KCP at the AAPAs 2013

The Kanyawara chimpanzees are going to be featured in many of the talks and posters at the 82nd annual meetings of the American Association of Physical Anthropologists in Knoxville, TN. If you’re going to be at the meetings, come on by and check out all of the latest research happening at the Kibale Chimpanzee Project!

WEDNESDAY, April 10th

Undergraduate poster session

6:00 to 8:00 pm

Energetics of infant chimpanzees: Implications of nursing and feeding behavior by Joel Bray et al.

Growing up chimpanzee: A study of body size and growth patterns in Pan troglodytes by Nicholas Brazeau et al. 

THURSDAY, April 11th

Session 11. Primatology Posters: Sex, Sociality, Ontogeny, Captivity

All day: The interplay between behavior and disease: Investigating pathogen transmission dynamics in wild chimpanzees with social network models by Julie Rushmore et al.

Session 15. Primatology: Sex, Aggression and Competition:

1:00 pm: The development of aggressive play behavior in wild chimpanzees by Zarin Machanda et al.

1:30 pm: Effect of opponent distance on post-conflict behavior in wild chimpanzees, Kanyawara, Kibale National Park, Uganda by Jess Hartel and Craig Stanford

2:30 pm: Intergroup aggrssion and within-group cohesion in wild chimpanzees by Martin Muller et al.

3:15 pm: Context of Copulation Calls in Wild Chimpanzees by Melissa Emery Thompson et al.

FRIDAY, April 12th

Session 21. Invited Symposium: The High Price of Success: Costs of Reproductive Effort in Male Primates and Humans

8:00 AM to 11:30 AM

Organized by KCPers Alexander Georgiev and Melissa Emery Thompson, Discussant: Richard Wrangham

9:45 am: Physiological costs of dominance and mating effort in male chimpanzees by Alexander Georgiev et al.

Session 38. Nonhuman Primates in Human-Modified Habitats: Explorations in Ethnoprimatology

Afternoon: How Mentawai Island primate characteristics affect hunters’ prey choice by Lisa Paciulli and Kristin Sabbi

SATURDAY, April 13th

Session 42. Paleoanthropology: Later Homo

8:30 am: Honey exploitation by chimpanzees and hunter-gatherers indicates an ancient use of fire by humans by Richard Wrangham and Zarin Machanda

Session 51. Primatology: Ecology, Behavior and Flexibility

2:45 pm: A cross community comparison of female chimpanzee (Pan troglodytes schweinfurthii) social behavior in Kibale National Park, Uganda by Monica Wakefield and Kyleb Wild

You can download the whole program with abstracts here. See you in Tennessee!

 

New study on teething in chimpanzees

The Kanyawara chimpanzees are the focus of a recently published study in the Proceedings of the National Academy of Sciences examining patterns of tooth development. Researchers from the Kibale Chimpanzee Project partnered with Harvard Professor Tanya Smith to determine the age at which infant chimpanzees in our community erupt their first molar teeth. Our two wildlife photographers, Ronan Donovan and Andrew Bernard, spent two years in the field photographing infant chimpanzees in situations when their mouths would be open enough to see if their back teeth had come in. I’m not sure about Ronan and Andrew, but I can certainly think of worse ways to spend time than photographing baby chimpanzees playing with each other!

Ronan Donavan photographing the Kanyawara chimpanzees. Photo by Alex Georgiev.

We obtained thousands of photographs and were able to determine that our infants erupted their first molar teeth before the age of 3.3. years. Interestingly, when we compared this pattern to our long-term behavioral data we found that infants continued to nurse long after these teeth came in. This was surprising since primate-wide patterns indicate that molar tooth emergence is related to the period of weaning. Instead, we found that molars come in around the time that infants begin showing adult-like patterns in solid food consumption. This is the first study of a wild population of primates that has both the dental and corresponding long-term behavioral data which means we can really test the relationship between tooth emergence and feeding/nursing behavior for each individual.

Azania, one of our female infants, showing that both of her lower first molars (M1s) have erupted before this photo was taken at age 3.1 years. Photo by Andrew Bernard.

Understanding the timing of these developmental milestones in wild chimpanzees is particularly important because evolutionary anthropologists have been debating for years whether early humans followed ape-like or human-like patterns of growth. Since chimpanzees are our closest living relative, it is important to make sure that we document their development before we can fully interpret the fossil evidence. Prior to this study, almost all the research on dental development in chimpanzees came from captive individuals or from a small sample of skeletons collected in the wild and it is unclear how representative these data are of living wild animals. By using this novel photographic approach, our study shows that molar eruption in our chimpanzees is not delayed relative to captive animals and both are very similar to data gathered from fossils of early human ancestors.

For more information about this study and to see more photos and videos of our infants showing off their teeth, please check out our detailed press release here: http://www.heb.fas.harvard.edu/Press3/

Student Research at Kanyawara

Alex (right) is holding the laser apparatus while Nick (left) is snapping the photo.

This summer, the Kibale Chimpanzee Project welcomed a number of student researchers, including Nick Brazeau and Alex Smith from Harvard University. Nick, a rising senior, is working on his senior thesis project by collecting body size estimates of the Kanyawara chimpanzees. Alex, a rising junior, is his tireless research assistant. It is difficult to measure body sizes of wild chimpanzees, because researchers can’t easily convince them to climb onto scales. Instead we employ non-invasive methods like photogrammetry. Nick has assembled an apparatus that contains two laser beams mounted in parallel at a set distance of 5 cm. The laser apparatus is attached to a camera, and the projected beams provide a size reference in the photograph.

The lasers show up as green dots on the chimps bodies and are exactly 5cm apart. This method allows us to get estimates of body length like the one here of Big Brown.

For each chimpanzee, Nick and Alex measure multiple body parts, including the forelimbs, hindlimbs, trunk, back, skull, and testes. These measurements will be compared to body size estimates of chimpanzees using multiple methods, including a comparison with captive chimpanzees of known weights. Such data will be valuable in answering questions about growth, life history, the relationship between body size and dominance, and the costs of locomotion.