In the spring of 2013 Elizabeth Tinsley Johnson, PhD candidate from the University of Michigan, was awarded a Leakey Foundation research grant for her project entitled “A test of the vocal grooming hypothesis in the gelada.”
Geladas (close relatives of baboons) are exceptionally unique primates that are only found in the highlands of Ethiopia. What makes them unique? First, they are the only primates in the world that eat primarily grass, which means they spend a lot of time foraging – which sometimes comes at the expense of socializing. Maintaining social bonds is a critical part of gelada life, because they live in large, complex social groups. For females, in particular, the ability to maintain ties with other females in their unit is crucial for maintaining unit cohesion. Geladas are also unique in that they are exceptionally vocal primates, leading some researchers to speculate that the function of their constant chatter is to make up for lost grooming time. If true, the so-called ‘Vocal Grooming Hypothesis’ (e.g., Dunbar 1996) carries implications for how, and why, human language evolved.
For the last year (Oct. 2013-Oct. 2014), graduate student Elizabeth Tinsley Johnson has been studying geladas in the Simien Mountains National Park, Ethiopia. Her research aims to understand how female geladas maintain social bonds and the potential benefits these relationships carry. In particular, Tinsley Johnson is interested in the potential role that vocal contact plays in navigating social relationships. To this end, she has collected climatological, demographic, behavioral, and hormonal data on ~45 adult females across 12 social units. Now back at the University of Michigan, Tinsley Johnson will spend the next year analyzing her data and presenting her results to professional conferences and in journal publications.