Saturday, October 1, 2022

No, the human brain didn’t shrink 3,000 years ago

Did the 12th century BC – a time when humans were building great empires and developing new forms of written text – coincide with an evolutionary reduction in brain size? Think again, says a UNLV-led team of researchers, who refute a hypothesis that is becoming increasingly popular among the science community.

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, the social groups of our ancestors used to store information externally. The capacity of s outweighed our need to maintain large. Their hypothesis, which explored decades-old ideas on the evolutionary reduction of the size of the modern human brain, was based on a comparison of evolutionary patterns observed in ant colonies.

Not so fast, said UNLV anthropologist Brian Wilmore and University of Liverpool John Moores scientist Mark Grabowski.

In a new paper published last week Frontiers in Ecology and EvolutionThe UNLV-led team analyzed the dataset used by the research group from last year’s study and debunked their findings.

“We were struck by the effects of a substantial reduction in the size of the modern human brain about 3,000 years ago during an era of several important innovations and historical events—the appearance of the New Kingdom of Egypt, the development of the Chinese script, the Trojan War, and the Olmec civilization. emergence, among many others,” said Willmore.

“We re-examined the dataset from DeSilva et al and found that the size of the human brain hasn’t changed in 30,000 years, and probably hasn’t changed in 300,000 years,” Wilmore said. “In fact, based on this dataset, we cannot detect any reduction in brain size in modern humans in any time-period since the origin of our species.”

key takeaways

The UNLV research team questioned many of the hypotheses of DeSilva et. Al derived from a dataset of approximately 1,000 early human fossil and museum specimens, including:

  • The UNLV team says that the rise of agriculture and complex societies occurred at different times around the world – meaning that the timing of changes to the skull must have varied in different populations. However, DeSilva’s dataset sampled only 23 crania from the critical time frame for the brain shrinkage hypothesis and lumped together samples from locations including England, China, Mali and Algeria.
  • The dataset is heavily skewed because more than half of the 987 skulls examined represent only the last 100 years of the 9.8-million-year period—and so don’t give scientists a good idea of ​​what the size of the cranium is. changed. Time.
  • Many hypotheses on the reasons for the reduction in the size of the modern human brain need to be reevaluated if the human brain has not really changed in size since the advent of our species.

Story Source:

material provided by University of Nevada, Las Vegas, Original written by Keonna Summers. Note: Content can be edited for style and length.

Nation World News Desk
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