One of the most fascinating things about the history of life is the way distantly related species can look alike. In some cases, the similarities are superficial, and in other cases they are signs of a common ancestry. And sometimes–as in the case of our brain and the brains of worms–it’s a little of both.

The biggest feature of our brains is a massive stack of densely woven neurons called the cerebral cortex. Once our brains take in sensory information, it’s the cortex that integrates it, makes sense of it, learns from it, and decides how to respond. If you compare our cortex to those of our close relatives, the apes, they’re nearly identical in structure, although our cortex is very