More and more adults have an extra artery in their arms, a study has found.
Scientists in Australia discovered that humans are undergoing evolution at a rapid pace. It's known as micro-evolution and it's where evolutionary changes can happen over a short period of time.
The median artery forms while a baby is in the womb and supplies blood to the forearm and hand. Normally, it disappears during gestation and is replaced by the radial and ulnar arteries.
However, it appears some people retain all three arteries into adulthood.
Advert
A research team from Flinders University in Adelaide observed a 'significant increase' in the prevalence of the median artery over time since the late 19th Century.
They analysed published records in anatomical literature and dissected cadavers from individuals who were born in the 20th Century.
The investigation was led Dr. Teghan Lucas along with Professor Maciej Henneberg and Dr. Jaliya Kumaratilake of the University of Adelaide and published in the Journal of Anatomy.
Advert
"Since the 18th Century, anatomists have been studying the prevalence of this artery in adults and our study shows it’s clearly increasing," said Dr. Lucas.
"The prevalence was around 10 per cent in people born in the mid-1880s compared to 30 per cent 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."
The authors added: “But increasing numbers of cases retain it, so a person can have all three arteries.
"People born 80 years from now will all carry a median artery if the trend continues."
Advert
The study suggests that humans are evolving faster now than at any point in the past 250 years, Dr. Lucas said.
However, the median artery is not the only example of this ongoing human evolution.
For instance, many babies are now being born without wisdom teeth. Their faces are becoming a lot shorter, with smaller jaws, meaning there is less room for teeth, Dr. Lucas pointed out.
Advert
“This is happening in time as we have learnt to use fire and process foods more," the expert noted. "A lot of people are just being born without wisdom teeth."
The study results extend to people being born with additional bones in their arms and legs or with abnormal connections of two or more bones in their feet.
The researchers believe changes in natural selection may be driving these microevolution patterns.