Friday, May 08, 2009

A biological reprieve from life in a shoe

There was an old woman
who lived in a shoe,
she had so many children
she didn't know what to do.
She gave them all broth
without any bread;
she whipped them all soundly
and put them to bed.
--Mother Goose

Have you ever considered that menopause may be a biological boon to get us out of such sticky shoe situations? Seriously though, what is Mother Nature's point with this mixed, menopausal blessing?

Craig Packer, a professor of ecology at the University of Michigan, considered the evolutionary advantage to animals of such programmed senescence, where the ovaries quit years before the rest of the body. He first looked for a 'granny effect', a survival advantage for those young animals with living grandmothers capable of assisting in their care. Baboon grandkids survived just as well whether grandma was dead or alive. Lion cubs only benefited from Grandma Lioness's attention if granny could nurse the little darlings because she herself remained fertile (heaven preserve us from that!).

So why don't the females of various species just keel over at menopause? Packer concluded that the answer could be found in ''prolonged maternal investment," the dependence of young mammals on the presence of a mother who's neither frail, shoe-bound, nor dead. Baby baboons need that mother's touch through their second birthday, and it is fortunate then that a baboon mom typically lives five years past her final birthing.

On the other hand, lion cubs are independent and good to go after just one year, so mama lionesses live less than two years past the end of ovarian function. Packer then assumed that human children need their moms until age ten (what kids has he been around??), and guessed that our maternal ancestors ideally would have lived until age sixty--ten years past the end of reproductive cycling--in order to see the last little darling out the door.

And now, with current advances in medical care and nutrition, we can anticipate successfully nurturing our children until they themselves are sixty!*
*Or more. My 90 year old patient spent the first half of her annual exam appointment two weeks ago fretting over her 70 year old son who still walks from his house next door to hers each evening for her home cooking. Gad.


KGMom said...

Egad is right--a 70 yo man depending on a 90 yo mother for cooking!
I have a father who will be 90 this summer--and I don't rely on him for anything--not exactly the grandfather effect.

Ann of the Incredible Gift said...

My children still call me with questions at 31, 33 and 35; just not as much as they used to, which suggests that they are getting more competent at finding answers on their own. (Yay!)

My oldest made it to 37 by living in my house, and having me as her advocate in the medical maze.

In 1971 the pediatrician told me she would die before she reached her second birthday, and if she managed to reach two, she would never see ten years.

I still shudder to think what a short and unpleasant life she would have had if I had taken his advice. He said I should get her in an institution as soon as possible.