Cognitive implications: Study reveals surprising link between climate change and shrinking human brain size

A recent study by cognitive scientist Jeff Morgan Stibel of the Natural History Museum in California found a surprising link between climate change and the decline in human brain size.

By analyzing climate records and human remains spanning 50,000 years, Stibel’s research reveals how humans evolve and adapt in response to environmental stress, according to Science Alert. The findings published in the study highlight the importance of understanding the effects of climate change on human brain size and, ultimately, human behavior.

Stibel’s investigation examined 298 Homo specimens from the past 50,000 years, as well as natural records of global temperature, humidity and precipitation.

Also read | Not getting enough sleep? Your brain may be eating itself

What does the study reveal?

The results revealed a significant decrease in average brain size during periods of warmer climates compared to cooler ones. Stibel’s earlier research on brain shrinkage served as the impetus for this study as he sought to uncover the causes of the phenomenon.

In an interview with PsyPost, Mane Kara-Yakoubian Stibel emphasized the critical need to understand changes in the human brain over time. He expressed frustration at the lack of research on the topic, noting, “We know that brains have evolved across species over the past million years, but we know very little about other macroevolutionary trends.”

To compile the data, Stiebel compiled information on skull dimensions from ten published sources, resulting in 373 measurements from 298 human bones spanning 50,000 years.

To accurately estimate brain size, he adjusted for geographic region and gender when including body size estimates.

To account for potential dating errors, Stiebel classified the fossils into groups based on their age and performed the analysis using four different fossil age ranges.

In addition, he compared brain size to four climate records, including temperature data from Dome C of the European Antarctic Ice Formation Project (EPICA), which provides precise temperature measurements spanning more than 800,000 years.

Over the past 50,000 years, Earth has experienced various climate fluctuations, including the Last Glacial Maximum, a period characterized by consistently colder temperatures until the end of the Late Pleistocene. Then, during the Holocene period, the average temperature increased, leading to the present day.

Stibel’s analysis revealed a consistent pattern of brain size change in Homo that is linked to climate fluctuations as temperatures rise and fall.

Notably, across the entire Holocene warming period, which occurred about 17,000 years after the Last Glacial Maximum, average brain size declined significantly, to just over 10.7 percent.

According to Stibel, changes in brain size tend to occur thousands of years after climate change, suggesting that species-level adaptation often takes several generations. This evolutionary pattern took place over a relatively short period of 5,000 to 17,000 years, raising concerns about the possible deleterious effects of ongoing global warming on human cognition.

Stibel argues that even a small reduction in brain size in modern humans could have important physiological consequences that are not yet fully understood.

Additionally, the analysis revealed that humidity and precipitation levels also affected brain growth, although to a lesser extent compared to temperature. Dry spells were weakly correlated with slightly larger brain volumes.

While the study finds a clear link between climate change and differences in brain size, it acknowledges that climate alone does not account for all of the observed differences.

Stibel suggests that other factors, such as elements of the ecosystem, indirect climate effects (such as vegetation and net primary production), or non-climatic factors such as culture and technology, could contribute to changes in brain size.

#Cognitive #implications #Study #reveals #surprising #link #climate #change #shrinking #human #brain #size

Leave a Comment