Climate change would also have an impact on… the size of our brains

To arrive at this observation, scientist Jeff Morgan Stibel, a researcher at the National History Museum in Los Angeles, dissected the brain fossils of 298 specimens of Homo in order to assess possible changes in their size, linked to the impact of climatic variations (changes in temperature, rain, humidity, drought, etc.) over the last fifty thousand years. Published in the journal Brain, Behavior and Evolution, his study is based on data relating to the geographical origin of Homo specimens, as well as their sex. Once these analyzes were combined, the size of the brains was studied according to several ice ages.

A smaller brain

According to the results of the study, the size of the brains would have decreased by about 10.7% during the warming period of the Holocene, a still ongoing geological era that began more than 11,000 years ago. . According to Jeff Morgan Stibel, “brain size in Homo is on average significantly smaller during periods of global warming than during colder periods”. “The results suggest an adaptive response to climate change with respect to human brain size, mediated by natural selection in response to environmental stress”observes the scientist.

To a lesser extent, arid periods were associated with greater brain size compared to periods of humidity and precipitation. Temperature variations therefore seem to be the most determining climatic factor in the change in brain size. “The adaptive response appears to have begun about fifteen thousand years ago and may persist into modern times”explains Jeff Morgan Stibel.

However, the researcher points out that “Future studies will be needed to confirm any hypotheses regarding the responsiveness of brain size to climate change.” These results must indeed be interpreted with parsimony, especially since other factors unrelated to climate, such as culture and technology, could also influence the modification of the size of the human brain.