Medical Benchmarks and the Myth of the Universal Patient

Summary

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. 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 villag...