There are no humans that can perform feats of super-strength or control objects with their mind, but people are apparently still undergoing small but observable evolutionary changes. New work has now suggested that the prevalence of the human median artery is changing; since the late 19th century, it has increased significantly, a change that seems to be undergoing positive natural selection. The findings have been reported in the Journal of Anatomy.
The media artery can be found in the arm and provides blood to the forearm and hand. It forms in the womb, but tended to disappear once two adult arteries, the radial and ulnar arteries develop and replace the median. However, about one in three people are now retaining the median artery as well as the other two adult arteries throughout their entire lives. It seems that the median artery will soon become common in the human adult forearm, and will not pose any additional health risk to carriers. It may even have benefits.
"Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it's clearly increasing. The prevalence was around ten percent in people born in the mid-1880s compared to thirty percent in those born in the late 20th century, so that's a significant increase in a fairly short period of time, when it comes to evolution," said Dr. Teghan Lucas from Flinders University.
Lucas suggested that these findings indicate that humans are currently evolving faster than at any other time in the past 250 years.
"This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually. If this trend continues, a majority of people will have median artery of the forearm by 2100."
In this study, the researchers examined health records and dissected cadavers from individuals born in the 20th century.
Study senior author and Professor Maciej Henneberg of the University of Zurich, Switzerland, said that the median artery is beneficial because it's increasing the overall blood supply and may also be useful as a replacement artery if one is needed during surgical procedures.
"This is micro-evolution in modern humans and the median artery is a perfect example of how we're still evolving because people born more recently have a higher prevalence of this artery when compared to humans from previous generations," said Henneberg.
"We've collected all the data published in anatomical literature and continued to dissect cadavers donated for studies in Adelaide and we found about one third of Australians have the median artery in their forearm and everyone will have it by the end of the century if this process continues."