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Re: dinosaur copulation?
> >firstname.lastname@example.org wrote:
> >What would the selective advantage be of growing to such large size
> >after reproductive age? Remember, natural selection deals in
> >*reproduction* only. An extreme adaptation can only evolve if it
> >improves *reproduction*. Thus, a non-reproductive gigantic post-
> >adult would nt be selected for under most circumstaances.
> And yet, somehow, humans have _evolved_ so that their individual lifetimes
> _do_ exceed their reproductive lifetime, as least as far as the female half
> goes - and, considering the ramp-down in libido, etc, with advancing age,
> arguably in males as well.
Humans have not _evolved_ into this situation. It has been brought about
by both an extended family where the old are cared for and by advances
in nutrition and public health. The natural life span of a human in
either a jungle or other similar environment is around 40 to 50 years,
which corresponds remarkably closely to the reproductive life span
Life expectancies of modern peoples ion third world countries fit
very closely to this age breakdown.
Country Male Demale
Algeria 56 58
Burkino Faso 41 44
Mali 41 43
Nigeria 41 44
Senegal 41 44
As opposed to
Australia 71 78
Britain 69 75
USA 70 78
This looks much more like social and economic change than any evolutionary
change. I'm sure that a graph of life expectancy against time would show a
trend for Europe from the low forties to the seventies over a less than a
thousand year period.
I would expect that preagricultural societies would have life expectancies in
the late thirties.
> the creature is very social - in humans, it obviously was an advantage for
> a mother to stop having babies at an age when she was still capable of helping
> provide for her children and grandchildren, possibly because she was then
> removed from the dangers of childbirth and thereafter able to bridge survival
> information to a wider generation band.
The historical evidence suggests that women essentially continued having
babies until they died and that other members of the group then looked
Derek Tearne. -- email@example.com -- Fujitsu New Zealand --
Some of the more environmentally aware dinosaurs were worried about the
consequences of an accident with the new Iridium enriched fusion reactor.
"If it goes off only the cockroaches and mammals will survive..." they said.