If I tell you that scientists have studied the nervous system of a creature that’s half a billion years old, it’s hard to appreciate what that means. Half a billion years is, to paraphrase Douglas Adams, a vastly, hugely, mind- bogglingly big span of time, when even last week seems like an age ago.

So here’s (a concise history of) what happened since a little creature called Alalcomenaeus died:

Its body sinks to the ocean floor, gets covered in sediment and slowly turns into a stony fossil. Meanwhile, all the world’s land has time to glom together into a mega-continent called Pangaea before breaking up again. Life, was restricted to the oceans, invades the land. Plants and fungi go first, producing thin