First, back in 2007, they found tools. Then, a bone. Now archaeologists who've continued to return to the same dig in Lingjing, China, report in the journal Science that they've unearthed more than 40 separate skull fragments to pull together two partial skulls that date back 100,000 to 130,000 years. Of particular interest? They don't fit the known patterns of Homo sapiens or Neanderthals. In fact, it looks like they might borrow bits and pieces of both, further suggesting "populational interactions," as one researcher says in a statement, which is science speak for "have enough sex to procreate." The skulls just don't seem to fit into any one category.
"I don't like to think of these fossils as those of hybrids," says one of the anthropologists, per Live Science. "Hybridization implies that all of these groups were separate and discrete, only occasionally interacting. What these fossils show is that these groups were basically not separate." Indeed, these people seemed to have the big brains of modern humans, but the prominent brow ridge and inner ear of Neanderthals. Their true origins will remain an enigma until DNA testing is successfully conducted, reports the Christian Science Monitor, which notes that they may be mysterious Denisovans, who lived around that time. Either way, the find "substantially increases our knowledge of these people," one researcher says. (Did we inherit allergies from our Neanderthal ancestors?)