Neanderthals in the western Mediterranean were not extinct due to climatic changes.

Homo Neanderthaliensis was not extinct due to climatic changes. At least, this did not happen to the various groups of Neanderthals who lived in the western Mediterranean 42,000 years ago. A research group from the University of Bologna came to this conclusion after a detailed paleoclimatic reconstruction of the last ice age through the analysis of stalagmites taken from some caves in Apulia, Italy.

The researchers focused on the Murge Karst Plateau in Apulia, where Neanderthals and Homo Sapiens coexisted for at least 3,000 years, from approximately 45,000 to 42,000 years ago. This study was published in Nature Ecology and Evolution. The data extracted from the stalagmites showed that the climatic changes that occurred during that period of time were not particularly significant. “Our study shows that this area of ​​Apulia appears as a ‘climate niche’ during the transition from Neanderthals to homo sapiens,” explains Andrea Columbu, researcher and first author of this study. “It does not seem possible that significant climatic changes occurred during that period, at least not shocking enough to cause the extinction of Neanderthals in Apulia and, therefore, in similar areas of the Mediterranean.”

The climate change hypothesis

The hypothesis that a changing climate was a factor in the extinction of Neanderthals (which happened, in Europe, almost 42,000 years ago) found considerable support among the scientific community. According to this theory, during the last ice age, sudden and rapid changes in climate were a decisive factor in the extinction of Neanderthals due to the increasingly cold and dry climate.

We can find confirmation of these abrupt changes in the analysis of the Greenland ice cores and other paleoclimatic files in continental Europe. However, when it comes to some Mediterranean areas where Neanderthals had lived for 100,000 years, the data tells a different story. The western Mediterranean is rich in prehistoric finds and, until now, nobody has carried out a paleoclimatic reconstruction of these areas occupied by Neanderthals.

The importance of stalagmites

Where to find answers about the past climate of the western Mediterranean? The research group at the University of Bologna went to the Murge plateau in Apulia. “Apulia is key to our understanding of anthropological movements: we know that both Neanderthals and Homo sapiens lived there approximately 45,000 years ago,” says Andrea Columbu. “Very few other areas in the world saw both species coexist in a relatively small space. This makes the Murge Plateau the perfect place to study the climate and biocultural underpinnings of the Neanderthal to Sapiens transition.”

How is it possible to provide a climatic reconstruction of such a remote period? Stalagmites have the answer. These rock formations rise from the floor of the karst caves thanks to the dripping of water on the roof. “Stalagmites are excellent paleoclimatic and palaeoenvironmental archives,” explains Jo De Waele, research coordinator and professor at the University of Bologna. “Since stalagmites form through dripping rainwater, they provide unquestionable evidence of the presence or absence of rain. Furthermore, they are made of calcite, which contains isotopes of carbon and oxygen. The latter provide precise information on what it was like the ground and how much it rained during the stalagmite formation period. Then we can cross-reference this data with radiometric dating, which provides an extremely accurate reconstruction of the stalagmite formation phases. “

A (relatively) stable climate

The rate at which stalagmites formed is the first significant result of this study. The researchers found that Apulian stalagmites showed a steady dripping rate in the last and previous ice age. This means that there were no abrupt changes in the climate during the millennia under investigation. A drought would have been visible on the stalagmites.

Among all the stalagmites that were analyzed, one was particularly relevant. The researchers took samples of this 50 cm long stalagmite in the Pozzo Cucù cave, in the Castellana Grotte area (Bari) and carried out 27 high-precision dating and 2,700 analyzes of stable carbon and oxygen isotopes. According to dating, this stalagmite was formed between 106,000 and 27,000 years ago. This stalagmite represents the longest timeline of the last ice age in the western Mediterranean and in Europe. Furthermore, this stalagmite showed no trace of abrupt changes in climate that could have caused the extinction of Neanderthals.

“Our analyzes show little variation in rainfall between 50,000 and 27,000 years ago, the extent of this variation is not enough to cause disturbances in the flora that inhabits the environment above the cave,” says Jo De Waele. “The carbon isotopes show that the bioproductivity of the soil remained constant during this period, which includes the 3,000 year coexistence between sapiens and Neanderthals. This means that there were no significant changes in the flora and, therefore, in the climate” .

The technological hypothesis

The results seem to show that the dramatic changes in the climate of the last ice age had a different impact in the Mediterranean area than in continental Europe and Greenland. This may discard the hypothesis that climate change is responsible for the disappearance of Neanderthals.

How do we explain its extinction after a few millennia of living with Homo Sapiens? Stefano Benazzi, paleontologist at the University of Bologna and one of the authors of the article, answers this question. “The results we obtained corroborate the hypothesis, presented by many scholars, that the extinction of the Neanderthals had to do with technology,” says Benazzi. “According to this hypothesis, Homo Sapiens hunted using technology that was far more advanced than Neanderthals,” and this represented a primary reason for Sapiens’ supremacy over Neanderthals, which eventually died out after 3,000 years of coexistence. ”

Provided by Università di Bologna