A fabulous bit of writing by Terry Pratchett from ‘A Hat Full of Sky’ p. 304.
‘Here is a story to believe…Once we were blobs in the sea, then fishes, and then lizards and then monkeys and hundreds of things in between… In my human mouth I has the pointy teeth of a wolf and the chisel teeth of a rabbit and the grinding teeth of a cow!… The old bit of our brains that wants to be head monkey, and attacks when it’s surprised. It reacts. It doesn’t think. Being human is knowing when not to be the monkey or the lizard or any of the other old echoes.’