The transition from Neanderthals to modern humans in Europe occurred during a period of recurring cold climate cycles. In a new study, a team of researchers from Germany, Austria, Romania, the United States and the United Kingdom examined climate records from Carpathian stalagmites covering a period from 44,000 to 40,000 years ago, and compared the data to archaeological records of Neanderthal artifacts. They found that archaeological layers devoid of Neanderthal tools occurred at around the same time as cold periods. The findings appear in the Proceedings of the Natural Academy of Sciences.
Neanderthals were skilled hunters and had learned how to control fire, but they had a less diverse diet than modern humans, living largely on meat from the animals they had successfully pursued. These food sources would naturally become scarce during colder periods, making Neanderthals more vulnerable to rapid environmental change.
In comparison, modern humans had incorporated fish and plants into their diet alongside meat, which supplemented their food intake and potentially enabled their survival.
“The Neanderthals were the human species closest to ours and lived in Eurasia for some 350,000 years. However, around 40,000 years ago — during the last Ice Age and shortly after the arrival of anatomically modern humans in Europe — they became extinct,” said study co-author Dr. Vasile Ersek, a researcher at Northumbria University.
“For many years we have wondered what could have caused their demise. Were they pushed ‘over the edge’ by the arrival of modern humans, or were other factors involved? Our study suggests that climate change may have had an important role in the Neanderthal extinction.”
Dr. Ersek and colleagues examined stalagmites in two caves in the Carpathian Mountains, which revealed more detailed records of climate change in continental Europe than had previously been available.
“Stalagmites grow in thin layers each year and any change in temperature alters their chemical composition,” they explained.
“The layers therefore preserve a natural archive of climate change over many thousands of years.”
The layers of the Carpathian stalagmites showed a series of prolonged extreme cold and excessively dry conditions in Europe between 44,000 and 40,000 years ago.
They highlight a cycle of temperatures gradually cooling, staying very cold for centuries to millennia and then warming again very abruptly.
The team compared these paleoclimate records with archaeological records of Neanderthal artifacts and found a correlation between the cold periods — called stadials — and an absence of Neanderthal tools.
This indicates the Neanderthal population greatly reduced during the cold periods, suggesting that climate change played a role in their decline.
“Modern humans survived these cold stadial periods because they were better adapted to their environment than the Neanderthals,” the scientists concluded.
Michael Staubwasser et al. Impact of climate change on the transition of Neanderthals to modern humans in Europe. PNAS, published online August 27, 2018; doi: 10.1073/pnas.1808647115
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