"But, of course, the Neanderthals are clearly extinct in the sense that they do not exist as an independent, separate group since some 30,000 or 40,000 years."
David Reich from Harvard Medical School coordinated the population genetic analysis of the study, which was an international effort. At the center of the research were the remains of the man, named "Oase 1," unearthed at a cave system called Peștera cu Oase in Romania.
The researchers believe that the man derived from the same expansion out of Africa as other modern people, but was likely to have been part of an early "pioneer foray into Europe," ahead of other migrations that were to come later.
Photos: Are You Related to Neanderthals?
Under what conditions his relatives, and those of other early Neanderthal-human hybrids, interbred is a big question.
Chris Stringer, an expert on early humans at the Natural History Museum in London, posed some intriguing questions about the matings.
"Were these peaceful exchanges of partners, raids which stole women or girls, or even the adoption of orphaned babies?" he asked, adding that the answer remains a mystery.