Carol Berman – Rethinking the relationship between humans and non humans


Dra. Carol Berman has a Ph.D in Animal Behavior, from the Cambridge University, England, under Robert Hinde. She also has done  Post Doctoral Research at Northwestern University in the Antropology Department with Donald Sade, and Undergraduate Studies in Psychology at Brandeis University, Waltham, MA.  She is one of pioneers in the modern approaches to Animal Behavior. She is formally retired since 2017, but continues to mentor several graduate students and co-publish research articles with them at the University at Buffalo and helped to found the Graduate Program in Evolution, Ecology and Behavior. She has one co-authored edited book with Bernard Chapais, “Kinship and Behavior in Primates”, Oxford University Press, 2004, and over 80 peer-reviewed articles and book chapters. 

In her interview Carol Berman exposes a little about her work on Cayo Santiago Island – Puerto Rico.


1- Interviewer  Zélia Bora – To start, how did you become interested in primate kinship research?

Interviewe Carol Berman – I have been interested in all aspects of biology for as long as I can remember. My interest in animal behavior was sparked in middle childhood by a short book by Vance Packard called “Animal Intelligence”. It fascinated me, taught me that animal behavior was actually an area of scientific inquiry, and put me on the road to seeking a career that area. For my sixteenth birthday, I was given a subscription to “National Geographic” magazine by a friend of the family. The second issue I received had Jane Goodall’s first publication on her work with wild chimpanzees. I was captivated not only by her descriptions of chimpanzee behavior, but also by the fact that there were opportunities for people, and particularly young women, to do this kind of work. At about this age, I began to pursue summer jobs in animal behavior laboratories, and was fortunate enough to be placed in experimental/comparative psychology labs at the University of Maryland and other labs in the Washington, DC area. I learned a tremendous amount in these settings, but also realized that the approach these labs took was not what I was looking for. They used a stimulus-response paradigm with individually-housed captive animals, asking whether they could perform highly artificial tasks in an effort to reduce our understanding of complex behavior to very simple principles based purely on learning through reward and punishment. I also had nightmares about what these creatures were going through. When I went to college and majored in Psychology, I found that this approach dominated the courses and opportunities for research there too. It wasn’t until I graduated that I discovered a community of researchers interested in understanding the natural behavior of animals in their own habitats, and who did this by systematically observing animals go about their lives in the wild. Indeed I was able to find a place in a PhD program at the University of Cambridge, UK, with the same professor that advised Jane Goodall’s PhD.His name was Robert Hinde. I was thrilled and terrified at the same time.

Robert Hinde was a giant in the field of animal behavior having written ‘the bible’ that synthesized American Comparative Psychology (the approach I was already exposed to in which simple learning was deterministic) and European Classical Ethology (which was interested in natural behavior but saw it as purely genetically determined). His synthesis saw both deterministic approaches as flawed, arguing that behavior was the outcome of series of complex interactions between environmental and genetic influences;logically no behavior could be the outcome of environmental stimuli or genes alone, just as a cake is not the outcome of ingredients or the recipe alone, but rather of a complex and variable  interaction of the two. At the time, he was focusing his research on understanding mother-infant relationships in small captive social groups of rhesus monkeys as a way to develop a science of social relationships and to test John Bowlby’s attachment theory of social bonding. With his guidance, I designed a study of free-ranging rhesus monkeys on Cayo Santiago, Puerto Rico, to test whether some of his findings could be verified in a larger, naturally formed, and species-typically organized social group of the same species. My aim was also to expand our understanding in this more natural setting to include a description of the ways in which infants become fully integrated members of their societies. In so doing, I found that among other factors, maternal kinship relationships were key, and kinship became a focus of my research throughout my career. Mothers introduce their infants to their close maternal kin from the beginning. They carry their infants with them as they continue to interact in a friendly way with a subset of group members who tend to be their own close kin. Mothers also are more tolerant of these individuals when they attempt to handle or interact in other ways with their infants. Through maternal transmission, they come to not only associate with close kin more than others, they also favor them in all kinds of friendly and cooperative interaction and support them in conflicts with other families that are less closely related.

Z.  And how did this research affect your personal views on human and non-human relationship?

C.  I had always leaned toward viewing humans as biological beings (rather than beings separate from other animals and ‘one step below the angels’) and as kindred to other animals, particularly those species to which we are closely related. Finding how much primate societies were shaped by kinship relationships reinforced this view, and made me appreciate the power of kinship in human societies even more. More generally, it made me appreciate the importance of social bonds and the ways that both humans and nonhumans benefit from them, acquire them, maintain, nurture and use them in ways that may benefit or harm others.


Carol Berman grad students on Cayo 

Dunayer, katharine Burke and Krishna Balasubramanian


2- Z.  How does the research on Cayo Santiago benefit the studies on the environment and especially the lives of the primates?

C.  Research on Cayo Santiago has facilitated our ability to understand primate societies, not just of rhesus monkeys, but of all primate species. Cayo Santiago is an island population that allows researchers to keep track of individuals throughout their lives and over generations more easily than in most field sites. In addition, because our records are so complete, and because the monkey groups are relatively large and unmanipulated, yet naturally formed and species-typical in organization, we have been able to discern certain organizing principles of their societies, such as kinship and dominance, more easily and more clearly than in most field sites. This has facilitated the abilities of other researchers to see these same principles at work in smaller wild groups of many species. This knowledge in turn has informed managers of wildlife as well as of captive primates about the social and environmental needs of primates that they may otherwise have ignored. For example, rhesus monkeys in India live alongside humans and can cause a great deal of damage to homes and crops. Efforts to remove them from areas where conflict is great began with haphazard trappings of random monkeys without regard to the social structure of the groups they were disturbing. This often caused the groups to split and multiply, causing additional conflict with local people. Using a knowledge of the social bonds that contributed to group structure, a colleague of mine, Dr. Iqbal Malik, designed an inexpensive procedure to humanely trap whole groups and to re-locate them to suitable habitats where the local people welcomed them. In a captive example, an understanding of social structure, and specifically the fact that female rhesus monkeys remain in the groups into which they were born for life, has led to the reduction of aggression among females who must be removed from their groups periodically and then returned. At one time, they were not necessarily returned to the same group from which they were taken, provoking severe aggression against them. Simply understanding that females form the permanent core of their groups and are hostile to females in other groups prevents harm to them in this situation.


Island of Cayo Santiago 


Cayo Santiago is not truly wild; although the monkeys roam freely on a lush (until Hurricane Maria) island, and although manipulation is limited to a short annual period when noninvasive tests and measurements are allowed, the monkeys have no predators, and they are supplied with ample amounts of food and clean water. Nevertheless, research there can help to interpret the importance of some environment factors in truly wild populations. This is partly because many environmental factors are relatively constant on Cayo Santiago: through the year, daylength and temperatures vary within only a narrow range, and water and amounts of food provided per monkeys are consistent and are distributed over the island in the same manner. Thus, when we see the monkeys’ behavior vary from group to group, over time or between individuals, we are likely to attribute these variations to social factors such as group size or composition rather than environmental variation. If other researchers who study this species or related species in the wild see similar variations in behavior, they will have a basis for hypothesizing that these variations are also due to social factors rather than simply assuming that they are due to any environmental variation they see. So research on Cayo Santiago can indirectly guide research on the effects of the physical environment vs. the social environment. The constancy of the environment on Cayo Santiago can also aid in understanding the importance of particular environmental features on Cayo Santiago. For example, rhesus monkeys are not normally territorial. Rather, different social groups occupy overlapping home ranges, essentially time sharing the same piece of real estate. However, one group on Cayo Santiago displayed territorial behavior when it occupied a small part of the island that connected with the rest of the island via a narrow isthmus. The group lined up at the entrance to its area and drove off other groups attempting to enter. This demonstrated that environmental features that allow easy defense of an area and its resources can alter the behavior of normally non territorial animals, bolstering evidence for an ecological principle about the relationship between defensibility and territoriality across species. 


Rhesus pair grooming


3- Z.  How do concepts of kin preferences based on matrilineal dominance system possibly exemplify human’s history from matriarchal clan to patriarchal family? (we have here in mind references to the classical thesis defended by Evelyn Reed on her book Woman’s evolution). 

C. I hesitate to tackle this question because I do not consider myself an expert on human history. My understanding of the evolution of human behavior generally ends before the appearance of human beings with fully human language andsymbolic abilities. Rather I have paid more attention to ideas surrounding the transition from nonhuman primate behavior and societies to possible early hominine forms. Having said that, it is my understanding that Reed’s ideas have struck a note with feminist and Marxist intellectuals, but not with biological anthropologists who have taken a very different approach. Apparently, Reed based her ideas on early observations of contemporary human cultures that lived primarily through hunting and gathering or simple agriculture. At the time that she wrote, little information was available on nonhuman primate societies, so she was unable to take these societies into consideration when contemplating human origins and history. Current biological anthropologists are able to consider the evolutionary origins of human society, while also taking into consideration general principles of behavior and ecology that apply to a wide range of species. Thus when they study contemporary societies that have simple technologies and economies, they often ask to what extent human societies conform to these more general principles?Conversely, to what extent do our unique human attributes make us special cases? An excellent example of this approach is the current hypothesis of Sarah Hrdy and others that many special attributes of humans evolved as a result of our becoming a cooperatively breeding species, similar in some key ways to cooperatively breeding marmosets and tamarins as well as other nonprimate species. In cooperative breeding, success rests on the willingness of group members, especially kin, to help and support mothers and their dependent offspring. Such supplementation allows human mothers to reproduce more quickly than our close great ape relativeswhose mothers care for infants on their own. Supplementation has also been hypothesized to drive evolutionary increases in social perceptiveness, intelligence,mutual understanding, and cooperation, including coordinated group action.Under this perspective, the strong bonds between rhesus mothers and their offspring, and the matrilineal (not matriarchal) structure of their societies can be seen as a prerequisite to the evolution of cooperatively breeding, even though kin favoritism in this species does not include supplementing mothers per se.

Strong mother-offspring bonds and matrilineal social structures also form a necessary building block for another current hypothesis about the origins of human societies. While acknowledging the vast amount of diversity in human societies, Bernard Chapais focused on common attributes of human social structure and broke them down into several component parts.Some he noted were unique to humans whereas others could be found in other primate species. However, no other species displayed the full complement of these components. He then used the logic of phylogenetic reconstruction, commonly used by evolutionary ecologists, to trace the separate evolutionary origins of each component and their stepwise reconfiguration to a uniquely human form. In this scenario, one of the earliest building components were the strong mother-offspring bonds and matrilineal social structures typical of rhesus monkeys (and other macaques and baboons).

Both these models are notable because they go beyond earlier models that focused on the social structure of a particular nonhuman primate and attempted to go directly from that social structure to human attributes and societies. Chimpanzees were often chosen for their close phylogenetic relationship to humans, or matrilineally structured groups were chosen as ‘typical nonhuman primates’. However, as we learned more about a variety of primate species, it became clear that they display very diverse social structures, and that there is no typical one. We also learned that bonobos, which are equally closely related to humans as chimpanzees, differ from them in behavior and social structure in important ways. Thus, the single species approach could no longer be justified. Hrdy’s and Chapais’ approaches gather strength by taking into consideration a much larger body of evidence from primates that show both similarities and differences to humans, and that apply general principles derived from analyzing the sources of this variation.

For a fascinating view of the possible evolutionary and environmental underpinnings of human patriarchy from the point of view of primatology, I recommend Barbara Smuts’ “The Evolutionary Origins of Patriarchy” (reference below). Like Hrdy and Chapais, this model makes use of both similarities and differences in the position of females among nonhuman primate species to construct plausible and testable hypotheses about the conditions that are likely and unlikely to lead to patriarchy in human societies. The separation of women from their kin at marriage is one that is particularly striking to me.


Delivering the baby to mon


4- Z. What else can we learn about primates in terms of love and altruism. Can you tell us more based on the inferences we can make from your article “Primate kinship: contributions form Cayo Santiago”?

C. I hesitate to use the term ‘love’ because it has so many meanings and generally refers to an emotion that we can only infer in others rather than a behavior that we can observe. In contrast, altruism, as it is used by animal behavior researchers refers to behavior that benefits the receiver of the behavior at some cost to the giver. Cooperation similarly refers to behavior that benefits the receiver and may or may not benefit the giver as well.

Cayo Santiago researchers and their alumni have done important research on the topic of altruism, and more generally cooperation, among animals, beginning with the findings of strong kin preferences among maternally-related rhesus monkeys. Early studies assumed that this was an example of altruism and an evolutionary outcome of kin selection. Over the years, researchers have tested this idea increasingly rigorously, and have found strong evidence that kin selection can indeed account for some observed examples of altruism favoring kin among monkeys, although it may be limited to only very close relatives. The evolutionary processes that shape other potential examples of altruism and cooperation, including the giving and receiving of grooming, are still to be worked out. One of my current PhD students, Erica Dunayer, is currently examining which hypothesized principles best fit the patterns of grooming we observe on Cayo Santiago:  kin preferences, tit for tat reciprocity regardless of kin relatedness, the strength of long term social bonds regardless of kin relatedness, or current ‘market’ conditions. The idea that there is a rudimentary biological ‘market economy’ in grooming is the most recent hypothesis that likens grooming to a form of currency that can be exchanged for grooming itself or for other services, including tolerance by dominant individuals at shareable resources and support in conflicts with opponents. It addresses cooperation, but not as a form of altruism, and certainly not ‘love’. So it will be exciting to see whether it prevails or not over the more relational hypotheses. When grooming is exchanged for other services or desirable opportunities, the biological markets hypothesis predicts that supply and demand principles will operate, such that more grooming is required to ‘purchase’ rare opportunities or services than readily available ones. As such, Erica isalso examining exchanges of grooming of mothers before the mothers allow their infants to be handled by eager infant admirers. Must they groom the mother longer when few infants are available in the group than when many are available? She has just completed her data collection on Cayo Santiago, so we eagerly await the results of her study, which promises to be the most comprehensive of its kind, in the next year.

5- C. Final remarks.

I’ll end by recommending further reading of the authors I have cited above.

Bernard Chapais (2008). Primeval Kinship: How Pair-Bonding Gave Birth to Human Society, Harvard University Press, Cambridge, MA.

Sarah Hrdy (2009). Mothers and Others: The Evolutionary Origins of Mutual Understanding. Harvard University Press, Cambridge, MA.

Ronald Noë, &PeterHammerstein (1995). “Biological Markets”. Trends in Ecology & Evolution, 10,336-339.

Barbara Smuts (1995). “The Evolutionary Origins of Patriarchy”. Human Nature 6(1): 1-32.


OCTOBER, 19th 2018. 


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