David Attenborough went up the mountain to talk about thumbs.

It was January 1978, and he was in Rwanda filming Life on Earth for the BBC. The plan was getting close to the mountain gorillas, show how they use their hands, and explain what that tells us about our own. So he crawled toward them on his hands and knees, the way you’re supposed to.

Then a female gorilla looked at him from a few feet away, and he forgot all about the thumbs. He turned to the camera and whispered, “There is more meaning and mutual understanding in exchanging a glance with a gorilla than any other animal I know.”