'Human Invasion' Killed Off Neanderthals

Modern humans may have ended the Neanderthals' 300,000-year dominance of Europe through sheer numbers instead of brain power, a new study claims. The researchers say the "human invasion" 40,000 years ago left the Neanderthals outnumbered 10 to 1 by the newcomers, forcing them into fierce competition for resources, the Guardian reports.

"Numerical supremacy alone may have been a critical factor" in human dominance, the researchers say, suggesting that the human influx pushed the Neanderthals to the less desirable areas of the continent and eventually into extinction. Other researchers disagree, arguing that the Neanderthals were assimilated by modern humans, not replaced. Another study found that homosapiens interbred with the older species, and that Neanderthal genes survive in people living today. (More Neanderthals stories.)