David Greybeard and Fifi
He was the first chimpanzee to let British ethologist Jane Goodall observe him, paving the way for her landmark research on the primates in Tanzania’s Gombe Stream National Park. She watched him make fishing implements out of leaves and feast on baby bush pig, which showed scientists that humans aren’t the only ones who can make tools and that chimps eat more than just fruits and leaves. When Goodall offered him a red palm nut, he refused it, but squeezed her fingers, proving that they had an understanding without using words, as she once put it. Once David showed he was comfortable with the researcher, other chimps warmed up to her.