Group living confers a variety of benefits to individuals within the group, including predator detection, defense and high rates of food acquisition. Animals that form groups with close genetic relatives may also benefit from opportunities to help kin at minimal cost, thus increasing the helper's indirect fitness. Individuals in kin groups also gain direct fitness advantages through decreased within group aggression, lowered risk of infanticide, and coalitionary support. However, much of what we know about the effects of kinship comes from relatively simple, single level social systems. We know very little about how kinship works in complex, multi-level societies like those found in modern humans. Moreover, until recently only long-term studies have had the pedigree data to map maternal relatives. Now, genetic techniques that combine non-invasive sampling with PCR-based genotyping allow researchers to evaluate the interaction between relatedness and social systems in species where relationship data are lacking. This project applies these new genetic techniques and detailed behavioral observation to the unusual, highly complex social system of gelada monkeys (Theropithecus gelada). Geladas live in large, multi-level social systems resembling those of many human hunter-gatherer societies. Gelada social structure appears to be considerably more complex than that of their close phylogenetic relatives, the well-studied baboons. Therefore this research provides important new data on kinship-behavior interactions and the evolution of complex societies in mammals.
This project, in collaboration with the University of Michigan Gelada Research Project (UMGRP), offers both genetic and behavioral information on geladas, which are listed as "rare" by the World Conservation Union. The project employs Ethiopian scientists and rangers, and established both multi-intuitional and interdisciplinary collaborations. The co-PI participates in community outreach lectures to Ethiopian guides, tourists, and local K-12 students, as well as giving presentations to elementary school students in the Northeast U.S.
Broadly, my research focused on the evolution of sociality and social behavior. However, to understand the evolution of social behavior, we must first gain a comprehensive understanding of the social systems in which those behaviors occur. Therefore, for my PhD, I studied the evolution of one of the largest, most complex, and most variable social systems of the non-human primates. I used a combination of non-invasive genetic analyses and detailed behavioral sampling, to understand the unusual, highly complex social system of gelada monkeys (Theropithecus gelada). Geladas live in large, multi-level social systems resembling that appears to be considerably more complex than that of their close phylogenetic relatives, the well-studied baboons. Overall my research, in collaboration with other research done by the University of Michigan Gelada Research Project, has provided important new data on kinship-behavior interactions and the evolution of complex societies in mammals. Using a combination of behavioral, ecological and genetic data, I was able to gain a better understanding of the effects of cooperation and social bonds on fitness. Specifically, my work resulted in the most comprehensive description to date of how and under what conditions small, nuclear reproductive groups of geladas fission and fuse with one another to produce the hierarchical levels of gelada society [Snyder-Mackler et al, 2012, Int. J. of Primatology]. I then worked to uncover the effects of kinship and population genetic structure on individual behavior in geladas. I found that unrelated males who cooperate with each other have higher reproductive success and experience fewer stressful events than males who do not cooperate with other males [Snyder-Mackler et al., in revision, Proceedings of the Royal Society B: Biological Sciences]. Further, I found that the female-female relatedness structure was highly correlated with their tiered association patterns. Female-female bonds are therefore maintained across the different levels of society and, as such, are fundamental to maintaining its multiple levels. Together, my findings have highlighted the adaptive importance of forming strong social bonds with kin (in females) and non-kin (in males). They also provide important comparative and evolutionary insight into the origins of sociality and the evolution of cooperation amongst both kin and non-kin. BROADER IMPACTS: The behavioral and genetic focuses of my research has implications for conservation, because it involves both field monitoring (demography, population biology) and measuring the genetic diversity of the gelada, which are listed as "rare" by the World Conservation Union (IUCN). Additionally the research site in Ethiopia, the Simien Mountains National Park, is on the list of World Heritage in Danger and faces severe encroachment from humans. With regards to local community outreach and education, this past year I established connections with teachers at three different local schools (Cedar Grove Elementary, Toms River, NJ; Paul V. Fly Elementary, Norristown, PA; & Thomas Fitzwater Elementary, Upper Dublin, PA) where I gave presentations to K-12 classes promoting science and conservation. In doing work in a third-world country I also had the wonderful experience to learn Amharic, the local language, and to interact with the local villagers and park rangers in the area. This experience provided me with an opportunity to connect broader outreach efforts with my research, via both bi-monthly talks to the local community about the research I was conducting and as a featured blogger for the New York Times (I chronicled my field work for two months in the fall of 2010 through the NYT "Scientist At Work" series: http://scientistatwork.blogs.nytimes.com/author/noah-snyder-mackler/). Both of these interactive forums taught me the importance of clearly communicating your research to the general public, which has been essential to my development as a researcher.
