Hormones and Harmony

Humanity’s igreat leap was brought on by a decrease in testosterone levels

According to fossils discovered so far, modern human beings began to appear on the planet around 200,000 years ago; about 50 millennia ago, a sudden leap occurred in human technology. They began using tools made of bones and grindstones, equipment to fish and hunt, and even learnt to use fire, all of which helped our ancient ancestors advance rapidly. Scientists have long wondered what could have led to such a sudden kickstart of human progress.

According to new research, this occurred because there was a reduction in testosterone levels in humans and they started becoming more cooperative with each other.

The study, conducted by researchers from Duke University in the US and published in Current Anthropology, argues that living together and cooperating put a premium on agreeableness and lowered aggression, and that, in turn, led to the advancement of humans as social animals. For the study, more than 1,400 ancient and modern skulls were examined. The researchers discovered that at about the same time that society was blossoming, human skulls were beginning to change. Of the over 1,400 skulls examined, 13 belonged to modern humans more than 80,000 years old, 41 to people who lived between 10,000 and 38,000 years ago, and 1,367 to 30 ethnic populations of the 20th century. They found an overall reduction in the brow ridge and shortening of the upper face over time, reflecting a reduction in testosterone action.

The researchers claim that similar phenomena have been observed among animal species. One such study, conducted among Siberian foxes, descendants of individual animals who showed less fear of humans and less aggression, began to display relatively juvenile behaviour following selective breeding for several generations.

One of the researchers, Robert Cieri, concludes on Duke University’s website, ‘If prehistoric people began living closer together and passing down new technologies, they’d have to be tolerant of each other… The key to our success is the ability to cooperate and get along and learn from one another.’

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