Document Type



Data on 480 Mexican adults from a town in Michoacan permit estimation of four measures of reproductive fitness: fertility, fecundity, fertility of the parents, and number of surviving siblings. Individuals were classed as high or low on each of these criteria by comparison with the median for their sex and age group, and for each of the 4 criteria the pooled high group of either sex was compared to the pooled low group of the same sex in respect to means and variances of 25 anthropometric variables. Among 392 comparisons only 33 are significant at the .05 level and only tentative conclusions concerning directional selection, stabilizing selection or diversifying selec­tion are warranted. The suggestive evidence includes: tendencies to decreased variance of limb length measurements in females of high fecundity, and greater head length in the reproductivelv more highly fit of both sexes.