This is an extract from Our Human Story, our newsletter about the revolution in archaeology. . Chimpanzees, along with bonobos, are our closest living relatives. Of all the millions of other animals on Earth, they are the ones that are most like us.
And the more we learn about chimpanzee behaviour, the more obvious the similarities become. For instance, wild chimpanzees peer at each other: one chimpanzee will sit close to another and closely watch what they’re doing. Nora Slania at the Max Planck Institute of Animal Behavior in Germany and her colleagues found that, from a young age, chimps peer at others as they perform a range of tasks.
This included complex tasks like making tools, but also supposedly simple things like feeding and grooming. The implication is that a great deal of chimpanzee behaviour is culturally learned by watching others. Obviously, chimps will instinctively try to eat food, but it’s not obvious what is good to eat, or how to peel a fruit or crack a nut.
One way to learn is by watching how the adults do it. Some chimpanzees have figured out how to eat army ants, which form huge colonies comprising millions of individuals. When the ants need to eat, they assemble into marching columns guarded by soldier ants with powerful jaws.
While there is obviously plenty of nutrition in an army ant colony, one must be careful when dealing with them. In Senegal, chimps catch Dorylus army ants living on the savannahs. Andreu Sánchez-Megías at the University of Barcelona in Spain and his colleagues argue that chimps vary their strategies depending on how aggressive the ants are.
Army ants that hunt in leaf litter are not very aggressive, so chimps sometimes forage for them by hand. In contrast, army ants that hunt on the surface of the ground are aggressive, so the chimps catch them by lowering a stick, which the ants bite onto – allowing the chimp to eat them in relative safety. What’s more, the chimps prefer to catch these species while standing upright, or on a raised platform, like a bent tree branch.
Extract — continue reading at the source.
