One of the joys of parenthood is that your kids learn things you didn't know (perhaps because no one did when you were at school).

This is a (model of) a neanderthal skull. I have tried to make it look human. Of course, neanderthals are humans (the genus), just not Homo Sapiens (the species).

Or so I thought.

But now I learn, courtesy of my daughter's project on human evolution, that DNA testing suggests that neandertals and homo sapiens interbred to such an extent that, by at least one well-known criterion of species-hood, they must be regarded as the same species.

I will refrain from any tasteless 'That explains ...' jokes.