New research suggests that human beings may have been partly responsible for the disappearance of cave bears thousands of years ago.

The plant-loving animals once lived across Europe. Some experts had believed that the cooling climate during Earth's Ice Age was to blame for their extinction.

The skull of an extinct cave bear from the Natural History Museum in Belgrade, Serbia, is seen in this undated photo. (Rafal Kowalczyk/Handout via REUTERS)

Scientists reported last week they had studied genetic data from 59 cave bears. Their bones were recovered from six countries: France, Germany, Italy, Poland, Serbia, Spain and Switzerland.

From the genetic information, the scientists noted a decrease in the cave bear population beginning about 50,000 years ago. That is around the time of the arrival of Homo sapiens, or modern humans, in Eastern Europe. The researchers said they observed a sharp drop in the bears' numbers about 40,000 years ago. That coincides with the spread of Homo sapiens throughout Europe.

The animals went extinct about 20,000 years ago.

The cave bear lived in Ice Age Europe at the same time as other now extinct creatures, such as the cave lion, woolly mammoth and woolly rhinoceros. The bear was as big as a modern polar bear, but ate only plants. It appears often in prehistoric cave paintings.

There has been a scientific debate about what led to the extinction of the cave bear. Some scientists believe that the cooling climate greatly reduced the availability of the plants they needed for food. Others have blamed human activity, including hunting and taking over the caves where the bears gave birth and slept during winter.

The population decrease identified in the study began before the climate cooling connected with the most recent Ice Age, says Verena Schuenemann. She is a paleogeneticist at the University of Zurich in Switzerland.

The bear's population remained largely unchanged for long periods before that, including during two noticeably cold periods and other cooling events, she added.

Homo sapiens appeared in Africa more than 300,000 years ago and later moved to other areas. The study offered new evidence that the arrival of Homo sapiens lead to ruin for many kinds of animals across Eurasia, the Americas and Australia.

Hervé Bocherens is with the University of Tübingen in Germany. He said, "There is more and more evidence that modern humans have played a determinant role in the decline and extinction of large mammals once they spread around the planet."

Bocherens noted that Homo sapiens started moving out of Africa about 50,000 years ago. Before their arrival in Europe, the bear's population had remained strong, even while it shared its territory with another human species, the Neanderthals.

Neanderthals also went extinct after Homo sapiens arrived in Eurasia.

A report on the study appears in the publication Scientific Reports.

The Reuters news agency reported this story. Ashley Thompson adapted it for VOA Learning English. George Grow was the editor.

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