[ExI] Evolution "for the Good of the Group"
hkhenson at rogers.com
Sun Sep 21 02:59:57 UTC 2008
At 04:32 PM 9/19/2008, Jef wrote:
>... here's the pdf for your personal use.
"Is evolution a team sport, or is the
contest for survival played out
strictly between individuals?"
Trivers, Hamilton, and others showed and it was popularized by
Dawkins that evolution happens at the *gene* level. So the first
sentence is out of main stream evolutionary thinkings
no question that natural selection acts
on individual organisms: Those with
favorable traits are more likely to pass
along their genes to the next generation."
Of course as Hamilton showed, that's not the only way. Consider bees
for ghod's sake.
"But perhaps similar processes
could operate at other levels of the biological
hierarchy. In this way natural
selection could perpetuate traits that
are favorable not to an individual but
to a social unit such as a flock or a colony,"
Depends. Does the flock/colony consist of related
individuals? Again, think of bees defending a hive.
"or to an entire species, or even to
an ecosystem made up of many species.
The underlying question is: Can
biological traits evolve "for the good
of the group"?"
It depends on the group. What gets passed from generation to
generation is genes. Another example.
"Cooperative and even self-sacrificial behavior by termites is most
by selection acting at the level of the colony rather than the
individual. The image shows construction
of a tunnel linking a laboratory-maintained termite colony's nest to
a food source.
Soldier-caste termites, which are smaller and darker, take up sentry
positions facing outward
along the new trail route, while workers (larger, with light-colored
abdomens) extend the
arched tunnel. Neither of these behaviors seems likely to enhance the
survival of individual
termites compared with colony-mates that stay away from the
dangerously exposed construction
zone, but colonies in which termites build covered galleries to
protect them while foraging
have a clear advantage over colonies that lack this capacity. The
termites are of the species
So how does a termite colony reproduce? It sends out winged
reproductives. So a termite colony that had gene based behaviors
where individuals took necessary risks and were even killed in the
process of obtaining food is going to be larger than one without
these traits. Come swarming time, guess which colony sends out the
larger number of reproductives?
And evolution is the differential survival of genes.
I have made the case in "EP, memes and the origin of war" that humans
have similar psychological traits.
When the risk to the genes of an individual warrior is less than the
risk summed over his relatives multiplied by their relatedness, i.e.,
without killing the neighbors the kids will starve next dry season,
then psychological mechanisms get turned on that synch up a tribe's
warriors to make a do or die effort.
Just because someone rates as high as EO Wilson doesn't mean what he
says should be taken without examining the logic behind what his claims.
Of course this applies even more to people like me far down the feeding chain.
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