Lice are incredibly specialized to their habitats; a type that evolved to grasp human head hair wouldn’t survive among human pubic hair, for example. But before our ancestors lost their fur, those lice probably roamed all over their bodies. So, by looking at DNA to unravel the evolutionary history of lice, scientists have estimated that those two types diverged about 3 million years ago. However a human genetics study indicates that we lost our hair around 1.2 million years ago. Taken together, these studies suggest a range for when our ancestors lost their fur.