Differential fertility of mothers of twins and mothers of singletons: study in Limon, Costa Rica.
The reproductive performance of mothers of twins is of interest from an evolutionary perspective. Because mothers of twins have the potential of leaving a greater number of offspring, they could be favored by natural selection. At the same time, twin pregnancies are known to be associated with higher pre- and postnatal mortality. Thus mothers of twins at least have potentially higher fertility, a potential that may be hampered by greater mortality of twins. Here, I examine the completed fertility of 149 females, 50 years of age and older, from Limon, Costa Rica. In particular, the number of surviving children of mothers of twins and mothers of singletons at the time of the interview is compared. In this sample mothers of twins have a higher fertility at the end of their reproductive career. Their selection coefficient indicates that natural selection favors them through differential fertility.
Department of Anthropology, University of South Florida, Tampa 33620, USA.
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D003364:Costa Rica; D005260:Female; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000502:physiology*; D012641:Selection, Genetic; D014427:Twins