The 85th Annual Meeting of the American Association of Physical Anthropologists (2016)


Chimpanzee laterality redux

LINDA F. MARCHANT.

Department of Anthropology, Miami University

April 14, 2016 9:45, A 706/707 Add to calendar

Laterality research in wild chimpanzees (Pan troglodytes) is now in its fifth decade. How researchers characterize and interpret patterns of chimpanzee hand use (laterality) across, and within research sites, has grown accordingly. Chimpanzee manual behavior has been studied in three Pan troglodytes schweinfurthii populations – Gombe and Mahale in Tanzania and Budongo in Uganda; in three Pan troglodytes verus populations – Fongoli in Senegal, Bossou in Guinea, and Taï in Ivory Coast, and most recently, in one Pan troglodytes troglodytes population – the Goualougo Triangle, Republic of Congo. Some reports focus on single patterns, often tool-use, while others use a more exhaustive ethological approach. Over time a set of methodological and conceptual issues has emerged that bear on research design, interpretation and usefulness of results. A framework for interpreting results is provided to make a distinction between handedness, sensu strictu, the Homo condition, and handedness, sensu lato, which I will argue is more compatible with the Pan condition. Several issues that relate directly to the results obtained and their interpretation include: bouts versus events for data collection, sample sizes, combining samples within and between chimpanzee communities, what constitutes a claim of population-level laterality, degree of lateral bias, and direction of lateral bias. Finally, closer scrutiny of bimanual tasks, but most especially those that are involved in active object manipulation, may suggest more fruitful and revealing avenues of laterality research in wild chimpanzees.