Guest post by Alexander Weiss of the University of Edinburgh, United Kingdom

Early on in her behavioural observations of the chimpanzees at what is now known as Gombe National Park, Jane Goodall was struck by their personalities, which were as distinct as our own¹. However, upon sharing her observations with a ‘respected ethologist’, she was told that, yes, animals differed in their behaviour, but that this was best ‘swept under the carpet’ (pp 11-12)².

Goodall, thankfully, felt differently and in 1973 Peter Buirski, then an Assistant Professor in the Department of Psychology at John Jay College of Criminal Justice, and a student in the Psychoanalytic Institute of Postgraduate Center for Mental Health, travelled to Gombe. While there he asked seven students and post-doctoral researchers to use the ‘Emotions Profile Index’ to describe the personalities of 24 chimpanzees³. These descriptions were used to assign scores on eight dispositions – Trustful, Distrustful, Controlled, Dyscontrolled, Aggressive, Timid, Depressed and Gregarious – to each chimpanzee. Ratings of the same chimpanzees by two or more researchers were similar. The ratings also showed differences in dispositions between the sexes; some of which resembled observed gender differences in humans⁴ (e.g. female chimpanzees were more Trustful than males), and others that did not (e.g. male chimpanzees were more Gregarious than females). In addition, personality in males was associated with their position in the social hierarchy⁴. Finally, these data predicted a series of dramatic events; Passion (a chimpanzee with a ‘deviant’ profile) together with her daughter, kidnapped and ate the infants of other chimpanzees⁵.

My interest in chimpanzee personality began after I started my PhD in Psychology at the University of Arizona. Having initially planned to study moth learning, Jim King introduced me to personality research by inviting me to work on data on captive chimpanzee personality that he had collected. He ended up becoming my PhD supervisor and a long-time collaborator. Since then, I have investigated personality in captive chimpanzees and other non-human primates as well as studying personality, health and ageing in humans, the latter of which I started during my post-doctoral training under Paul Costa at the National Institute on Aging.

Shortly after my post-doc and after starting my current position at Edinburgh, I spoke to Anne Pusey and Mike Wilson about collecting chimpanzee personality data at Gombe. Both were enthusiastic and encouraging, and in 2009 I obtained enough funding to make it possible. Things then moved quickly. Mike and Anne translated the Hominoid Personality Questionnaire, which I developed with Jim King, into Swahili. They also identified who among the Tanzanian field assistants would rate which chimpanzees. We included deceased individuals as these included famous chimpanzees, such as Flo, which were familiar to the older field assistants.

My first visit to Tanzania took place in 2010 from late September to early November. I spent most of that time at the Gombe Stream Research Centre in Kigoma, and gathered data on the chimpanzees of the Kasekela community. Anthony Collins (the scientific director), Shadrack Kamenya and Deus Mjungu contacted and arranged visits from the field assistants. Bernadetha Tungu, my capable translator, assisted with the data collection. The sheer height of the stack of questionnaires that each field assistant was asked to complete would intimidate many people, but they took the task seriously and diligently worked through the paperwork. I then travelled to Gombe National Park where I watched the field assistants follow and record the behaviours of individuals. It was also the first time that I saw chimpanzees in the wild. Highlights included an impressive, fearless high-ranking male, playful juveniles and a chimpanzee in a patch of sunlight, with a beatific look on his or her face.

My second trip to Tanzania took place over two weeks in the late summer of 2011 and I was joined by my new wife, Emily. We spent nearly the whole time in Gombe. Again, Anthony, Shadrack, Deus, and Bernadetha provided crucial support, and the field assistants came through, this time rating members of the smaller Mitumba community. At the end of both trips, I had a staggering amount of data on perhaps the most famous wild chimpanzees in the world.

In their papers, Buirski and his colleagues provided personality scores for the chimpanzees^3,5. It was therefore possible to test how well the ratings I collected lined up with those collected in 1973. The answer turned out to be ‘surprisingly well’, especially considering the use of different questionnaires by different people, who would have had distinct experiences with the chimpanzees. However, there were also surprises, such as the lack of correspondence between a few pairs of similar personality scales.

I enjoy sharing my memories of Gombe, the chimpanzees, and the field assistants, and I wanted to share these data too, so that others can study wild chimpanzee personality and its attendant fitness consequences. I was thus delighted to receive a Sabbatical Scholarship from the National Evolutionary Synthesis Center in 2014, which enabled me to work closely with Anne Pusey, Steffen Foerster, and others to make these data available and thereby share the field assistants’ knowledge with the wider scientific community. Our personality data, along with our comparisons to the 1973 ratings, were published today in Scientific Data⁶.

The study of animal personality no longer has the pariah status it once “enjoyed”. However, less work has focused on large, long-lived mammals in the wild. By making these data freely available and accessible, I hope to make studying one such species possible for current researchers and for future generations too.

References

1. van Lawick-Goodall, J. In the shadow of man. (Houghton Mifflin, 1971).
2. Goodall, J. Through a window: 30 years of observing the Gombe chimpanzees. (Weidenfeld & Nicolson, 1990).
3. Buirski, P., Plutchik, R. & Kellerman, H. Sex differences, dominance, and personality in the chimpanzee. Anim. Behav. 26, 123-129 (1978).
4. Costa, P. T., Jr., Terracciano, A. & McCrae, R. R. Gender differences in personality traits across cultures: Robust and surprising findings. J. Pers. Soc. Psychol. 81, 322-331 (2001).
5. Buirski, P. & Plutchik, R. Measurement of deviant behavior in a Gombe chimpanzee: Relation to later behavior. Primates 32, 207-211 (1991).
6. Weiss, A. et al. Personality in the chimpanzees of Gombe National Park. Sci. Data 4, 170146 (2017).