Tuesday 23 September, 2014

Modern humans have ”smaller brains” than their hunter-gatherer forebears

Published On: Mon, Jun 13th, 2011 | Evolution | By BioNews

A scientist has revealed that the brain size of modern humans has decreased.

Marta Lahr, co-director of Cambridge University”s Leverhulme Centre for Human Evolutionary Studies, also found that modern-day people are about 10 per cent smaller and shorter than their hunter-gatherer forebears, and have been accompanied by a 10 per cent decline in brain size.

“When modern humans, Homo sapiens, first appeared around 200,000 years ago they were tall and muscular,” the Herald Sun quoted Lahr, as saying.

“The fossil evidence for the next 190,000 years is patchy, but shows that humans remained tall and robust until about 10,000 years ago when many populations show reduced stature and brain size. It is a striking change.”

The Homo sapiens with the biggest brains lived 20,000 to 30,000 years ago, in Europe. Known as Cro- Magnons, they were tall with barrel chests and large jaws and teeth. Most impressive, however, were their brains, with males averaging a volume of 1500 cubic centimetres.

The male human brain has since become smaller, now averaging 1350cc, a decrease equivalent in volume to a tennis ball. The female brain has shrunk by about the same proportion.

Lahr thinks part of the answer must lie in the sheer outlay of energy required to maintain large brains — in humans it accounts for about a quarter of all the energy used by the body.

“We may have smaller brains than early humans but that does not mean we are less intelligent,” she added.

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