Researchers from Flinders University and the University of Adelaide in Australia have discovered something interesting in some humans. When in the womb, babies have a temporary artery running down the center of the forearm that typically fades over time. However, that artery isn’t disappearing as often as it used to.
Scientists say this means more adults than ever have what amounts to an extra channel of vascular tissue under the wrist. The change is a significant increase since the mid-1880s, when only 10% of people were born with the extra artery in place compared to 30% born with it in the late 20th century. Scientists point to this as proof that humans are still evolving and note that the increase over such a short period is significant.
The median artery forms early in development in humans and carries blood along the center of the arms to nourish the hands as they grow. It typically regresses at around eight weeks, leaving two more blood vessels known as the radial and ulnar arteries. In the research, scientists studied 80 dead limbs donated by Australians of European descent. Donors range from 51
During the search, the team noted how often they found the median artery still capable of carrying an adequate blood supply and compared it with data from a past literature search. They believe it means that natural selection favors those who keep the extra blood supply. The increased retention for the vessel could result from mutated genes involved in the development of the median artery, resulting from health problems with the mother during pregnancy, or both.
Researchers say they expect to see more vessel retention in the coming years. They note that if the trend continues, most people have a median artery in their forearm by 2100.