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Wikipedia is failing me, as is google at the moment, and I've had a request to explain a certain term I used a day or so ago in a community.
The term I used is "grandparent factor," though I'm not sure that's the term anthropologists use for the situation I'm thinking of. When I learned about it in anthropology years ago, it was an explanation for menopause, which traditionally happens in middle age; that is, humans become effectively infertile several decades before the end of their expected lifespan. We're the only members of the animal kingdom that experience a loss of fertility so early, so anthropologists proposed that it might be due to the grandparent factor. Less-able elderly people stayed home from the hard work of hunting and gathering, and looked after the small children who were not yet old enough to participate in that hard work, thus freeing up the parents to contribute their strength and youth to the family and community. The explanation posits that menopause is nature's way of creating an available pool of babysitters within the family, people who would have a vested interest in seeing that the children of their lineage were being cared for.
This came up in a discussion of shingles. I just found out (from
doc_mystery - it's no end of useful having doctors on one's friends list!) that shingles is not a new infection; it's the chicken-pox virus that has been hiding out in your nervous system ever since you had chicken pox as a child, and it erupts when your immune system is somehow suppressed. The interesting part is that regular exposure to chicken pox during adulthood seems to act as a booster shot, making it less likely that the person will eventually get shingles because their body will be able to fight better, even with a depressed immune system. I see a connection there. Older people who look after young kids are going to come into regular contact with chicken pox, all things being equal, so they're going to get an additional boost to their immune systems every few years. The grandparent factor offers an increase to natural immunity from shingles.
Anyone have any links to prove I'm not pulling this out of thin air?
The term I used is "grandparent factor," though I'm not sure that's the term anthropologists use for the situation I'm thinking of. When I learned about it in anthropology years ago, it was an explanation for menopause, which traditionally happens in middle age; that is, humans become effectively infertile several decades before the end of their expected lifespan. We're the only members of the animal kingdom that experience a loss of fertility so early, so anthropologists proposed that it might be due to the grandparent factor. Less-able elderly people stayed home from the hard work of hunting and gathering, and looked after the small children who were not yet old enough to participate in that hard work, thus freeing up the parents to contribute their strength and youth to the family and community. The explanation posits that menopause is nature's way of creating an available pool of babysitters within the family, people who would have a vested interest in seeing that the children of their lineage were being cared for.
This came up in a discussion of shingles. I just found out (from
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Anyone have any links to prove I'm not pulling this out of thin air?
Is it the Grandmother Hypothesis?
Date: 2008-07-22 12:36 pm (UTC)http://en.wikipedia.org/wiki/Grandmother_hypothesis
Re: Is it the Grandmother Hypothesis?
Date: 2008-07-22 12:51 pm (UTC)(no subject)
Date: 2008-07-22 12:39 pm (UTC)(no subject)
Date: 2008-07-22 12:52 pm (UTC)(no subject)
Date: 2008-07-22 03:14 pm (UTC)(no subject)
Date: 2008-07-22 03:21 pm (UTC)The link further up the thread talks about it in a lot more detail.
(no subject)
Date: 2008-07-22 03:37 pm (UTC)So the question is, just when did true menopause start? Eve of course, concieved indefinitely. Scripture records that she and Adam lived into the 700's I think and that they bore children for a good portion of that time.
Similarly, Noah is presumed to have gone on to have more children with his wife after the flood and he was 200ish I think?
The time line would be that Abraham and Sarah were several hundred years after Noah and it is the first mention of the cessation of fertility.
I don't know if you subscribe to the historical content of the Bible or not but regardless, it is compelling within the context of the theory of the evolution of late-life infertility to aide in rearing the younger generations while the able bodied adults worked/hunted
(no subject)
Date: 2008-07-22 03:38 pm (UTC)(no subject)
Date: 2008-07-22 03:45 pm (UTC)(no subject)
Date: 2008-07-22 04:47 pm (UTC)As I recall, age is not as strong a barrier to fatherhood as it is to motherhood. It is still a factor, but (exaggerating a bit) the chance of fertilizing an egg doesn't approach zero until the heart rate does.
(no subject)
Date: 2008-07-22 03:44 pm (UTC)(no subject)
Date: 2008-07-22 03:38 pm (UTC)(no subject)
Date: 2008-07-22 03:45 pm (UTC)(no subject)
Date: 2008-07-23 02:25 am (UTC)Perhaps the more relevant factor is that fertility slowed down considerably by age 40, so prehistoric grandmas had a good 10 or 15 years to help out, even though they theoretically could have conceived (had they access to the kind of reproductive technologies that we have now).
(no subject)
Date: 2008-07-23 02:35 am (UTC)Remember that one of the blessings in the Bible is, "May you live to see your children's children," and a man's days upon the earth were numbered at threescore and ten.
(no subject)
Date: 2008-07-23 03:36 am (UTC)I suppose if one really researched the anthropological literature, one could find the answer (I however, am too lazy!)
The Bible blessing could still be interpereted as meaning, "Well, if you're really lucky you can live to see 70, but that's pretty rare, boy!"
These days, the theoretical biological age limit is about 125 years. Ask doc_mystery sometime about theories of longevity. It's pretty interesting stuff.