboratories of Primate Biology.

Fieldwork . Carpenter continued Yerkes’s series of naturalistic studies of primate behavior by spending a total of nearly eight months between 1931 and 1933 at Barro Colorado, an island in Puerto Rico. It was at this time in his career that Carpenter married his first wife, Mariana, with whom he had two sons, Richard and Lane. During his Barro Colorado fieldwork, Carpenter used his skills as an observer and existing methods of habituation to make prolonged observations of natural howler behavior, including communication, territoriality, and social interactions. These extensive observations demonstrated coordination within and between groups of howlers, including the use of vocalizations to exercise social control and to avoid intergroup aggression. Carpenter also examined howlers’ locomotion and posturing, including how their feet and prehensile tail facilitated their arboreal nature. Relationships between howlers and their environment were also studied, particularly howlers’ interactions with other species. It was this kind of approach to primate research that would eventually develop into what became known as behavioral ecology.

While in Barro Colorado, Carpenter also developed new field techniques. He observed and described complex social relationships, for example, with what would become known as the dyadic method. This technique involved breaking down a social situation into its component parts. All possible relationships would be observed and described in turn, including those between males, females, and juvenile group members. Carpenter also developed a counting procedure with which to make an accurate census of the Barro Colorado howler population, thus overcoming a barrier that had marred many studies of wild animal populations.

The length and accuracy of Carpenter’s observations and his ability to census primate populations ensured that his fieldwork formed a strong contrast to past primate studies. This was true for his howler study at Barro Colorado and equally so for his study of gibbons in Thailand during the Asiatic Primate Expedition in 1937. The main members of the expedition team were Harold Coolidge of the Museum of Comparative Zoology at Harvard University, Adolph H. Schultz of the Department of Anatomy at Johns Hopkins University, and Carpenter, who at that time was an assistant professor and lecturer at Bard College. Coolidge, Schultz, and Carpenter were also accompanied by Sherwood Washburn, a graduate student of Earnest Hooton at Harvard, who would go on to become a prominent anthropologist. During this expedition, Carpenter continued to emphasize the need for repetition and accuracy in field observations, an element of his fieldwork he extended by using recording technology and playback techniques to ensure precise descriptions of gibbon vocalizations and to determine the functions these calls served in primate groups.

In addition to examining gibbon vocalizations, Carpenter pursued similar questions to those he had explored during his howler research in Barro Colorado. Once again, he described both individual and group behavior and particularly focused on social coordination and control within and between groups. He also continued to study the role of territoriality in primate behavior, a topic connected to his work on vocalizations and social stability. The results of Carpenter’s gibbon research were published in his 1940 monograph, which also contained an interesting introduction by Adolph H. Schultz, who proposed that gibbons were evolutionarily closer to humans than any species of monkey and thus deserved to be classified among the “higher primates.” This concept was also echoed by Carpenter in the body of the monograph.

The significance of Carpenter’s intellectual contributions to primate research was matched, if not exceeded, by his development of new and existing field methods. Earlier fieldwork had been criticized for producing anecdotal and unreliable observations rather than scientific research. Carpenter’s work at Barro Colorado and during the Asiatic Primate Expedition developed new techniques with which to apply scientific standards of repetition and accuracy to primate fieldwork thus demonstrating field studies could indeed be scientific.

Primatologists Shirley Strum and Linda Fedigan have summarized Carpenter’s multiple methodological contributions to primatology as follows: “Carpenter set a new and lasting standard for data collection. He clarified and pioneered methods of habituation for wild primates, made explicit the standards for the acceptance of naturalistic observations as facts, and developed a new approach to the analysis of complex social interactions” (p. 9). Carpenter ensured accuracy in his observations and counts by applying strict standards of repetition and note taking. He and others used this element of his fieldwork to promote the scientific value of the field during much of the early to mid-twentieth century.

Between 1930 and 1950 Carpenter frequently used his publications and speeches to discuss the ways in which fieldwork could contribute to primate research and animal behavior studies more broadly. In these public forums, Carpenter presented the laboratory and field as supplementary, each with contrasting advantages and limitations. During this period, the scientific value of the laboratory for animal behavior studies went virtually unquestioned while the potential contributions of the field had yet to be widely recognized by the scientific community.

Carpenter highlighted the specific research questions that could, and should, be pursued in the field. In his 1940 monograph concerning his gibbon research during the Asiatic Primate Expedition, Carpenter stated that: “There are problems ... which can best be investigated by means of field procedures, in fact, they cannot be validly studied except by observing free ranging animals. Studies of seasonal and diurnal variation in behavior, grouping patterns and inter-group relations and communicative behavior are some of the subjects which may first and most validly be studied in the natural habitat of the animals” (p. 29). Such specific examples were consistently embedded in Carpenter’s broader view of the laboratory and field as places of equal scientific value and beholden to the same scientific standards. In 1950, he summarized this viewpoint in an article based on a conference he attended in 1948 concerning field methodology and techniques and published in Annals of the New York Academy of Sciences: “Let there be no mistake, in the scientific courts of appeal, we must expect all evidence, from laboratory and field, to be weighed in the same critical scales and judged by the same criteria” (p. 1008).

Yerkes also used Carpenter’s work to present the laboratory and field as supplementary and to highlight the limitations of captive studies and the contrasting advantages of the field. In 1935, for example, Yerkes and his wife Ada spent several pages critiquing Solly Zuckerman’s study of captive primates on “Monkey Hill” at the London Zoological Gardens due to the artificiality of the behaviors observed there. They contrasted Zuckerman’s study directly with Carpenter’s fieldwork and used Carpenter’s research to exemplify how natural primate behavior could be observed in the wild. Beyond primate studies, researchers of animal behavior, such as Theodore C. Schneirla of the Department of Animal Behavior at the American Museum of Natural History, presented Carpenter’s fieldwork as proof of the value of field studies and the ability of such work to fulfill scientific standards of accuracy and repeatability.

The efforts made by Carpenter, Yerkes, and others to promote the scientific value of fieldwork during the 1930–1950 period played a significant role in the growth in fieldwork that occurred after World War II. They also contributed to a gradual recasting of the field as a place for science rather than simply a location where amateur naturalists made anecdotal and uncritical observations of animal behavior. A negative conception of fieldwork had been formed over many years, initially through exaggerated claims in travel and adventure literature concerning encounters with wild animals, such as those made by amateur naturalist Paul du Chaillu. During the twentieth century, and arguably true in the early 2000s, such negative conceptions of the field were fueled by continuing false assumptions, including an association of the field with adventure rather than science.

Cayo Santiago Rhesus Colony . Despite the value Carpenter assigned to the field, he became increasingly frustrated with what he saw as the inefficiency of fieldwork after his experiences during the Asiatic Primate Expedition. For this reason, he helped to establish an island-based primate colony on Santiago Island, Puerto Rico, between 1938 and 1940. This site would become a significant location for long-term primate research. Researchers such as Peter Marler have identified its establishment as Carpenter’s central contribution to primatology.

Carpenter established the colony by transporting approximately four hundred rhesus macaques from India to Santiago Island. These primates were to serve a dual purpose by providing the opportunity to observe natural primate behavior while establishing a regenerating supply of rhesus monkeys for biomedical experiments. As such, Santiago Island represents the dramatic rise in demand for primates occurring in biomedicine during this period and the increasing restrictions placed on the exportation of primates from India. Such restrictions were imposed by the Indian government and encouraged by animal rights groups such as the Society for the Prevention of Cruelty to Animals. The island also represents one example of Carpenter’s personal concern about primate supply for experimentation, a concern also reflected in his involvement during the 1950s in the Non-human Primate Committee of the Institute of Animal Resources, a branch of the Biology and Agriculture Division of the National Research Council.

After Cayo Santiago Rhesus Colony was established, Carpenter conducted research on the island, primarily focusing on the reproductive behavior of rhesus macaques. His work on the island moved away from the broadly noninterventionist approach adopted during his work in Barro Colorado and Thailand. On Santiago Island, for example, he removed the alpha male to mimic the death of an alpha in nature, thus enabling the rapid observation of an event that would potentially take years to occur without such intervention. After the removal of the alpha male, he observed how the group regained social stability.

Donna Haraway’s work concerning Carpenter focused on this research, along with Carpenter’s study of communication during the Asiatic Primate Expedition. Haraway interpreted Carpenter’s application of such interventionist techniques as evidence of his emphasis of social control, a concern prevalent in American society during the early to mid-twentieth century. Carpenter certainly approached his study of communication, at least in part, with a focus on social control and related his conclusions to human behavior.

In contrast to Haraway’s work, Montgomery uses the analytical categories of place and practice to examine Carpenter’s methodological contributions to primatology and his understanding of concepts such as naturalness. Carpenter’s howler and gibbon field studies, for example, emphasized avoidance of modification in order to ensure observations of natural behavior. In his 1940 monograph concerning his work during the Asiatic Primate Expedition, for example, he wrote: “The methodological problem was that of directly observing a representative sampling of individuals and groups for long periods of time in their undisturbed natural habitat and of accurately recording and reporting the observations Everything possible was done to secure records of the gibbons’ free, natural, undisturbed behavior and of their social responses and relationships” (p. 33, italics in original). Carpenter’s application of interventionist methods on Santiago Island thus formed a clear departure from his past focus on observing behavior as it would occur without interference by the observer. Carpenter’s laboratory experience while at graduate school and his concerns about the lack of scientific status for fieldwork helps to explain this shift towards increasingly interventionist field practices. Interestingly, Carpenter continued to identify behaviors observed on Santiago Island as natural despite his increasing application of interventionist techniques. This allowed Carpenter to continue to promote fieldwork on the grounds that it provided a unique opportunity to study natural behavior. For a more detailed account of the ways in which Carpenter defined naturalness during his career, and the complexity behind his transition from noninterventionist to interventionist field practices, see Montgomery’s dissertation and article.

Carpenter’s long-term involvement in Cayo Santiago Rhesus Colony, however, was not in terms of his research but rather through his direct and indirect administrative roles. He remained in contact with researchers working on the island and during the 1970s served as a member of the Caribbean Primate Research Center (CPRC). This group was established on 1 July 1970 by the University of Puerto Rico and the National Institute of Neurological Disorders and Strokes (NINDS), which had gained control of the island colony. The CPRC included Cayo Santiago Rhesus Colony and primate groups in three other tropical locations and thus demonstrates the increasingly international nature of primate research during the last three decades of the twentieth century. It was this international aspect of primatology that Carpenter took particular efforts to embrace later in his career when his focus increasingly shifted from performing primate fieldwork to a range of administrative roles.

Other Scientific Contributions . After working on Barro Colorado, Carpenter worked at Pennsylvania State University in several capacities until 1970. He was originally employed as a psychology professor, was promoted to chair of the Psychology Department from 1952 to 1956, and was then moved to various education-based programs to focus on the use of technology in education from 1957 to 1965. In 1965, he returned to the Psychology Department, this time as a research professor for both the Psychology and Anthropology departments. These career changes reflect Carpenter’s enduring interest in technology as a means of improving primate research and education alike and the multidisciplinary nature of primatology. They also exemplify Carpenter’s increasing preoccupation with administration rather than primate fieldwork.

Nevertheless, Carpenter remained connected to primate field studies, returning to conduct a further census at Barro Colorado in 1959 and training Japanese prima-tologists in field methods in 1966 as part of the U.S.-Japan Cooperative Science Program. Carpenter also married Ruth Jones in the year of 1966, three years after the death of his first wife. Carpenter’s influence on prima-tology while at Pennsylvania State University was further extended by his involvement as an editor for Behaviour and Journal of Human Evolution and as a proposal reviewer for the National Science Foundation’s Course Development Division and Behavioral Sciences. Carpenter also provided feedback on a private basis to field researchers such as George Schaller, who went on to conduct a field study of mountain gorillas between 1959 and 1960.

Beyond field primatology, Carpenter was an influential figure in animal behavior studies conducted in a range of settings. For example, he coordinated a summer training program in Jackson Hole Wildlife Park between 1947 and 1949. These training sessions attracted professionals and students working on animal behavior studies with twenty-two individuals from eight colleges attending in 1948. Carpenter was also involved in captive studies of primates. This is seen in his 1937 article concerning captive gorillas at San Diego Zoo and in the advice he gave the Bronx Zoo about the design of their “Ape House” that opened in 1950.

During the final years of his career, Carpenter moved from Pennsylvania State University to the University of Georgia, where he assumed university duties and a position on the advisory board for the Yerkes Regional Primate Research Center, an institution focused on captive studies of primates and particularly the potential contributions of such research to biomedicine. Another enduring contribution to primate research and animal behavior studies in general was Carpenter’s compilation of the Psychological Cinema Registry, a collection containing a number of significant films of animal behavior. This venture further demonstrates the interest in technology that spanned Carpenter’s primatological and educational career.

The breadth of Carpenter’s career led to his primate research catching the attention of colleagues in psychology, anthropology, and animal behavior studies. He collaborated with many individuals in these disciplines and appears to have been well liked by some and disdained by others. Robert Yerkes and Frank Beach, assistant curator in the Department of Experimental Biology of the American Museum of Natural History in New York, became frustrated with Carpenter’s decreasing attention to field studies and by 1946 ceased to be professionally involved with his research.

For others, Carpenter’s confidence and scientific achievement were inspiring. Author Nancy Robinson, for example, presented Carpenter as a scientific role model for children in her 1973 book, Jungle Laboratory: The Story of Ray Carpenter and the Howling Monkeys. Carpenter was also an intellectual companion to playwright and author Robert Ardrey with whom he privately shared many views concerning territoriality and the relation of primate research to human society. Carpenter and Ardrey exchanged several letters and particularly discussed Ardrey’s 1966 book, Territorial Imperative.

Like his social network, Carpenter’s research interests were eclectic. This is perhaps best reflected in his fieldwork where he studied primate behavior with a panoramic lens, examining primate behaviors ranging from locomotion, territoriality, and vocalization to social and sexual behavior. Throughout his career, Carpenter passionately engaged with issues as diverse as pigeon sexual behavior, primate behavior, and technology’s role in the classroom. Such broad interests led to diverse scientific contributions but it was within the realm of fieldwork that Carpenter’s influence was most strongly felt. Both the primatological community and historians of science familiar with his work agree that Carpenter significantly shaped the development of field methods and primate research. Perhaps most importantly, Carpenter demonstrated that field studies, and particularly primate field studies, could meet scientific standards during a time in which such work was often characterized as anecdotal and inaccurate. Along with the methods Carpenter developed, this new conception of the field helped to spur the development of field primatology after World War II.


A complete bibliography and further primary sources can be found in C. Ray Carpenter’s papers at the Pennsylvania State University Library.


“The Effect of Complete and Incomplete Gonadectomy on the Behavior and Morphological Characters of the Male Pigeon.” PhD diss., Stanford University, 1931.

A Field Study of the Behavior and Social Relations of Howling Monkeys(Alouatta palliata). Comparative Psychology Monographs, vol. 10, no. 2. Baltimore, MD: Johns Hopkins University Press, 1934.

“Behavior of Red Spider Monkeys in Panama.” Journal of Mammalogy 16, no. 3 (1935): 171–180.

“An Observational Study of Two Captive Mountain Gorillas (Gorilla beringei).” Human Biology 9, no. 2 (1937): 175–196.

“Behavior and Social Relations of Free-Ranging Primates.” Scientific Monthly 48 (1939): 319–325.

A Field Study in Siam of the Behavior and Social Relations of the Gibbon (Hylobates lar). Comparative Psychology Monographs, vol. 16, no. 5. Baltimore, MD: Johns Hopkins University Press, 1940.

“Rhesus Monkeys (Macaca mulatta) for American Laboratories.” Science92, no. 2387 (1940): 284–286.

“Sexual Behavior of Free-Ranging Rhesus Monkeys (Macaca mulatta). I. Specimens, Procedures and Behavioral Characteristics of Estrus.” Journal of Comparative Psychology33, no. 1 (1942): 113–142.

“Sexual Behavior of Free-Ranging Rhesus Monkeys (Macaca mulatta). II. Periodicity of Estrus, Homosexual, Autoerotic and Non-Conformist Behavior.” Journal of Comparative Psychology33, no. 1 (1942): 143–162.

“Societies of Monkeys and Apes.” Biological Symposia 9 (1942): 177–204.

“Research and Training Activities, Summer 1947.” Annual Reports of the New York Zoological Society(1947): 53–57.

“Research and Training Activities, Summer 1948.” Annual Reports of the New York Zoological Society (1948): 40–42.

“Animal Behavior Research and Training, Summer 1949.” Annual Reports of the New York Zoological Society (1949): 46–67.

“General Plans and Methodology for Field Studies of the Naturalistic Behavior of Animals.” Annals of the New York Academy of Sciences51, no. 6 (1950): 1006–1008.

“Social Behavior of Non-human Primates.” Physiologie des Societies Animals 34, no. 3 (1950–1952): 227–246.

Naturalistic Behavior of Nonhuman Primates. University Park: Pennsylvania State University Press, 1964.

“Approaches to Studies of the Naturalistic Communicative Behavior in Nonhuman Primates.” In Approaches to Animal Communication, edited by Thomas A. Sebeok and Alexandra Ramsey. The Hague: Mouton, 1969.

“Breeding Colonies of Macaques and Gibbons on Santiago Island, Puerto Rico.” In Breeding Primates: Proceedings of the International Symposium on Breeding Non-human Primates for Laboratory Use. Berne: Generva S. Karger, 1972.


Altmann, S. “Clarence Ray Carpenter (1905–1975).” In Encyclopedia of Anthropology, edited by H. James Birx. Thousand Oaks, CA: Sage Publications, 2006.

Haraway, Donna. Primate Visions: Gender, Race, and Nature in the World of Modern Science. New York: Routledge, 1989.

———. “Signs of Dominance: From a Physiology to a Cybernetics of Primate Society, C. R. Carpenter, 1930–1970.” Studies in History of Biology 6 (1983): 129–219.

Marler, P. “Forward.” In The Cayo Santiago Macaques: History, Behavior and Biology, edited by Richard G. Rawlins and Matt J. Kessler. Albany: State University of New York Press, 1986.

Mitman, Gregg. “When Nature Is the Zoo: Vision and Power in the Art and Science of Natural History.” Osiris 11 (1996): 117–143.

Montgomery, Georgina M. “Place, Practice and Primatology: Clarence Ray Carpenter, Primate Communication and the Development of Field Methodology, 1931–1945.” Journal of the History of Biology38, no. 3 (2005): 495–533.

———. “Primates in the Real World: Place, Practice and the History of Primate Field Studies, 1924–1970.” PhD diss., University of Minnesota, Minneapolis, 2005.

Rawlins, Richard. G., and Matt J. Kessler, eds. The Cayo Santiago Macaques: History, Behavior and Biology. Albany: State University of New York Press, 1986.

Robinson, N. Jungle Laboratory: The Story of Ray Carpenter and the Howling Monkeys. New York: Hastings House Publishers, 1973.

Strum, Shirley C., and Linda Marie Fedigan, eds. Primate Encounters: Models of Science, Gender and Society. Chicago: University of Chicago Press, 2000.

Yerkes, Robert M., and Ada Yerkes. “Social Behavior in Infrahuman Primates.” In A Handbook of Social Psychology, edited by C. Murchison. Worcester, MA: Clark University Press, 1935.

Georgina M. Montgomery

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Carpenter, Clarence Ray

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