There is, of course, good reason to view insect brains as primitive — at least quantitatively. Humans possess 100,000,000,000 brain cells. A cockroach has nearly 1,000,000 brain cells; a fruit fly, ...

A dish of living brain cells has learned to play the 1970s arcade game Pong.. About 800,000 cells linked to a computer gradually learned to sense the position of the game's electronic ball and ...