Amidst the recent consternation regarding IQ, race and genetics raised by the work of former University of Utah professor Henry Harpending (The Salt Lake Tribune, Jan. 4), it’s instructive to note the labeling for many diet sodas — “Phenylketonurics: Contains phenylalanine.”

Phenylketonuria (PKU) is a heritable genetic disorder that, untreated, often results in severe intellectual disability, as Pearl S. Buck poignantly described for her daughter Carol, in “The Child Who Never Grew.” A mutation in a single gene decreases the ability to process phenylalanine, a common dietary amino acid. The resultant buildup of phenylalanine can be toxic and have devastating consequences.

PKU incidence varies substantially, from one person in 200,000 (Finland) to perhaps one in 40 (in a small Roma population in Slovakia). There is no known cure. Fortunately, by restricting dietary phenylalanine, children can develop normally without PKU symptoms. Phenlyketonurics must also avoid aspartame, a common artificial sweetener that’s metabolized into phenylalanine.

So, what can we infer from this noncontroversial tidbit? Turns out, quite a lot.

For one, IQ has biological and genetic components. These vary across groups. Even small genetic differences can matter. But biology alone isn’t destiny. Neither is genetics. “Nature” and “nurture” interact, and their relative contributions aren’t fixed. Even the genetically most gifted child, deprived of all food and oxygen, ends up with an IQ of effectively zero.

So, to return to the controversy: Do genetics contribute at all to the reported higher IQs and disproportionate successes of Ashkenazi Jews in certain fields? That’s what Harpending and colleagues claimed in their 2006 article and in their otherwise often informative and intriguing book, “The 10,000 Year Explosion.”

Superficially, that may seem like a potentially reasonable question. But the repeated past misuse of science for racist ends should raise caution flags. It’s all too easy to dress up a skeleton of truth to create an entirely different character.

Proposing that the rich and poor each get what they deserve is a long-standing trope — especially among the prosperous. But Ashkenazi women carry the same mutations purported to confer intelligence (and Tay-Sachs disease) as do Ashkenazi men. So why aren’t Ashkenazi women similarly overrepresented among science Nobel Prize winners?

One obvious answer: Genetics notwithstanding, overwhelming social factors have deprived Ashkenazi women of equal opportunities — and of deserved recognition, even when they did succeed. Think Rosalind Franklin. She obtained the key crystallographic evidence for the structure of DNA that Watson and Crick used without her permission, subsequently winning the Nobel Prize.

So, too, one can’t reasonably dismiss the massive intergenerational effects that institutionalized slavery, genocide, colonization and poverty have disproportionately inflicted on several of the world’s peoples. Their consequences are enduring and warrant ongoing corrective actions.

In his 2014 Tanner Lecture at the U. and elsewhere discussing “naming rights,” Neil deGrasse Tyson similarly noted that Jews were overrepresented among Nobel Prize winners whereas Muslims were not, and asked the question, “Why?”

During the Islamic Golden Age (roughly the 9th to 12th centuries), Baghdad was an intellectual hub for much of the world, and Muslim scholars produced seminal conceptual and empirical advances. Think Arabic numerals, “al-gebra,” the birth of the scientific method and Arabic names for stars. The era’s end came from the rise of religious anti-intellectualism, the Mongol invasion, and ultimately the Christian crusades — not shifts in population genetics.

Genetic and environmental factors provide no excuse for racism. As The Tribune reported, astonishing and deeply disturbing racism and white nationalism are evident in Harpending’s later claims, compiled by the Southern Poverty Law Center. Yet even Harpending once rightly argued that genetic differences “cannot be used to justify discrimination ... People have rights and should have opportunities whatever their group.”

Buck was among the first to write publicly about familial mental disabilities, breaking a taboo and challenging a different type of discrimination. Her message conveys a broader truth. “It was my child who taught me to understand so clearly that all people are equal in their humanity and that all have the same human rights," she wrote. "None is to be considered less, as a human being, than any other, and each must be given his place and his safety in the world.”

May we together one day make it so.

| Courtesy Photo Gregory Clark

Gregory A. Clark is a local educator who has investigated the neurobiology of learning and memory in relatively smart and not-so-smart species. His views don’t necessarily reflect those of his employer, and differ decidedly from those of the similarly named economist Gregory Clark (no relation) whose work Harpending incorporates.