Discovery of extra arm artery in modern humans suggests evolution has not stopped: study

TORONTO — Researchers in Australia have discovered a physiological trend in the human body that suggests human evolution is not over.

The median artery is the main vessel that supplies blood to the human forearm and hand while in the womb, but typically disappears around the eighth week of gestation once two other arteries develop.

An investigation published in the Journal of Anatomy has found that an increasing number of adults have retained all three arteries. Scientists say this microevolutionary change in the anatomy of the human body is now present in 35 per cent of people. They predict that people born 80 years from now will all carry a median artery if the trend continues.

The presence of a median artery in an adult body was also studied back in 1995. Since then, researchers have found that it has been increasing over time from “approximately 10 per cent in people born in the mid 1880s to approximately 30 per cent by the end of the 20th century,” the study says.

Scientists say the median artery should be considered a “normal human structure” once it becomes prevalent in more than 50 per cent of adults.

“Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it’s clearly increasing,” said researcher Teghan Lucas in a statement. “This increase could have resulted from mutations of genes involved in the median artery development or health problems in mothers during pregnancy, or both actually.”

She added, “ If this trend continues, a majority of people will have median artery of the forearm by 2100.”

Over the years, researchers have discovered a small number of anatomical changes of the human body, including the increased absence of wisdom teeth. Lucas suggests that modern humans are evolving at a faster rate than at any point in the past 250 years.

The study’s co-author, professor Maciej Hennenberg, says the median artery offers benefits because it can increase overall blood supply and can be used as a replacement in surgical procedures.

“This is microevolution 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,” Hennenberg said.

He added, “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.”

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