Deformed nasal septa and relaxed selection

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Abstract
Genetic control of deformed nasal septa is evidenced in 2 studies of identical and fraternal twins, which are briefly reviewed. The frequencies of nasal septa that are deformed sufficiently to impede nasal respiration are reported in samples of skulls from 22 populations, totaling 2,353 individuals. Samples of Chinese, Egyptian, and European skulls have about twice the frequencies of abnormalities as have American Indian samples and about 3 times those of Aleuts and Eskimos. The proportion of markedly deformed to slightly deformed septa is considerably higher among the "civilized." A sample of Pueblo Indian skulls from the Southwest ranks between the "civilized" and the other Indians. Ancient Egyptians rank lower than modern Egyptians. Most cases of abnormality appear to stem from arrested development, on one side along, of a pair of ossification centers. The markedly higher frequencies of deformed septa among the samples of "civilized" populations as contrasted with the "primitives" is attributed hypothetically to a reduction in the efficacy of natural selection among the former in eliminating the genetic factors that produce septal deformities, during the many generations since their ancestors abandoned "primitive" cultures.