A new study suggests that ancient periods of cold and dry climate helped our speciestake the place of Neanderthals in Europe.

Researchers found that such cold periods happened at the same time Neanderthals seemed to disappear in different parts of the continent. Their disappearance was followed by the appearance of our species: Homo sapiens.

Neanderthals are a species of early humans that once lived in Europe and Asia. The species died out about 40,000 years ago. Homo sapiens arrived in Europe a few thousand years later.

Scientists have long debated what happened. Some have blamed the change in climate. Others have proposed explanations including the sudden spread of diseases and the idea that newcomers competed with the Neanderthals for resources.

Michael Staubwasser is a scientist with the University of Cologne in Germany. He and his research team reported their findings in late August in the Proceedings of the National Academy of Sciences. The researchers examined existing climate, archaeological and ecological data and added new measurements of ancient climate. Those measurements came from two caves in Romania.

Their study centered around two cold and dry periods. One began about 44,000 years ago and lasted about 1,000 years. The other began about 40,800 years ago and lasted about 600 years. The timing of those events matches the periods in which objects made by Neanderthals disappear.

“Whether they moved or died out, we can’t tell,” Staubwasser told the Associated Press.

During the two events, signs of Homo sapiens appear in sites within the Danube River Valley in central and Eastern Europe and in France, the team noted.

The changes in climate would have turned forests into grassland filled with small plants. Homo sapiens may have been better adapted to that new environment than the Neanderthals were. So they may been able to move in after Neanderthals disappeared, the researchers wrote.

Katerina Harvati is a Neanderthal expert at the University of Tuebingen in Germany. She was not involved in the study. She said it is helpful to have the new climate data from southeastern Europe. That is an area that many researchers think Homo sapiens used to spread through the continent.

But Harvati said it is unclear whether Neanderthals disappeared and Homo sapiens appeared at the times the researchers claim. She said that is because the studies they base their findings on depend on limited evidence and are sometimes disputed.

Chris Stringer is with the Natural History Museum in London. He said he thought the paper made a good case for the effect changes in climate had on Neanderthals. Yet he believes other things also led to their disappearance.

Rick Potts of the Smithsonian Institution called the study “a refreshing new look” at how one species took the other’s place.

“As has been said before, our species didn’t outsmart the Neanderthals,” Potts wrote. “We simply out-survived them.”

I’m ­Pete Musto.

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Words in This Story

species – n. a group of animals or plants that are similar and can produce young animals or plants

archaeological – adj. related to the science that deals with past human life and activities by studying the bones and tools of ancient people

ecological – adj. related to the science that deals with the relationships between groups of living things and their environments

cave(s) – n. a large hole that was formed by natural processes in the side of a cliff or hill or under the ground

adapt(ed) – v. to change your behavior so that it is easier to live in a particular place or situation

refreshing – adj. pleasantly new, different, or interesting

outsmart – v. to defeat or trick someone by being more intelligent or clever

out-survive(d) – v. to remain alive or in existence for longer or more effectively than others