Karn & Penrose 1951

Stabilizing Selection on birthweight in humans

Karn & Penrose (1951) showed that birth weight follows a normal distribution, that mortality for newborns is greater for those either under- or over-weight, and that the mean birth weight (7 lbs) coincides with that showing minimum mortality. That is, natural selection reduces the variance in birthweight, in such a way that the distribution has become stabilized around the optimum size for maximum survival.

Text material © 2004 by Steven M. Carr