Natural selection has given rise to societies, altruism, empathy and kindness. Why and how did this happen? The origin and stability of cooperation is a classic topic in evolutionary biology. For my Ph.D. dissertation, I'm studying cooperative food sharing in vampire bats. Members of these highly social and cooperative species regurgitate food for both related and unrelated roostmates who failed to feed. Without some kind of social enforcement, such a system could invoke an evolutionary "tragedy of the commons" where food donors are ultimately outbred by freeloaders that receive the reproductive benefits of sharing yet never share with others. But somehow the bats avoid this. Do food sharing bats actively prevent cheating?

Jerry Wilkinson's original study of vampire bat food sharing is the classic textbook example of reciprocity-- the idea that food donations are a costly social investment that ensures future food sharing. Individuals can enforce cooperation by rewarding their previous donors and withholding aid to potential freeloaders. However, this interpretation of food sharing is highly controversial and many important questions remain. Is food sharing between unrelated bats a byproduct of kin selection? Are unrelated bats sharing their food simply to avoid harassment by hungry bats? Is previous social experience a better predictor of food sharing than genetic relatedness? What social information do vampire bats use when deciding whether to help others? Will the bats punish freeloaders by reducing aid to partners who don't reciprocate? Do the bats compete to be good social partners? I hope to answer these questions through controlled observation and experiment. 

Read Wilkinson's original 1984 paper in Nature. See also this past coverage in David Attenborough's Trials of Life (video), Scientific American magazine, The Selfish Gene, Perspectives on Animal Behavior, and Radiolab (audio). 

I'm currently supported by the Ford Foundation as a Ford Predoctoral Fellow. Past work on this project has been graciously supported by the University of Maryland, Cosmos Club Foundation, American Society of Mammalogists, Explorer's Club Washington Group, and Sigma Xi. I'm currently working in collaboration with the Organization for Bat Conservation.