Picky Primates: Chimps play favourites when picking tools for ant dipping
The new research, published today in the American Journal of Primatology, was led by Dr Kathelijne Koops from the University of Cambridge’s Division of Biological Anthropology and Junior Research Fellow of Homerton College.
"Ant dipping is a remarkable feat of problem-solving on the part of chimpanzees," said Koops. "If they tried to gather ants from the ground with their hands, they would end up horribly bitten with very little to show for it. But by using a tool set, preying on these social insects may prove as nutritionally lucrative as hunting a small mammal — a solid chunk of protein."
Koops points out that if Alchornea hirtella is nowhere to be found, chimps will fashion tools from other plants — but seemingly only after an exhaustive search for their preferred tool provider.
Previous research has shown that chimpanzees will actually select longer tools for faster, more aggressive types of army ants. The average ‘dipping’ tool length across the study was 64 centimetres, but dipping tools got up to 76 cm.
The question for Koops is one of animal culture: how do chimpanzees acquire knowledge of such sophisticated techniques?
"Scientists have been working on ruling out simple environmental and genetic explanations for group differences in behaviours, such as tool use, and the evidence is pointing strongly towards it being cultural," said Koops. "They probably learn tool use behaviours from their mother and others in the group when they are young…"
"This study is part of a big ongoing research project. The next stages will involve looking at social opportunities to learn: how much time do youngsters spend within arm’s length of other individuals; how much time do they spend close to their mother; as well as innate predispositions to explore and engage with objects,” said Koops. (continue reading)
Kathelijne Koops, Caspar Schöning, William C. McGrew, Tetsuro Matsuzawa.Chimpanzees prey on army ants at Seringbara, Nimba Mountains, Guinea: Predation patterns and tool use characteristics. American Journal of Primatology, 2014; DOI: 10.1002/ajp.22347
Check out the videos of chimp tool use included with the University of Cambridge press release!