Human footprints discovered beside an ancient Mexican lake have been dated to 40,000 years ago. If the finding survives the controversy it is bound to stir up, it means that humans must have moved into the New World at least 30,000 years earlier than previously thought.
“If true, this would completely change our view of how and when the Americas were first colonised,” says Chris Stringer, head of human origins at the Natural History Museum in London, UK. But like several US experts, he is reserving judgement until the dates can be independently confirmed.