The etiology and porotic hyperostosis among the prehistoric and historic Anasazi Indians of Southwestern United States.

Porotic hyperostosis was studied in 539 crania from maize-growing prehistoric and historic groups who occupied two dissimilar ecological zones of the Plateau country of Arizona and New Mexico--canyon bottoms and sage plain. Defined as abnormal localized sieve-like structural changes involving the hematopoietic areas of the cranium, it was found in 185 (34.3%) of these skulls. More frequent in children than in adults, it shows significant frequency differences between both children and adults of the two ecological zones. The two ecological zones differ in the availability of iron in the diet; the canyon inhabitants depended heavily on maize (which interferes with iron absorption) while the sage plain people consumed more iron-rich animal products. We hypothesize that an increased dependence on maize produced more iron deficiency anemia and resulted in more porotic hyperostosis. Maize is known to have permitted a food surplus which in turn allowed for increased Southwestern population growth in marginal areas like the canyon bottoms. Heavy dependency on a single food type with consequent hematologic problems may have been an important reason for the subsequent abandonment of the Anasazi region.