The Evolutionary Past and the Research Future: Environmental Variation and Life History Flexibility in a Primate Lineage

Abstract

The chapters in this volume demonstrate that baboons (genus Papio) are a diverse and flexible group that occupies a wide range of habitats. Further, the habitats occupied by baboons are characterized by frequent short-term environmental change (particularly seasonal change) and, for at least some populations, striking long-term change as well. Some of the environmental change is relatively predictable but some is highly unpredictable. What is the relationship between the diversity we observe in baboon life history and behavior and the variability the baboons experience in their physical and social environments? We explore answers to this question in the context of a recent hypothesis for hominid evolution proposed by Potts (1996, 1998a,b), the variability selection hypothesis. This hypothesis proposes that the constantly changing environments that typified the East African paleoenvironment resulted in selection for flexible, generalist organisms (such as humans and baboons) that possess the ability to take advantage of the new ecological opportunities that emerged with habitat change. We propose that baboons are a particularly good lineage in which to explore the consequences of variability selection—selection in response to changing environments. We provide examples of baboons’ adaptability, particularly in the context of environmental variability and change, and we suggest directions for future research that take advantage of the remarkable opportunity for comparative work in this species, given the relatively large number of baboon field studies. We emphasize that understanding the response of baboons to environmental variability and change is potentially important both because of the light it can shed on the role of changing environments in selecting for flexible species like baboons and humans, and because environmental change will increasingly characterize the global environment in which wild primates—most of them less flexible than baboons—will need to persist.