Evolution of Cognition

Harry Erwin erwin at trwacs.fp.trw.com
Thu Apr 8 15:54:57 EST 1993


My speculative posting on a possible role for sexual selection in the
evolution of human cognition received (deservedly) a certain amount of
criticism.

One point made was that sexual selection for innovativeness and
craftsmanship should result in sex-linked differences in cognition,
particularly in art. In bower birds, this is clearly present, and this
appears not the case in modern Homo sapiens. I plead guilty to this
charge--it looks like I've been cut by Ockham's razor. 

Another point was that I haven't done the necessary analyses and
simulation studies to justify my belief that modern human cognition
could not have evolved under natural selection from standard mammalian
cognition. Actually here I've done a number of studies, as have others.
Hines and Bishop showed that learning would perturb the ESS defined by
natural selection but did not claim that it would destabilize it. Huberman
and Glance have related results that also suggest that the system would
usually relax to a fixed point. My son's work came up with similar
results, even though the ESS could be expected to evolve chaotically if
the evolution were "intelligent."

My point is that learning in most mammalian species appears (IMHO) to be
"calibration." The basic behavioral patterns are biological (genetic) and
learning calibrates those patterns to the real circumstances of the local
population. Once calibrated, the system freezes. Innovation and
experimentation is thus a characteristic of youth, not adulthood. Although
a degree of skill at planning is seen in many mammals, it tends to be
short-term. Binford and Diamond both indicate that the archeological
record seems to indicate that archaic H. sapiens and H. neanderthalensis
show no evidence of an ability to develop complex plans. The stability of
culture prior to modern H. sapiens also suggests that adults were bound by
habit and learning in children was basically rote. (Great ape cultures
should provide insight into this question.) Note that there is evidence
that selective pressures on children in archaic H. groups were similar to
the selective pressures on adults (lack of adolescent growth spurt,
extended pregnancies, early adulthood).

My point is that innovation as practised by modern H. sapiens has
different dynamics from learning as seen in other species. It requires
new mechanisms in the brain. It might be neotenic, but the tendency
towards stability has to be overcome.

(I'm thinking on my feet here...) Could there have been a third selective
process involved in the evolution of innovativeness? One without a link to
the sex of the individual, but otherwise with a similar tendency towards
destabilization? The evolution of the adolescent growth spurt may be a
clue.

Back tomorrow.

-- 
Harry Erwin
Internet: erwin at trwacs.fp.trw.com
Have found some interesting work...



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