This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.
Imagine that one day, you make a pact with your brother or sister, vowing to never have children of your own and instead spend your life raising theirs. You'll agree to do the grocery shopping, cook for them, clean their rooms and bathe them, until you die.
That seems like a crazy plan, but it's one that some of the most successful animals in the world - the social insects - have adopted. It's called 'eusociality' and it's a puzzle for evolutionary biologists. Why should an animal forgo the chance to reproduce in order to help rear its siblings and their young?
The strategy makes sense if you share enough genes with your close relatives. In helping them, you indirectly ...
