WASHINGTON - A skull found in a cave in Romania includes features of both modern humans and Neanderthals, possibly suggesting that the two may have interbred thousands of years ago. Neanderthals were replaced by early modern humans. Researchers have long debated whether the two groups mixed together, though most doubt it. The last evidence for Neanderthals dates from at least 24,000 years ago. The skull bearing both older and modern characteristics is discussed in a paper by Erik Trinkaus of Washington University in St. Louis. The report appears in Tuesday's issue of Proceedings of the National Academy of Sciences. The...