Health

Has human evolution shrunk your brain?


There was a time when humans built great empires and developed new forms of writing starting in the 12th century BC But one question remains unanswered – Is brain size consistent with evolution? of humans?

Think again, an anthropological research team from the University of Nevada, Las Vegas (UNLV) has disproved a theory that is gaining popularity in the scientific community. This was reported in the journal Frontiers in ecology and evolution.

Inconsistencies between reports

Last year, a group of scientists made headlines when they concluded that the human brain shrank during the transition to modern urban societies some 3,000 years ago because, they say, the ability to store Our ancestors’ external storage of information in social groups reduces the need to maintain large brains. Their hypothesis, which explores decades-old ideas about modern human brain reduction evolution, is based on comparisons with evolutionary patterns seen in ant colonies.

‘The cause of the reduction in the size of the modern human brain needs to be reevaluated as the human brain has not really changed in size since our species appeared.’


UNLV anthropologist Brian Villmoare and Liverpool John Moores University scientist Mark Grabowski said. Their team analyzed the data set that the team from last year’s study used and refuted their findings.

“We were struck by the consequences of the dramatic reduction in the size of the modern human brain about 3,000 years ago, in an age of great innovation and historical significance – the emergence of the New Kingdom of Ai. Egypt, the development of Chinese writing, the Trojan War, and the emergence of the Olmec civilization, among many others,” said Villmoare.

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“We re-examined the dataset from DeSilva et al and found that human brain size has not changed for 30,000 years and probably hasn’t changed for 300,000 years,” says Villmoare. “In fact, based on this data set, we were able to identify no reduction in brain size in modern humans over any time period since the origin of our species.”

The UNLV team questioned some of the hypotheses that DeSilva et al. collected from a dataset of nearly 1,000 museum specimens and early human fossils, including:

  • The rise of agriculture and complex societies occurred at different times across the globe – meaning that there should be variations in the timing of skull changes seen in different populations. However, DeSilva’s dataset only sampled 23 crania from the critical timeframe for the brain shrinkage hypothesis and pooled the samples together from locations including the UK, China, Mali and Algeria.
  • The dataset is heavily biased because more than half of the 987 skulls examined represent only the last 100 years over a period of 9.8 million years – and so scientists don’t know the size well. how much the skull has changed over time. .
  • Many theories about what causes the modern human brain’s reduction in size need to be reevaluated if the human brain hasn’t really changed in size since our species appeared.

Source: Eurekalert

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