kinda interesting
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"It's better to have a female than a male in stressful times," explains statistician Ralph Catalano of the University of California Berkeley. He argues that weak males are unlikely to survive to reproductive age or, if they do, are unlikely to be able to win mates over more robust males. "If you have a daughter, [her] reproductive success is not contingent on robustness because males are not as picky," he adds.
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Looking at records from 1751 to 1912--the last group of Swedes born whose overall lifespan can be reliably calculated--the researchers found that there was an inverse relationship between the sex ratio and life expectancy: "When you have more males, those males don't live as long," Catalano explains. "When you get fewer males, they tend to live longer." This supports the hypothesis that stress just prevents weaker male fetuses from being carried to term, the statisticians argue in a paper presenting the findings in the current issue of the Proceedings of the National Academies of Science.