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Researchers at Flinders University and the University of Adelaide in Australia have discovered something interesting in some human beings. When in the womb, babies have a temporal artery that runs down the center of the forearm and usually disappears over time. However, that artery doesn’t go away as often as it used to.
Scientists say that means more adults than ever have what amounts to an additional channel of vascular tissue under the wrist. The change is a significant increase from the mid-1880s, when only 10 percent of people were born with the extra artery in place, compared to 30 percent who were born with it in the late 20th century. Scientists point to this as evidence that humans are still evolving and point out that the increase in such a short period is significant.
The median artery forms early in development in humans and carries blood down the center of the arms to feed the hands as they grow. It usually returns around eight weeks, leaving two other blood vessels known as the radial and ulnar arteries. In the research, the scientists studied 80 corpse limbs that were donated by Australians of European descent. Donors are between 51 and 101 years old when they passed away, which means they were born in the first half of the 20th century.
During the investigation, the team noted how often they found that the median artery was still capable of carrying an adequate blood supply and compared that to figures from a literature search in the past. They believe it means that natural selection favors those who hold on to the extra blood supply. The increased retention of the vessel could be due to mutated genes involved in the development of the middle artery, as a result of health problems of the mother during pregnancy, or both.
The researchers say they expect to see greater retention of the container in the coming years. They point out that if the trend continues, most people have a median artery in the forearm by 2100.
