Many people have an extra artery in their arms – but it's just our continuing evolution

  • An extra artery has been found in human forearms – indicating that we're still evolving
  • According to scientists, modern humans are undergoing a 'microevolution'
  • Researchers of the new study believe that this artery has some benefits

It turns out that a "temporary" artery – developing in babies in the womb – that typically disappears over time doesn't go away as often as it used to.

According to researchers from  Flinders University and the University of Adelaide in Australia, the so-called "median artery" that runs down the centre of the forearm is being found more frequently nowadays.

This artery was typically known to regress at around eight weeks, leaving its role to two other arteries (radial and ulnar) that then develop in the arm.

The discovery came after the researchers examined 80 limbs from cadavers, all donated by Australians of European descent.

The study was published in the Journal of Anatomy.

What does this all mean?

The change represents a significant increase from the mid-1880s, when only 10% of people were born with this additional artery – compared to 30% born with it in the late 20th century – suggesting that the change is happening at an incredible pace.

The donors studied ranged from age 51 to 101 on passing, which means that the majority of them were born in the first half of the 20th century.

This artery supplies blood to the forearm and hand when a baby is formed in the mother’s womb. And in those people whose median artery doesn’t disappear, it serves to increase the blood supply to these body parts.

The researchers believe that natural selection favours those who hold onto the extra blood supply. Flinders University anatomist, Teghan Lucas, explained in a university release: “This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both, actually."

An additional benefit 

Apart from the benefit of increasing overall blood supply, it can also be used as a replacement in surgical procedures in other parts of the human body, commented senior author Professor Maciej Henneberg who is also a member of the Institute of Evolutionary Medicine at the University of Zürich, Switzerland:

“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,” Hennerbeg explained.

"If this trend continues, a majority of people will have a median artery of the forearm by 2100," said Lucas.

This is not the first kind of human anatomy found to be changing over time, indicating evolution is continuing in humans. The researchers point to a growing number of people born without wisdom teeth, and wrote that the knee bone called the fabella, is three times more common today than it was a century ago. 

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Image: Getty/MedicalRF.com

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