Re: Terrapins: At Well Past 100, They're in the Mood

[dinoboygraphics@aol.com]

Tommy Tyberg wrote: "The menopause most likely marks the point where 
the probability of successfully raising another child to independence 
is so low that a woman can do her inclusive fitness more good by 
helping her offspring/relatives instead."

It's not at all obvious that this is the case.  Although the 
"Grandmother Hypothesis" is popular for sociopolitical reasons 
(Lobbying by AARP..? ;-), there is remarkably little support for it. 
Problems include:

1) Little has been done to try and extend the lives of non-human 
mammals (partcularly mammals) as far beyond the natural mean as we have 
with humans; sure vets at zoos want their patients to live a long time, 
but they aren't making even a small dent compared to the time and money 
poured into extending human lives.  Without such comparative data sets, 
we can't tell if "menopause" isn't simply a form of hormonal senesence 
that many (or even all) female mammals would hit given a long enough 
lifespan.  Notably, there don't appear to be any apomorphic hormones 
that "turn on" meonopausal reactions, like you would expect if it were 
a novel adaptation.  Instead, it is the culmination of a series of 
hormone productions failing, and not always at the same time or in the 
same order.

2) The lifespans' of women (and men) were almost certainly too short 
for most of our evolutionary history for selection to take place on 
what happens to people after they are 45 or 50.  Sure, there would have 
been matriarchs (and patriarchs) who managed to live to 60, 70, or even 
80 or 90 once in a while, but their numbers were far, far to small and 
would have been swamped by breeding with the other 99% of humans.

Note that I have a grandmother and love her very much (alas, the other 
died before I was born).  This is not meant to denigrate the obvious 
emotional and humanistic importance of any individual who has been 
lucky/clever enough to live well beyond our historical life span.  I 
hope to do so myself some day.  But the scientific evidence that 
menopause is adaptive is almost completely lacking.

This is obviously getting off of dinosaurs, so for those of you who 
want to continue this discussion, please send responses to me offlist.

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com


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