A pair of researchers, drawing on the experience of nearly 22,000 couples in the 19th century -- has measured the "fitness cost" of human reproduction. This is the price that parents pay in their own health and longevity for the privilege of having their genes live on in future generations. The findings, published last month in the Proceedings of the National Academy of Sciences, manage to be both predictable and surprising.
Not surprisingly, women paid a bigger price than men. Older mothers were four times as likely to die in the year after having a child than their mates. Having lots of children was especially risky. A mother of 12 had five times the risk of dying prematurely as a mother of three. Even after their child-bearing years came to an end, women who had had many children died earlier than women who had had few.
The price of parenthood wasn't trivial for men, either. Despite the obvious fact that men avoided the hazards of childbirth, fathering more children meant more risk of dying before their time, too.
Essentially what we're talking about here is chronic stress, and raising another person is about as long term and intense as it gets. Of course, kids don't get out of the family relation scot-free, as it were:
Children who lost a mother before their fifth birthdays had a 78 percent higher chance of dying before they turned age 18 than children whose mothers survived. The same effect was seen -- again, less dramatically -- after the death of a father. Children who lost a father by age 5 had a 14 percent higher risk of dying in childhood.
Not the most earth-shattering data, but no one has really ever looked at this objectively before. I suspect siblings also attempt to suck years off each other's lifespan, in an evolutionary sense, but only so far as to the genetic similarity, of which most siblings share 50% of their genes; the parent-child relation is not without this scrutiny as well, but the investment relation is slightly skewed. Grandparents, of course, have the least investment in terms of resources but probably the greatest evolutionary interest as this represents the propogation of their genetic legacy, which I assume accounts for spoiling and increased adulation.
All the more reason for parents to exercise, be rich, eat plenty of antioxidants and get a dog or two: They will help buffer the leeching effect unwitting children play upon them.
2 comments:
They may not add years to your life, but they will add life to your years!
-Bob
It doesn't surprise me at all. But then again, think of all a parent would miss. Having children may shorten your life, but it makes it oh so---interesting?
Mom
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