HealthNew techniques may soon make designer babies a reality – are we ready? As tests that screen embryos for complex traits become available, it's time to decide how to use these ethically – and where to draw the line Leader
HumansEvery man in Spain was wiped out 4500 years ago by hostile invaders When a new group of people arrived on the Iberian peninsula 4500 years ago, local males stopped passing on their genes – suggesting they were supplanted or killed News