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More humans are growing an extra blood vessel in our arm that ‘feeds’ our hands, study shows

Picturing how our species might appear in the far future often invites wild speculation over stand-out features such as height, brain size, and skin complexion. Yet subtle shifts in our anatomy today demonstrate how unpredictable evolution can be.



a man holding his hand up: Man doing a forearm stretch.


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Man doing a forearm stretch.

Take something as mundane as an extra blood vessel in our arms, which going by current trends could be common place within just a few generations.

Researchers from Flinders University and the University of Adelaide in Australia have noticed an artery that temporarily runs down the center of our forearms while we’re still in the womb isn’t vanishing as often as it used to.

That means there are more adults than ever running around with what amounts to be an extra channel of vascular tissue flowing under their wrist.

“Since the 18th century, anatomists have been studying the prevalence of this artery in adults, and our study shows it’s clearly increasing,” says Flinders University anatomist Teghan Lucas.

“The prevalence was around 10 percent in people born in the mid-1880s compared to 30 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.”

The median artery forms fairly early in development in all humans, transporting blood down the center of our arms to feed our growing hands.

At around 8 weeks, it usually regresses, leaving the task to two other vessels – the radial (which we can feel when we take a person’s pulse) and the ulnar arteries.

Anatomists have known for some time that this withering away of the median artery isn’t a guarantee. In some cases, it hangs around for another month or so.

Sometimes we’re born with it still pumping away, feeding either just the forearm, or in some cases the hand as well.

To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent.

The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century.

Noting down how often they found a chunky median artery capable of carrying a good supply of blood, they compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel’s appearance.

The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.

“This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually,” says Lucas.

We might imagine having a persistent median artery could give dextrous fingers or strong forearms a dependable boost of blood long after we’re born. 

Arm squeezes with blood pressure cuffs may help stroke recovery

After administering clot-busting drugs to treat a stroke, using blood pressure cuffs to squeeze each arm might aid recovery, a new, small Chinese study suggests.

In the technique — called remote ischemic post-conditioning — the flow of oxygen-rich blood is repeatedly interrupted and restored using blood pressure cuffs on the arms. Earlier studies have found that the technique may prevent tissue damage by helping the body handle changes in blood flow and the damage that may occur from a stroke, researchers say.

“The findings show a promising future prospect of remote ischemic post-conditioning and have important clinical implications,” said researcher Dr. Guo-liang Li, of First Affiliated Hospital of Xi’an and Jiaotong University in Xi’an, China.

“As we all know, the therapy has a lot of advantages,” he said, calling it noninvasive, easy-to-use, cost-effective and safe.

Even though clot-busting drugs have saved many stroke patients, 32% do not have a favorable outcome. This is partly because blood flow is not completely restored and vessels can clot even after clot-busting drugs are given, Li said.

“Remote ischemic post-conditioning can be a complementary treatment that can improve the prognosis in stroke patients,” he said.

This study was done in China, but Li said the technique has also been studied in the United Kingdom, France and Denmark.

For the study, Li’s team randomly assigned 68 people (average age: 65) who suffered a stroke. All were treated within 4.5 hours with a medication that dissolves blood clots called tPA. Half also received ischemic post-conditioning therapy.

Over an average of 11 days, post-conditioning participants wore blood pressure cuffs on both arms for 40 minutes, alternating cycles of inflation for five minutes and deflation for three minutes. Treatments were done twice a day.

Stroke recovery was gauged on a scale of no symptoms no significant disability despite some symptoms or slight disability. People who had no symptoms after three months were considered to have had a favorable recovery.

Seventy-two percent of those who wore the blood pressure cuff had a favorable recovery, compared with 50% of those who didn’t, the researchers found. These findings remained significant even after taking into account age, stroke severity and other factors.

During the trial, two people dropped out — one because the cuffs caused skin redness and the other because the pressure applied during the procedure was uncomfortable. Researchers don’t know how long the treatment is needed to be most effective.

They caution that ischemic post-conditioning is still experimental and isn’t something that should be tried on recovering stroke patients at home.

“In the future, more studies are needed to confirm that the combined therapy of clot-busting drugs and remote ischemic post-conditioning is safe and effective in much larger groups of people before this experimental therapy can be performed at home,” Li said.

Dr. Larry Goldstein, chairman of the Department of Neurology at the University of Kentucky, reviewed the findings.

“This single hospital study was aimed at determining whether the technique might be helpful in improving outcomes of patients with stroke