Lab grown models of embryos, made from clusters of stem cells, are getting increasingly complex. Ethicists, regulators and ...

The human chin has been fertile ground for arguments between scientists over its purpose. As with testicles, there are half a dozen plausible ideas to explain the evolution of the human chin.

The model, which upends the decades-old "hard steps" theory that intelligent life was an incredibly improbable event, suggests that maybe it wasn't all that hard or improbable. A team of ...