Specialized chimpanzee technology in Northern DR Congo

Dr Cleve Hicks, Max Planck Institute for Evolutionary Anthropology Leipzig, Germany / Artes Liberales UW, Poland

Date: Wednesday, the 13th of June 2018 at 1PM, Cent Lecture Theatre 0142

I describe a new set of tool use, nesting and food-pounding behaviors in the Bili-Uéré population of Eastern chimpanzees (Pan troglodytes schweinfurthii) spread across an area of at least 50,000 km² area in northern DRC. These chimpanzee use long probes used to harvest epigaeic driver ants (Dorylus spp.), wands to dip for Dorylus kohli, short probes used to extract ponerine ants and the arboreal nests of stingless bees and stout digging sticks to acquire honey from underground meliponine bee nests. Epigaeic Dorylus tools were significantly longer than the other tool-types and Dorylus kohli tools were significantly thinner. Tools classified as terrestrial honey tools were a significant predictor for brushed and blunted tools ends, consistent with their presumed use. We also describe two potential new tool-types, an ‘ant scoop’ and a ‘fruit hammer’. The Bili-Uéré chimpanzees were also documented to pound open Cubitermes sp. and Thoracotermes macrothorax termite mounds, while ignoring the abundant Macrotermes muelleri mounds which are preyed upon using tools by chimpanzees in other populations. Our results demonstrate multiple behaviors shared across a large, ecologically-diverse region but with subtle differences in prey choice and techniques, which may be explained by a recent chimpanzee expansion across the region and population interconnectedness.