Natural selective effects of ABO maternofetal incompatibility depend on age, sex and gene frequency. This study focuses on differences of fitness according to age and sex. Calculations of genotype frequencies weighted by fitness lead to the hypothesis that forces of natural selection would favor an association of excess males with type O. Studies of polymorphic populations and homogeneous·populations provide empirical support for the hypothesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.