Reassessing 'hereditary' interethnic differences in anemia status

The widely accepted hypothesis that significant differences in hemoglobin levels exist between African Americans and European Americans is critically evaluated. Most studies implying hereditary interethnic differences are derived from analyses of national cross-sectional surveys or smaller nonprobability samples. Yet those studies give inadequate consideration to the important nutritional and genetic variables that must be controlled for in acceptable comparative assessments of the heritable component of anemia. Missing but vital nutritional variables include reliable parameters of intake, absorption, and utilization of nutrients, and preexisting nutrient stores. Actual measures of confounding genetic conditions such as alpha-thalassemia and hemoglobin variants are also absent, although pronounced within-group diversity has been observed in both macroethnic groups. The likelihood that significant interethnic differences exist in the structural genes coding for hemoglobin level is nil given our species' molecular genetics and evolutionary history. Common recent African origins for all modern humans, as suggested by the fossil and molecular data, as well as our close biochemical affinities with chimpanzees and gorillas, suggest that biologically significant differences among populations of contemporary humans are unlikely. When the proper control of relevant epigenetic and genetic variables is maintained, the reported discrepancies tend to disappear.