No, the human brain did not shrink 3,000 years ago
Last year, a group of scientists made headlines when they concluded that the human brain shrank during the transition to modern urban societies about 3,000 years ago because, they said, our ancestors’ ability to store information externally in social groups decreased our need to maintain large brains. Their hypothesis, which explored decades-old ideas on the evolutionary reduction of modern human brain size, was based on a comparison to evolutionary patterns seen in ant colonies.
Not so fast, said UNLV anthropologist Brian Villmoare and Liverpool John Moores University scientist Mark Grabowski.
In a new paper published last week in Frontiers in Ecology and Evolution, the UNLV-led team analyzed the dataset that the research group from last year’s study used and dismissed their findings.
“We were struck by the implications of a substantial reduction in modern human brain size at roughly 3,000 years ago, during an era of many important innovations and historical events — the appearance of Egypt’s New Kingdom, the development of Chinese script, the Trojan War, and the emergence of the Olmec civilization, among many others,” Villmoare said.
“We re-examined the dataset from DeSilva et al. and found that human brain size has not changed in 30,000 years, and probably not in 300,000 years,” Villmoare said. “In fact, based on this dataset, we can identify no reduction in brain size in modern humans over any time-period since the origins of our species.”
Key Takeaways
The UNLV research team questioned several of the hypotheses that DeSilva et. al gleaned from a dataset of nearly 1,000 early human fossil and museum specimens, including: