Sometimes, the social lives of animals seem just like ours. Elephants have funerals for departed family members. Pinyon jays run collective crèches. Rats will go out of their way to help a cold, wet stranger. At other times, though, they seem fascinatingly, unrecognisably alien - like locusts, surging over the land in their millions, unable to pause for a moment because the ravening hordes behind them will literally bite their backsides off (actually, you might know a few people like that). But whatever the creature, the chances are it conducts its affairs in a way that sheds surprising new light on our own social world.