phil osborn <philosborn@hotmail.com> Wrote:
>Let's imagine a species - of bacteria, for example - that can only reproduce
>within a narrow temperature range, although it can survive quite well over a
>much broader range. Within this species, however, there are always a few
>mutants, recessive genes, etc., for other temperature ranges scattered around.
>If the species is subject to wide fluctuations of temperature, relative to
>the reproductive range, over time spans longer than the usual time between
>dividings, then if the species is not subject to aging and has a probably
>lifespan due to other factors that is several times that of the typical
>duration of temperature swings that take it out of the reproductive range,
>then there is a good likelihood that a large enough number of the
>non-reproductive species members will be around to reduce the food supplies,
>etc., for the minority who may have the genes necessary to keep the species going.
Yes but has evolution every been able to produced a bacteria or anything else that works
that way, something that doesn't just go dormant, something that still has an active
metabolism and eats up lots of resources but can not reproduce? I'm nor sure but the only
example that springs to mind is the human female who often lives decades after reproduction
stops. However that particular example could be explained by the unusually long childhood
of the species and the large amount of nurturing that entails. It makes me think that
evolution doesn't work at the level of the group or even primarily at the individual level,
I think the struggle for existence is fought at the gene level. Mostly.
As for aging, it seems to me it's always a negative, it's just not negative enough for
evolution to change. A bug will probably get eaten within a year anyway so there's
little point in maintaining the organism so well it could live longer than that, better to reduce
the maintenance budget and increase the reproduction budget and have lots of offspring.
John K Clark jonkc@att.net
This archive was generated by hypermail 2b29 : Mon Oct 02 2000 - 17:34:18 MDT