A sex-specific test of selection in utero.
We find support for the hypothesis that changes in the monthly odds of a twin among live-born males predict subsequent and opposite changes in the odds of a twin among live-born females. The hypothesis arises from the long standing argument that natural selection has conserved mechanisms by which pregnant women in stressed populations spontaneously abort fetuses least likely to yield grandchildren. Previous attempts to empirically test this argument focus almost entirely on males. We contribute to the literature by showing that, consistent with the logic of natural selection, maternal adaptations to environmental changes likely have effects on the survival of both male and female conceptuses and fetuses.
Catalano
Ralph A
RA
School of Public Health, University of California at Berkeley, 50 University Hall, Berkeley, CA 94720-7360, USA. rayc@berkeley.edu
Saxton
Katherine
K
Bruckner
Tim
T
Goldman
Sidra
S
Anderson
Elizabeth
E
D000022:Abortion, Spontaneous / Q000453:epidemiology / Q000235:genetics*; D002140:California / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000235:genetics*; D012641:Selection, Genetic; D012744:Sex Ratio; D014427:Twins / Q000235:genetics