FERTILITY AND MORTALITY DIFFERENTIALS AND THEIR IMPLICATIONS FOR MICROEVOLUTIONARY CHANGE AMONG THE CASHINAHUA

Measures of fertility and mortality among 24 Peruvian Cashinahua women and their offspring were used to determine individual variation in a number of parameters. Crow's Index of Total Selection indicated that selection potential was in the range usually found for technologicallysimple groups; the component due to mortality was six times that due to differential fertility. Individual variation in the numbers of abortion was markedly higher than for pregnancies, births, or neonatal and postnatal deaths. Spontaneous abortion showed somewhat greater differentials than did induced abortions, though both were very high. The selection potential due to embryonic mortality is considerably less than that due to postnatal mortality, but at least as great as that due to differential fertility.