Researchers are pointing to a third artery in the human arm as evidence that humans are continuing to evolve.
“The median artery is an artery that supplies the forearm and the hand with blood,” said Dr. Teghan Lucas, adjunct lecturer in the Department of Archeology at Flinders University.
Speaking on 980 CKNW’s Mornings With Simi, she noted that this artery is typically only prevalent during embryonic development. As the embryo continues to grow, two other arteries form, causing the median artery to regress.
“But what’s happening now is that more and more people are actually born with the median artery and retain it throughout adult life,” said Lucas.
In the 18th century, the number of adults with a median artery was less than ten per cent. Today, the prevalence is about 30 per cent.
At this rate, Lucas said 100 per cent of adult humans will have a median artery by the year 2100.
So the big question is, of course, why?
The median artery is not known to provide any evolutionary advantage to those who possess one. The key is that it is simply not a disadvantage.
“It is an anatomical variation,” said Lucas. “These anatomical variations are happening at an increased rate because of natural selection.”
People with “a variation from normal are no longer weeded out…because the human race has mastered our environment,” said Lucas.
In the future, researchers expect to see more anatomical variations increase in prevalence “because they cause no disadvantage.”
Lucas’ work was published in the Journal of Anatomy.
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