Farm Kids And January Babies Live Longer

Children of men who owned their own farms were about 60% more likely to reach 100 than children of tenant farmers, and children of farm owners were at least 4 times more likely to live to 100 than children of men who rented homes that were not attached to farms.

Geography also affected the chances that a child born in the late 19th century would live to 100: Children born in the West were about 3 times more likely than children born in the Northeast to become centenarians.

Girls born in the Midwest and South were about twice as likely as girls born in the Northeast to become centenarians, but the chances of a boy living to 100 were only about 40% better in the Midwest and only 11% better in the South.

Gavrilova and Gavrilov uncovered a complicated relationship between birth order and exceptional longevity.

First-born daughters outdo other women, and first-born sons also do well. But "seventh sons" really are lucky: Sons who have 6 or more older siblings are more likely to become centenarians than sons with 2 to 5 older siblings, and sons who are the ninth or 10th born are more likely to become centenarians than first-born sons are.

When the researchers looked at birth months, they found that 80-year-olds born in April and May have average life expectancies that are a few weeks below average and as much as 8 weeks below the average for 80-year-olds born in January.

"This stability is evident at least for the 1885-1899 birth cohorts," the researchers write. "The fact that such an early circumstance of human life as the month of birth may have a significant effect 80 years later on the chances of human survival is quite remarkable. It indicates that there may be critical periods early in human life particularly sensitive to seasonal variations in living conditions in the past (e.g., vitamin supply, seasonal exposure to infectious diseases, etc.)"