The Speculist

...I'm bummed:

Predictors for exceptional human longevity may include birth order, place of birth and early-life living conditions, according to a recent Society of Actuaries (SOA) study that suggests there are several factors linked to one’s longevity. The data indicates that first-born daughters are three times more likely to survive to age 100 compared to later-born daughters. The chances for exceptional longevity are minimal for sons having a birth order of four to six compared to those born earlier or later.

Although this isn't great news for me personally, there is a very nice upside: my mother, my wife, and my daughter are all first-born daughters. But why would birth order make such a difference? Randall Parker has some thoughts on that:

...one could imagine ways that a woman's body could treat an earlier pregnancy differently than a later pregnancy. During a first pregnancy a woman could have a larger store of minerals and vitamins to give to a fetus. So a woman could compensate with vitamin supplements. But alternatively the immune system of a woman's body could could respond to a succession of pregnancies differently and become poorer at avoiding immune responses to a pregnancy. That'd be harder to do something about.

That's a possibility, but it doesn't explain why daughters seem to benefit more from birth order than sons. There are environmental and other factors to be considered. Since people who live to be a hundred were all born a century ago, there's no question that a lot has changed, and that the prospects for someone born only a few decades ago might be very different from those of a person born in the late 19th or early 20th century.

Birth order and environment will probably not have the same predictive power for the longevity of younger generations as it currently does for older ones. Work is being done to skew the numbers in everyone's favor.