October 15, 2020 | Jerry Bergman

Claims that Humans Are Evolving Fall Apart When Examined

Evidence Humans are ‘Evolving as We Speak’
Turns Out to be No Evidence for Evolution:
What is Changing is Largely the Persistence of a Nerve

by Jerry Bergman, PhD


Introduction

A new study was published on the human median artery which the authors claim offers support for evolution. The median artery is an embryonic structure located in the forearm, wrist and hand, which after birth is often dissembled and the parts recycled. The median artery follows the median nerve on its medial or lateral side. When the arm is still small, as it is in a fetus, the median artery supplies the blood needed to the arm and hand. When the arm grows in length and diameter as the fetus matures, two larger arteries are required to supply this part of the body with blood. When the other two arteries develop, the small median artery is no longer required, but in some cases may persist even after birth.

The new study reported on here found that the persistence of the median artery in postnatal life has approximately tripled over the last 125 years.[1] Why this has occurred is an interesting question but, not unexpectedly, this small variation has now been exploited by Darwinists. The longer life of the median artery is not a newly evolved trait, as they claim, but simply a variation in its persistence rate.

An extra blood vessel did not evolve, rather only its persistence changed, something very different. To put it in other terms, what they found was

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.”[2]

The researchers claim the  “prevalence was around ten 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.” Why this change occurred was speculated to be due to a mutation that damages a regulatory structure that controls the development of the artery of concern here. Attempts are made to link these slight changes to evolution when the reasons for them are unknown, but is not likely, due to the fact that mutations do not add information to the genome. In this case it appears to cause damage. Neither example in the two studies cited in this review show evidence of the changes affecting survival.

Possible Causes of the Persistence

The cause of the persistence of the median artery could be related to diet, hormones, environmental changes, new medication used, various health problems, or even differential reproduction of those with the trait. All of these factors will need to be evaluated before a likely cause of the change in the persistence rate can be postulated.

Likely, several causes are involved, and, as no other evidence has yet been found for the postulated other causes, these minor changes can be exploited by evolutionists to support their theory. One example is the study where authors speculated that this “increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually,”[3] This persistence, as Wikipedia admits, produces “an individual who does not have a median artery” yet “appears to suffer no ill effects.”[4] Nor does the individual who has a longer persistence appear to suffer ill effects. In other words, when the artery is not recycled, it does not, as far as is known, have a proven adverse effect on health or the person’s longevity. McRae even speculates that this finding supports the belief that microevolution leads to macroevolution, writing:

As small as these differences are, tiny microevolutionary changes add up to large-scale variations that come to define a species. Together they create new pressures themselves, putting us on new paths of health and disease that right now we might find hard to imagine today.[5]

McRae, admits that natural selection could work either for or against the retention of this artery. So what is being “explained” by evolutionary theory at all?

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. Yet having one also puts us at a greater risk of carpal tunnel syndrome, an uncomfortable condition that makes us less able to use our hands.[6]

Quotes from the scientists indicate that some believe the artery is retained longer in our development due to a common mutation. The reasons it regresses are logically due to room, and may be related to developmental constraints which should have been noted in the article. Thus, as McRay claims, the study found that a change as mundane as an extra blood vessel in our arms, could, according to current trends, become “common place within just a few generations.”[7]

Some Details about the Median Artery

The median artery normally regresses around the 8th week of gestation. Specifically, the median artery of the human forearm is considered an embryonic structure that supplies blood flow to the hand, and then later regresses as the radial and ulnar arteries develop.[8]

Figure 1. Median artery in the arm. Note it is divided into median cubital and median antebrachial. (Wiki Commons)

The Research Details

The researchers examined 80 limbs from cadavers aged from 51 to 101; all Australians of European descent. The first concern is that 80 is a rather small sample indicating caution when evaluating the results. They then compared the number which retained the part of the median artery that still could carry blood with records recording the number which did not retain part of the median artery from a literature search. They found the artery was “three times as common in adults today as it was more than a century ago … a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.”[9] Specifically, a total of 26 median arteries were found in 78 upper limbs obtained from Australians aged 51 to 101 years, who died in the period 2015–2016, a prevalence rate of 33.3%. Analysis of the literature showed that the presence of the median artery has been significantly increasing (p = .001) over time, from approximately 10% in people born in the mid-1880s to approximately 30% by the end of the 20th century.[10]

Because the artery is present in 35 percent of all people, this trait is considered a variant. When the median artery prevalence reaches 50 percent or more, it is considered “normal.”  If the current trend continues, the authors estimate, people born 80 years from now will all carry a median artery. The estimate is a possibility only if the current trend continues, but is dependent on many factors such as the growth rate of specific populations that have the trait. For example, the growth rate of non-Muslim Europeans is currently below replacement rate, and conversely the Muslim populations in Europe and Africa are reproducing significantly above the replacement rate. Consequently, the increase of certain anatomical variations may be increasing far more rapidly in the Muslim population compared to European populations. This is only one factor having nothing to do with Darwinian selection that can affect the prevalence of anatomical traits. Furthermore, what actually changes is when the nerve begins to regress. The median artery normally begins to regress at about the eighth week of intrauterine life but persists in many fetuses as long as to the 13th to 38th weeks, and in some cases persists in newborns, infants and even in adults.[11]

McRae correctly noted that estimates about “how our species might appear in the far future often invite wild speculation over stand-out features such as height, brain size, and skin complexion.”[12] Then he personifies evolution, writing that “subtle shifts in our anatomy today demonstrate how unpredictable evolution can be.”

One potential problem may be that this additional artery may cause adverse health effects because the “the median artery, if it passes through the carpal tunnel can compress the median nerve, causing carpal tunnel syndrome. Given that millions struggle with this problem it may be an example not of evolution, but de-evolution.

Summary of the Artery Claim

The median artery forms early in development in all humans when the arm is very tiny, transporting blood down the center of our arms to feed our growing hands. When growth has progressed to the point that the other two arteries are needed to supply the hand’s blood needs, the median artery is no longer required, thus its retention may be a problem. At around 8 weeks, it usually begins to regress, leaving the blood supply task to the radial and ulnar arteries. The radial artery is what we use to take our pulse.

This example of so-called “evolution” appears to be due simply to a mutation to the gene that regulates the regression of the median artery. If we are born with the median artery, it may later contribute to carpal tunnel syndrome. The major takeaway is there was no evidence that evolution produced any new biological structure. Furthermore the authors mention some disadvantages of the persistent artery such as potential “thrombosis, aneurysm, calcification or traumatic rupture,” and acknowledge that “a median artery is usually considered a disadvantage when complications arise due to its presence.”[13] The authors say that the only possible advantage of the persistence of the median artery could be that “in rare instances” it could be “advantageous as it can act as an ‘emergency vessel’ because, if damage to the radial or ulnar arteries occurs, it can still supply blood to the hand.”[14]

The Fabella

Some traits become less common, but later, for some reason, become more common. That is not evolution in the Darwinian sense.

Another alleged case of “evolution” in the human body was also reported recently. A diminutive bone called the fabella (Latin for “little bean”), embedded in a tendon at the back of the knee joint behind the base of the femur (thighbone), is now three times more common today than it was a century ago. This study analyzed 21,676 knees reported in 58 studies across 27 countries back to 1875.[15]

In the earliest study from 1875, fabellae were present in 17.1 percent of the population and by 1918, only 11.2 percent of humans had it, but in 2018 it went up to 39 percent – a 3.5-fold increase in persons that had the trait.[16]  The researchers noted the “fabella is a sesamoid bone located behind the lateral femoral condyle. It is common in non‐human mammals, but the prevalence rates in humans vary from 3 to 87%.”[17]

Figure 2. The fabellae bone shown in the small white structure which grows smaller as we move from left to right.

The bone variations could be due to the influence of work activity. Or it could be due simply to ethnic variations. Sesamoid bones grow larger when more force is placed on them from work stress. Another explanation is that we’re now better at detecting the fabella bone. Because it is very small, it can easily be missed, although it is more likely to be found in MRI studies.[18]

Summary of Both Articles

The most that can be claimed is that some structures vary in humans, and various factors can cause size, persistence, developmental, or other changes. These changes rarely have anything to do with Darwinism or its assumed mechanism, natural selection. In short, the story of humans evolving breaks down under scrutiny.[19] The fervor as described by Eric Anderson at Evolution News looks foolish when examined:

This past week, science readers woke up to breathless headlines about our own continuing evolution. The evidence? An extra artery in the forearm of some adults. This time it wasn’t about some obscure bird on a remote island. This was us — hard evidence that humans are still evolving! Given this personal interest factor, the story quickly spread.[20]

Likely, from what is known, the increase in the trait is caused by one or more mutations that adversely effects gene regulation. If so, it may be one more deleterious mutation that causes disease or deterioration of health.

References

[1] Lucas, Teghan; et al., 2020. Recently Increased Prevalence pf the Human Median Artery of the Forearm: A Microevolutionary Change. Journal of Anatomy 237 623–631, p. 626.

[2] McRae, Mike. 2020. “More Humans Are Growing an Extra Artery in Our Arms, Showing We’re Still Evolving.” Science Alert, October 9. https://www.sciencealert.com/more-of-us-are-growing-an-additional-artery-in-our-arm-showing-we-re-still-evolving

[3] Quoted in McRae,  2020.

[4] “Median Artery.” 2020. Wikipedia, October 12. https://en.wikipedia.org/wiki/Median_artery.

[5] McRae,  2020.

[6] McRae,  2020

[7] McRae,. 2020.

[8] Jones, N.F. and N.L. Ming. 1988. Persistent median artery as a cause of pronator syndrome. The Journal of Hand Surgery 13: 728–732.

[9] McRae, 2020.

[10] Lucas, et al., 2020. Pp. 623–631.

[11] McRae, 2020.

[12] McRae, 2020.

[13] Lucas, et al., 2020. p. 624.

[14] Lucas, et al., 2020. p. 624.

[15] Nield, David. 2019. “Mysterious Bone Discarded by Evolution Is Making a Comeback in Modern Humans.” Science Alert, April 26; https://www.sciencealert.com/a-bone-that-evolution-abandoned-is-making-a-strange-return-in-modern-humans.

[16] Berthaume, Michael, Erica Di Federico, and Anthony M. J. Bull. 2019. Fabella prevalence rate increases over 150 years, and rates of other sesamoid bones remain constant: a systematic review. Journal of Anatomy 235(1): 67-79, July.

[17] Berthaume, 2019.

[18] Berthaume, et al., 2019, p. 67.

[19] Anderson, Eric. 2020. Humans Evolving? Armed with the Evidence, the Story Breaks Down. https://evolutionnews.org/2020/10/humans-evolving-armed-with-the-evidence-the-story-breaks-down/

[20] Anderson, Eric. 2020.


Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

(Visited 322 times, 22 visits today)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.