Early humans more promiscuous than modern-day people

November 4th, 2010 - 1:39 pm ICT by IANS  

London, Nov 4 (IANS) Scientists have found evidence that early humans who lived thousands of years ago were more promiscuous and competitive than the people of modern age.

A study of fossilised remains suggests that our ancient ancestors had far higher levels of male sex hormone testosterone than people living today, according to the Daily Mail.

The findings, if confirmed, mean that the cavemen were more aggressive and promiscuous and that tens of thousands of years of evolution have had a civilising influence on the human race.

The study was carried out by British and Canadian scientists who worked out the testosterone levels of extinct apes and ancestors by looking at the length of fossilised finger bones.

Previous studies have shown that exposure to testosterone in the womb can make humans and apes more aggressive and more promiscuous. The same hormones also alter the way babies develop physically in the womb.

Boys exposed to high levels tend to have a longer ring finger relative to their index finger, while in males exposed to lower levels, the two fingers tend to be of similar length.

The scientists worked out the ratio of the two finger lengths for a range of ancient hominins - or ancient members of the family tree - including four Neanderthals and an early modern human from 70,000 years ago.

They also studied the finger lengths of an ape-like ancestor called Australopithecus afarensis which lived three million years ago and an even older species called Ardipithecus ramidus from 4.4 million years ago.

The results, published in the journal Proceedings of the Royal Society B, also found that Australopithecus - a species that walked on two legs and whose best known fossil is the female nicknamed Lucy - may have been monogamous.

Ardipithecus, however, was more promiscuous - and may have behaved like modern great apes.

“It is believed that prenatal androgens (male sex hormones) affect the genes responsible for the development of the fingers, toes and the reproductive system. We have recently shown that promiscuous primate species have low index to ring finger ratios, while monogamous species have high ratios, Emma Nelson, of Liverpool University, was quoted as saying.

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