"The New Yorker:" Human Biodiversity is real & humane

A South Asian anthropologist complains, reasonably, that infant growth norms based on whites cause his race to worry too much.

From The New Yorker:

Annals of Inquiry

Medical Benchmarks and the Myth of the Universal Patient

From growth charts to anemia thresholds, clinical standards assume a single human prototype. Why are we still using one-size-fits-all health metrics?

By Manvir Singh

Manvir Singh, an assistant professor of anthropology at the University of California, Davis, has written for The New Yorker since 2022. He is the author of “Shamanism: The Timeless Religion.”

March 24, 2025

Universal health standards inform the way we define malnutrition, obesity, growth abnormalities, and more, underpinning broad statistical claims. But they don’t account for human diversity.

New parents tend to be obsessed over how their babies are doing. But data on babies’ growth tends to come from Yellow Springs, Ohio in the mid-20th Century, which isn’t representative of the New, Improved America, much less of the World.

When my daughter was ten and a half months old, she qualified as “wasted,” which UNICEF describes as “the most immediate, visible and life-threatening form of malnutrition.” My wife and I had been trying hard to keep her weight up, and the classification felt like a pronouncement of failure. Her birth weight had been on the lower end of the scale but nothing alarming: six pounds, two ounces. She appeared as a dot on a chart in which colored curves traced optimal growth; fifteenth percentile, we were told. She took well to breast-feeding and, within a month, had jumped to the twentieth percentile, then to the twenty-sixth. We proudly anticipated that her numbers would steadily climb. Then she fell behind again. At four months, she was in the twelfth percentile. At nine and a half, she was below the fifth.

Our pediatrician was worried. Ease off the lentils and vegetable smoothies, we were warned; we needed to get more calories into our babe. Ghee, peanut butter—we were to drench her food in these and other fats and wash them down with breast milk and formula.

Sounds like they are Hindu vegetarians.

And that’s what we did. When we came back a month later, though, we learned that she had dropped further—and crossed into “wasted” territory.

Was this what malnutrition looked like? She seemed to be flourishing. She was happy, adventurous, and exuberantly social, babbling incessantly and forever engaging strangers with flirtatious stares. She had cheeks as plump as the juicy clementines that she loved to eat with full-fat yogurt. Although slow to hands-and-knees crawling—scooting was her preferred means of locomotion—she was hitting most of her other milestones. She was also growing longer and longer, shooting from the twelfth percentile at birth to the thirty-sixth at ten months.

In “Adaptable: How Your Unique Body Really Works and Why Our Biology Unites Us” (Avery), Herman Pontzer, an evolutionary anthropologist at Duke University, recounts facing a similar conundrum. While Pontzer was visiting a semidesert village in northern Kenya to study the Daasanach pastoralists, a German charity representative told him that the community was being devastated by malnutrition. Charity workers had plotted the heights and weights of Daasanach children on World Health Organization charts—the same ones our pediatrician used to monitor my daughter’s growth—and determined that more than two-thirds of the kids were malnourished. As a result, families were enrolled in a nutrition program and provided with high-calorie, industrially processed supplements. Yet, as with my daughter, the numbers didn’t align with ordinary observation.

“Everywhere we went, children were running, playing, and laughing,” Pontzer writes. “Kids being kids. They didn’t seem low on energy, nor did they seem particularly short, or ‘stunted.’ ” He saw no other signs of chronic starvation, such as bloated bellies or reduced fertility among adult women. The kids were slim, but in the lanky way typical of so many East African pastoralists.

The exhaustive findings of physical anthropology are so verboten these days that when you go to look up the Daasanachs on Wikipedia, you won’t find any verbal description of what they look like.

OK, I checked Wikipedia’s account of the Dinka, who were once famous for their elongation, and Wikipedia did devote a paragraph to the height of the Dinka.

So good for them.

When Pontzer and his team tracked the growth of Daasanach children, they uncovered patterns that sharply diverged from the W.H.O. curves. At around age two, these kids gain height at rates seldom seen elsewhere in the world. At five, they stand taller, on average, than well-fed kids in Europe and North America. At the same time, they put on weight more slowly, developing lean physiques that are optimal for heat dissipation. Where the German charity diagnosed deficiency, Pontzer saw adaptation.

“Adaptable” offers an engrossing, richly informative exploration of human biological diversity.

A.K.A., human biodiversity.

By revealing how our variable bodies respond to a wide range of environments, it challenges us to rethink universal health benchmarks. These standards inform everything from how we define malnutrition and micronutrient deficiencies to how we estimate the risks of growth abnormalities, metabolic disorders, and cardiovascular dysfunction. They drive global funding priorities, shape international aid programs, and inform social policies. They guide individual clinical assessments, like my daughter’s, and underpin broad statistical claims: seventeen per cent of humans are zinc-deficient; nearly a quarter of Asian-Pacific children are stunted. Yet these benchmarks rest on a monolithic image of human health—a prototypical Homo sapiens whose vulnerabilities remain unchanged across climates and genetic histories. We’ve entered the age of neurodiversity, precision medicine, and “bio-individuality,” but we still assume that malnutrition looks the same in Cologne as it does in rural Kenya. Is it time to move beyond the model of the universal patient?

… My wife and I didn’t know any of this when our daughter was first flagged for being underweight. But we had suspicions that her size might not have been as atypical as the charts implied. My wife’s family, like mine, emigrated from India. Asking around, we learned that many parents of South Asian ancestry had exceptionally small children. On Reddit forums such as r/india and r/ABCDesis, we discovered parents worrying about the same issue. Two of my wife’s cousins had been born smaller than our daughter.

I’m wondering if height and weight changes can respond to environmental changes (e.g., more nutrition) over more than one generation?

Does it take several generations for South Asians to reach their genetic potential size?

My son’s affluent Sikh friend, for example, kept growing and growing in high school, far beyond his parents’ height, and finally wound up around 6’6”.

I really don’t know what genetic height potential is for various races.

It turned out that credible research corroborated our suspicions. A series of Stanford-led studies had analyzed millions of births in the U.S. and documented a “dual paradox”: U.S.-born women of Mexican parentage, despite having higher risk profiles than U.S.-born women of Indian ancestry, are less likely to have babies with low birth weights.

The broad healthiness of not well-to-do Mexicans, even though they tend to be pudgy, is known as the Hispanic Paradox. Nobody can be quite sure of it’s explanation.

That’s one of many inconsistencies pertaining to size and nutrition. Take the so-called South Asian Enigma: India, Bangladesh, and Nepal exceed most sub-Saharan African countries on key health and development indicators, but their populations still fail to measure up (literally) to those in sub-Saharan Africa or the African diaspora.

South Asians tend to be lousy athletes.

This turned out to be surprising to me, because if you go back over a half century to the tennis boom of the early 1970s, the guy that the all-time greats had to beat in, roughly, the quarter finals of the major championships, was Indian rich kid 6’4” Vijay Armitraj.

As an adolescent, I assumed that as India became richer, its people would become taller and more athletic.

That somewhat has happened, but that mostly hasn’t happened.

For instance, Haiti’s infant-mortality rate is almost twice that of India’s, and its per-capita G.D.P. is thirty per cent lower, yet only six per cent of Haitian children are assessed as severely stunted, compared with fourteen per cent of Indian children. You find similar disparities between affluent nations in East Asia and those in northern Europe. Japan and the Netherlands are among the wealthiest countries in the world, with first-rate health care and low disease burdens, but some seven per cent of Japanese children qualify as stunted, compared with only about one per cent in the Netherlands.

The obvious takeaway is that factors aside from living standards—including biological inheritance—are the reason that Dutch and Haitian kids tower over their Japanese and Nepali peers. Yet many researchers have been wary of considering the possibility. In their efforts to resolve the South Asian Enigma, for example, they have busily investigated the effects of open-air defecation, maternal nutrition, and a preference for firstborn sons on the subcontinent. A team of economists examined whether the number of low-weight infants in sub-Saharan Africa who die skews height statistics.

According to Daniel Hruschka, an anthropologist at Arizona State University, none of these theories explain away the discrepancies. Hruschka has long had a personal interest in body measurements. “I consider myself pretty healthy, but if you use B.M.I. guidelines I am obese, and I’ve always wondered, What does that mean for my health?” he told me. The question inspired him to spend more than a decade dissecting anthropometric data, resulting in a slew of revealing findings. In research published in the twenty-tens, he confirmed that a single B.M.I. cutoff for distinguishing normal from obese body weight overestimates obesity, as defined by body fat, in populations with stockier bodies (Pacific Islanders, say) and underestimates it in leaner peoples (South Asians). What’s more, patterns in slenderness, such as similarities between closely related groups and between children and adults in the same group, strongly suggest that genetics plays a major role. In 2016, Hruschka and the anthropologist Craig Hadley, at Emory University, estimated that the standard B.M.I. cutoff misses roughly half a billion overweight people, including some two hundred and fifty million in South Asia alone.

After studying obesity, Hruschka turned his attention to height. In one of his most ambitious projects, published in 2020, he and his former student Joseph Hackman, now at the University of Utah, analyzed measurements from 1.5 million children across seventy countries. Using data on wealth, hygiene, nutrition, and infectious-disease exposure, they calculated each country’s “basal” height-for-age index—the starting height of children living under comparable environmental conditions. If the W.H.O. had been right to assume that children’s potential height is the same everywhere, basal height-for-age measurements should be consistent across populations.

They weren’t. For instance, the basal heights of children in India differed by more than a standard deviation from those of children in Haiti. Even when reared in identical environments, an Indian two-year-old would be expected to be three centimetres shorter than a Haitian two-year-old. When Hruschka and Hackman recalculated rates of severe stunting based on these findings, the estimated prevalence in Haiti more than tripled, from six per cent to twenty per cent. Similarly dramatic increases were observed in West and Central Africa. The reliance on growth charts, it seems, has hidden millions of severe stunting cases in parts of Africa.

These calculations raise another troubling possibility: estimates of stunting in other regions might be exaggerated, leading to ill-advised nutritional interventions. A 2021 study by Sachdev found that more than half of Indian children aged five to nineteen classified as “malnourished” by W.H.O. standards actually show biomarkers of obesity. “Metabolically, they are even overnourished,” Sachdev told me. Where pediatricians would normally recommend cutting back on high-calorie food for such children, “here we are pushing it,” he said.

This blindness to human variation affects children in wealthy countries, too. Though the W.H.O. charts are meant to spot “abnormal growth,” they regularly miss growth disorders in European children. It can’t help that the charts for five- to nineteen-year-olds still draw on decades-old data from the United States. In the Netherlands and Sweden, the W.H.O. charts catch only about seventy per cent of children over the age of five with growth-hormone deficiency; country-specific charts spot around ninety-five per cent. In a 2016 study of nine European nations, the W.H.O. standards consistently failed to outperform local references—except in France, which hadn’t updated its growth charts since 1979.

So charts meant to protect children’s health may be failing them across the globe, missing growth disorders in tall populations while pathologizing normal development in shorter ones.

… “Our differences are obvious, even on the surface,” Pontzer observes in “Adaptable.” “Why should our insides be any less diverse?” It’s a reasonable question.

But is it, as Matthew Yglesias would whine, an unseemly question?

… Even with these advances, Pontzer suspects another reason for the reluctance to discuss biological variation: “Differences are dangerous.” Throughout history, claims of inherent disparities have fuelled oppression, from the justification of slavery to the forced sterilization of the poor. Well-intentioned efforts to account for variation have sometimes harmed marginalized groups. Beginning in 1999, a standard equation for measuring kidney function included a “race coefficient,” which systematically overestimated kidney health in Black patients. As a result, many Black people were referred to specialists belatedly or deemed ineligible for treatments like kidney transplants. In 2021, when the National Kidney Foundation and the American Society of Nephrology recommended removing race from these calculations, more than a million Black Americans were immediately reclassified into more severe stages of kidney disease.

The failures of race-based medicine aren’t an argument for ignoring physiological diversity. Pretending that differences don’t exist doesn’t make them disappear; it only drives practitioners to rely on flawed intuitions. Familiar racial categories do a poor job of tracking ancestry and genetic variation. Yoruba people, in Nigeria, and Bench people, in Ethiopia,

Some Bench ladies wear those giant plates in their lower lip.

both qualify as Black, yet genetically they are further apart than an English person is from a Tamil.

In the 1970s, both Tamils and English were classified as Caucasian in the U.S., but then South Asian immigrants demanded to be granted the privilege of Flight From White so they could qualify for minority business development loans and racial preferences on government contracts like Oriental immigrants benefited.

Instead of clinging to dubious classifications that obscure variation, we would be better served by developing methods that account for people’s distinctive ancestry and lived environment.

True, but the U.S. government’s racial categories that are used constantly wouldn’t be a terrible start. As I may have mentioned, they are good enough for government work.

Maybe in a decade, the one-size-fits-all curves will give way to standards that recognize the different shapes of different populations, and the advice will shift to match. But, for now, we live in the space between two realities—the numbers on a spreadsheet and the child in our arms. ♦

Published in the print edition of the March 31, 2025, issue, with the headline “Beyond the Curve.”

Yeah, but that would concede that I’m not a Bad Guy, which is a big ask.

The notion, however, that I’m not actually a horrible evil person, which seem sensible to those who know me and grasp that I’m a nice guy, strikes many progressive liberals as the ditch in which they will die.