Grass-eating monkeys in the genus Theropithecus were widespread in Africa and beyond in the Plio-Pleistocene. Roughly 500,000 years ago, most species of grass-eating monkeys disappeared, leaving only the gelada monkey (T. gelada) that today is endemic to the Ethiopian highlands. The ecological drivers of the rise and fall of this unique primate genus remain a topic of enduring interest in biological anthropology. Theropiths have also served as important referential models for understanding human evolution. In this talk I review the biology and ecology of Theropithecus and suggest a unifying framework for understanding its distinctive dental, post-cranial, and behavioural adaptations for eating grass. I propose the utility of modern geladas for informing the behaviour of fossil theropiths. Integrative data on foraging behaviour are presented from long-term research conducted at Guassa, Ethiopia. I conclude with perspectives on how gelada research can help us to better understand how hominins coped in savanna habitats during the Plio-Pleistocene.

Dr Vivek Venkataraman is a biological anthropologist based at the University of Calgary, Canada. His research specializes in the evolution of human and nonhuman primate foraging strategies.