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Fact Check: Humans Aren’t “Evolving a New Artery”

Photo credit: Ahad Uddin via Unsplash.

If I were starting a new online publication, I wouldn’t called it Big Think. That’s not only because the name is already taken, but because you’re setting yourself up to trip and fall. I also wouldn’t call a publication Brilliant IdeasGreat Reporting, or Amazing Insights. Because what happens when it turns out that your thinking or reporting isn’t so Big, Brilliant, Great, or Amazing after all?

Evolution in Action?

With this in mind, I turned to a headline from last week at the news site Big Think, “Humans are evolving a new artery.” Oh, really? Darwinian evolution is producing a novel functional structure before our eyes? That would be remarkable if it were true. In fact, the headline at best greatly overpromises. The author, Kristin Houser, makes that clear immediately. She calls the phenomenon mere “microevolution.”

When we think about human evolution, we’re usually pondering changes that happened over long periods of time, like the development of the fully opposable thumb or the transition to walking upright.

But scientists in Australia have now spotted evidence of a smaller, faster “microevolution” — and this change is happening in humans right now.

Microevolution in action

The microevolution has to do with an arm artery babies develop in the womb to transport blood to their forearms and hands. By the time they’re born, this artery will have been replaced by two others — usually.

However, some people are born with all three arteries, and the rate at which that’s happening is increasing dramatically, according to the Australian scientists.

After analyzing anatomical literature and dissecting the upper arms of donated cadavers, they determined that a person born in the mid-1880s had just a 10% chance of having the extra arm artery, but that someone born in the late-1900s had a 30% chance.

“This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually,” Teghan Lucas, a researcher from Flinders University, said in a press release.

Acknowledging it as micro- rather than macro-evolution is a retreat from the headline. But reading on, I realized there’s even less here. That press release from Flinders University sounded familiar. And in fact, it’s almost two years old. The article from Big Think, as it acknowledges at the end of the piece, is itself recycled from another publication, Freethink. That’s fine. But Eric H. Anderson, co-author of Evolution and Intelligent Design in a Nutshell, wrote here already about the original research after it first appeared in the Journal of Anatomy.

Not Even “Microevolution”

At the time, there were multiple other headlines ballyhooing the evidence of “evolution” at work. Anderson debunked these. It turns out what we have here isn’t “evolution.” Even “micro-evoluton” doesn’t capture it. It is what biologist Michael Behe calls “devolution.” Genes break and sometimes that provides an advantage. Other times not. Either way, it’s not the creative “evolution” that Darwin had in mind.

From, “Humans Evolving? Armed with the Evidence, the Story Breaks Down.”

Reporting in the Journal of Anatomy, scientists in Australia had uncovered that more adults now possess a “median artery of the forearm,” contrasted with studies over the past two centuries. Specifically, based on a sample of “78 upper limbs dissected at two different Australian Universities,” the researchers analyzed whether a median artery in the forearm was present. They then compared this number to those of prior studies and concluded that “the prevalence of median arteries of forearms” since 1846 had increased from approximately 10 percent to over 30 percent. The authors calculate that if the trend continues, nearly every person born after 2100 will have a median artery.

A Legitimate Cause for Concern

Prevalence of this additional artery may be of significance to modern medicine, because sometimes the “the median artery, when present, passes through the carpal tunnel, thus it can compress the median nerve, causing carpal tunnel syndrome.” Given that millions of us struggle with carpal tunnel syndrome in our device-infested world, this is potentially a legitimate cause for concern.

Setting aside for a moment the small sample size (as the authors acknowledge), let’s assume that the numbers reported in this study and in prior studies back to the mid 1800s are reflective of a genuine trend in the prevalence of the forearm median artery. Let’s further assume that the researchers’ projections for the future increase of this prevalence are spot on and that everyone born after 2100 will carry a median artery. What does this demonstrate about evolution? After all, it isn’t sufficient to simply observe a biological change and then declare that, therefore, humans are “evolving.” We must look at the underlying cause to understand what is really happening.

Regulating Embryonic Development

The authors of the study acknowledge that the cause of this change is unknown, but suggest it is likely the result of a mutation in a regulatory structure. Specifically, the median artery is “an embryonic structure, which normally regresses around the 8th week of gestation.” The median artery is therefore a perfectly normal aspect of human anatomy, present during early embryonic development and then typically fading or disappearing altogether as the radial and ulnar arteries on either side of the forearm develop and take over the job.

If we pause here and consider the facts, we can already see the clear outlines of a rational fact-based answer to the question at hand. The median artery is a normal (presumably essential) part of early embryonic development. After the artery has done its job, the developing embryo shuts down the median artery as it develops the radial and ulnar arteries. This speaks clearly to regulation and control. The kinds of things that are consistent with a planned and purposeful process. Indeed, the authors recognize that a regulated system is at work: “The mechanism for the regression of the median artery is initiated and regulated by specific genes. Persistence of the median artery into adulthood indicates the failure of the expression of these genes” (emphasis added). The researchers go on to suggest that this failure of the regression process “could have resulted from alteration of or damage to genes by mutations,” or perhaps an environmental factor, such as an infection of the mother, could have disrupted the regression process.

In either case, what we have is a carefully controlled process toward a particular outcome that has been disrupted. Unfortunately, the authors do not pursue this clear line of thinking, but instead immediately revert to the evolutionary paradigm within which they think the evidence needs to fit, arguing that the increased prevalence of the median artery “over the last 125 years means a true evolutionary process of the change in gene pools” and “the prevalence of persistent median arteries in adult forearms of people in many countries may be a trend associated with the evolutionary process.”

References to evolution are sprinkled throughout the paper. Yet despite the clear implication that the failure of median artery regression is due to a hitch in a sophisticated control process, little additional attention is paid to this fact. The authors do not mention “regulation” again, and there is no discussion of controls or outlines of additional research that could be pursued along these lines. Instead, the observations are shoehorned into a mental box of Darwinian thinking, with vague appeals to “selection pressure” as the cause of the observed change. There seems to be a collective blindness to the evidence right under our noses….

Darwin Devolves — Again

[N]o new biological structures were observed and there is no evidence that evolution produced any new biological feature. Quite the contrary. A functional structure, necessary for early embryonic development, failed to be removed when it would normally be eliminated in the developmental process. If this counts as “evolution,” as the authors say and the eager headlines proclaim, then it certainly is not evolution as Darwin envisioned it. Evolution needs to explain (and Darwin thought he was explaining) the origin of new biological features, and eventually completely new biological forms. Observing that a pre-existing structure remains on the scene after it was supposed to depart stage left tells us nothing about the structure’s origin.

Instead, what we seem to be observing in the case of the human median artery is a breakdown of a pre-existing system and a failure of a regulatory process to proceed along its pre-programmed lines. In spite of the evolutionary narrative, breakdown of existing systems and disruption of genetic programming is precisely what we can expect from mutations. If it turns out that the persistence of the median artery into adulthood is indeed the result of mutations, then what we will have is yet another example of broken genes and a broken process — another example of loss-of-function mutations, just as Michael Behe argued in Darwin Devolves

Not Evolving but Persisting

The median artery was not caught in the act of “evolving,” either in the micro- or macro- sense. It has been caught in the act of “persisting.” There are advantages and disadvantages to this. As Anderson notes, “Such de-evolutionary changes may be interesting, but they are of no comfort to the evolutionary story. Indeed, they are precisely the opposite of what evolutionary theory has to explain.” The story at Big Think, in other words, is a letdown and the headline is simply false. 

For more on what “evolution” can and can’t do, here is Michael Behe: