In what seems like a bizarre bit of trivia, new research
indicates that people born from September to November have the best chance of
living to 100 or older.
At least that’s the case for people who are now very old. It
may not be as much the case for folks born more recently than the mid-1950s or
so.
And it may not be a useful predictor very long after birth. A lot of the
mortality that leads to the preference for fall-born kids may occur among the
very young—perhaps within the first few months of life.
It may be useful to look at the numbers backward: Kids born
in early summer—May, June and July, are far less likely than average to be
represented among centenarians.
This data comes from researchers who have previously done
Hawai`i work, although this particular research is not Hawai`i-specific. They
are Leonid A. Gavrilov and Natalia S. Gavrilova, of the University of Chicago’s
Center on Economics and Demography of Aging.
The Gavrilovs conclude that “earlylife environmental
conditions may have long-lasting effects on human aging and longevity.”
Their paper, Season of Birth and Exceptional Longevity:
Comparative Study of American Centenarians, Their Siblings, and Spouses, was
published in the Journal of Aging Research. They looked not only at U.S. data,
but found similar patterns in Europe, where the required birth and life data
are available. The paper is available here.
Aging is of interest to Hawai`i in part because Hawai`i
folks live longer than most: Island
residents can expect to live to 81.5 years, more than in any other state. Our previous post on the Gavrilov’s research is here.
The new research suggests a number of reasons for the
seeming anomaly favoring fall-born elders.
The authors suggest it could be
associated with maternal nutrition (summer-born kids were in utero during the harsh winter deprivations.) Temperature
(avoiding extremely high summer temperatures or extremely low deep winter
temperatures in the first month of
life.) The “deadline hypothesis”
(fall-born kids were older and therefore more advanced at the start of school,
gaining an education advantage on their peers that rolls into better lifelong
nutrition and opportunity and a healthier life.)
And it may also be that certain infectious diseases
affecting the very young are more likely to hit summer-born kids. A powerful
data point is that kids born in the fall don’t die of infections disease at as
high a rate as their siblings.
“According to the USA statistics, mortality below age one
month in 1940 was the lowest in September–November suggesting lower infectious
load during this period of the year, because most infant deaths in the past
were caused by infections,” the authors wrote.
© Jan TenBruggencate 2012