Debunking the claim that the ‘extra forearm artery’ proves evolution
Some evolutionists now claim that an extra artery increasingly found in the forearm of some humans is evidence for evolution.1
When humans develop in the womb, a single artery (the median artery) runs down their forearm. This supplies blood to the hand and forearm. At around the 8th week of pregnancy, this artery starts to disappear, via the orderly and planned cell ‘death’ called apoptosis.2 It is replaced by the radial and ulnar arteries. This is an important part of the normal developmental process.
The median artery sometimes fails to regress. In that case, the person ends up with all three arteries for life. This failure is thought to be most likely due to mutation (an accidental inherited genetic mistake), or sometimes possibly due to maternal disease during pregnancy.
Up to a third of all adults today retain this artery—making it far more common than in the past. This was according to a small sample study going back to 1846, when only about one out of nine adults had this artery.
Presuming that the increase is real, is it evidence for evolution? The extra artery is actually the opposite. It is the result of a breakdown of the mechanism that regulates the disappearance of the fetal artery. When this failure is due to a genetic defect, this is loss of information governing the process.
Despite the claim of natural selection/evolution in action, having the extra artery does not seem to give any significant survival advantage. The only real ‘advantage’ identified seems to be that surgeons are able to ‘harvest’ it for use as an arterial graft elsewhere. But this is hardly relevant to reproductive success (having more offspring, therefore favoured by selection). It is thus irrelevant to any discussion of evolution.
It is obvious from the everyday experience of most people, who only have the two arteries (radial and ulnar), that these provide ample blood supply for our forearm and hand. This has long been known to anatomists, and is further confirmed by the fact that the median artery can be safely removed for such operations.
If anything, the median artery in adults causes problems. It accompanies the median nerve in passing through the wrist’s carpal tunnel. Excess pressure on the median nerve causes the debilitating carpal tunnel syndrome suffered by millions. This often requires surgery. The presence of an extra structure (the artery) in the tunnel can make this problem more likely.
Some of the other negatives of this artery’s persistence include “thrombosis, aneurysm, calcification or traumatic rupture” of the artery.3 All are disadvantages, not advantages—the opposite of evolution.
Of course, these would likely have only a weak, if any, effect on survival/reproductive success. So, it would be expected that natural selection would be unable to remove such a mildly harmful defect from a population, allowing it to persist, and even increase—though the reasons for an increase of this magnitude (supposedly from 10% to 30% of the population) are so far unclear to researchers.
No new design feature was produced, and the only thing that seems to be happening is damage to an existing regulatory process. This is the opposite of evolution, and more in line with ‘de-evolution’.
References and notes
- Anderson, E., Humans Evolving? Armed with the evidence, the story breaks down; evolutionnews.org, 13 Oct 2020. Return to text.
- Bell, P., Apoptosis: cell ‘death’ reveals creation, J. Creation 16(1):90–102, 2001; creation.com/apoptosis. Return to text.
- Liberatore, S., Humans are STILL evolving: Scientists discover increase in the prevalence of a forearm artery that babies born before the 1800s lost after birth; dailymail.co.uk, 9 Oct 2020. Return to text.