A chimp stripping leaves off a twig overturned science's definition of what makes us human

In 1960 at Gombe Stream in Tanzania, Jane Goodall watched a chimpanzee strip the leaves from a twig, then poke it into a termite mound and withdraw it covered in insects to eat. It was among the first clear observations of a wild animal both making and using a tool, prompting her mentor Louis Leakey's famous response: 'We must now redefine man, redefine tool, or accept chimpanzees as human!'

— Jane Goodall, In the Shadow of Man — 1971; observation first made 1960
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