In a first, researchers have sequenced genetic material from 400,000-year-old Homo erectus fossils — and the results reveal deep genetic links to both modern humans and the enigmatic Denisovans. H. erectus was the earliest human ancestor to travel outside Africa and successfully spread into Europe, Asia and Oceania beginning 1.8 million years ago. With a relatively large brain and the ability to craft complex stone tools, H. erectus was the longest-lasting human ancestor until it disappeared around 108,000 years ago. But paleoanthropologists have long wondered if H. erectus overlapped and interbred with Homo sapiens , which evolved around 300,000 years ago in Africa. Two of those amino acid variants surprised the researchers — one was present in all six H. erectus individuals but not in any other human lineage, while the other was present in all H. erectus samples as well as in Denisovans , a group of archaic humans who lived in Asia and went extinct around 30,000 years ago.…