Neanderthals probably fell victim to taller and superior Cro-Magnons rather than catastrophic climate change, researchers said on Wednesday.
Using a new method to calibrate carbon-14 dating, the international team found the last Neanderthals died at least 3,000 years before a major change in temperatures occurred.
This suggests either modern humans or a combination of humans and less severe climate change caused the species' demise some 30,000 years ago, said Chronis Tzedakis, a paleoecologist at the University of Leeds, who led the study published in the journal Nature.
"What clearly emerges from our study is we can eliminate abrupt, catastrophic climate change," he said in a telephone interview.
"It does point toward humans being involved as a factor."
Neanderthals were a dead-end offshoot of the human line who inhabited Europe and parts of west and central Asia.
Despite their image as club-carrying hairy brutes, research suggests they were expert tool-makers, used animal skins to keep warm and cared for each other.
Most researchers believe Neanderthals survived in Europe until the arrival of fully modern humans about 30,000 years ago but controversial findings last year indicated they might have survived to as recently as 24,000 years ago.
Some have used the more recent date to link the disappearance of the Neanderthals with drastic climate changes during the destruction of ice shelves that allowed modern humans to thrive, the researchers wrote.
But using radiocarbon dating on sediment samples collected from deep beneath the sea off Venezuela, the team painted a climate picture during the time of the last Neanderthals and found they died out long before such severe climate events.
The team found that even though temperatures were fluctuating 30,000 years ago, the swings were not severe and similar to climate changes Neanderthals previously withstood.
Additionally, none of the dates ranging from 24,000 to 32,000 years ago that the researchers tested corresponded with any big climate changes.
This makes it likely that a combination of climate change and the impact of humans was responsible for the disappearance of Neanderthals, Tzedakis said.
One theory is that colder weather in northern regions spurred a migration of Neanderthals and modern-day humans to southern Europe where the last known Neanderthals lived.
"They went through these climate events before and bounced back," Tzedakis said. "Climate on its own may not be the most parsimonious explanation."