Human ancestors older and more widespread than previously thought

A new study of human, Neanderthal, and Denisovan genomes pushes back the date our prehistoric cousins split off from early modern humans.

What they found: Neanderthals and Denisovans came from the same lineage that split off from ours about 744,000 years ago - almost 250,000 years earlier than previous studies indicated. Roughly 300 generations later — a fairly short time, in human evolutionary terms — the Neanderthals and Denisovans split off from each other.

Why it matters: Despite a growing number of fossils and a shared genetic history, we know fairly little about our most recent ancestors. We knew that Neanderthals and Denisovans were closely related enough to interbreed with each other and humans, but much of our shared past remains murky.