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Dolphin brain

Krakatoa stephan at ucla.edu
Mon Feb 1 16:13:12 EST 1999


In article <v04011701b2dbaf45ca7b@[146.226.4.215]>, rhall at uvi.edu (Richard
Hall) wrote:

> At 11:36 AM -0800 2/1/99, Krakatoa wrote:
> >In article <v04011701b2d8942d4e84@[146.226.4.215]>, rhall at uvi.edu (Richard
> >Hall) wrote:
> >> At 1:03 AM -0800 1/30/99, Michael C. Cheney wrote:
> >> >In article <v04011700b2d0b1c2274f@[146.226.4.215]>, rhall at uvi.edu (Richard
> >> >Hall) wrote:
> >> >
> >> >| Natural selection does not appear to favor humans or dolphins of extreme
> >> >| intelligence...at least there is no evidence that the mean has
> >>shifted one
> >> >| way or the other.  It is only sufficient that animals possess sufficient
> >> >
> >> >What is your basis for this statement?  Are you saying that there is no
> >> >evidence that the average human intelligence has changed throughout
> >> >evolutionary history?  What time scale are you thinking of, and what
> >> >evidence is there that it hasn't changed?
> >>
> >> rlh replies:
> >> There is no evidence that human intelligence has increased in the 50,000 -
> >> 200,000 years of homo sapiens.  Do not be fooled by the trappings of
> >> technology and benefits of economics.  Despite the accumulation of
> >
> >Well, you can also make the counterargument, there is no evidence that it
> >has not changed. In fact, I think there is considerable evidence that
> >intelligence has increased in the last 50-200,000 years. You are confusing
> >intelligence with something completely inherited (which it is clearly
> >not)  and innate;
> 
> rlh replies:
> 
> I am not confusing anything.  If your increase in "intelligence is not
> heritable, then that "increase" is merely a manifestation of something
> already there.  We are supposedly discussing the evolution of intelligence
> in various species.   If natural selection is acting on intelligence, by
> definition that critical component must be heritable.  I would be willing
> to agree that social change and technology shapes manifestations of
> intelligence but how could that be quantified as an increase in
> intelligence?
> 
> There is simply no credible evidence EITHER way and I feel the conservative
> interpertation that no change has occurred is more likely to be tested than
> the more generous interperation for reasons outlined.  There is no evidence
> that humans are more intelligent today.   Ditto dolphin intelligence.
> 
> rlh
> 
> rlh
> Richard Hall
> Comparative Animal Physiologist
> Division of Sciences and Mathematics
> University of the Virgin Islands
> St. Thomas, USVI  00802
> 
> 809-693-1386
> rhall at uvi.edu

The fact that you are writing this post is ample evidence that
intelligence has in fact increased; humans of 50-200,000 years ago were
completely incapable of this behavior or this level of analysis in any
way; they would score lower on any intelligence test, even one that was
designed for them. There is no legimate intelligence defintion you could
use which would not give you that humans today are more intelligent. You
choose to reject this because you know that human biology probably has not
changed much over the same time period, but this is not a good reason to
reject it. I could take two identical twins, raise one in an isolated
impoverished prison, and the other at Oxford, and the Oxford raised twin
would be MUCH MORE intelligent than the one raised in a prison. I don't
think I need to repeat this point.

The fact that it has increased does not necessarily reflect heritability. 
Because intelligence is completely confounded with education, and
education is socially transmitted from generation to generation, it does
not mean that the increase in intelligence over the last 50-200,000 years
is attributable to ANY change in the genetics, or that this change is
associated with reproductive fitness in any way.

So I think you should stop trying to equate intelligence to something
heritable, since studies examining this suggest that intelligence is only
partially heritable... so what is heritable?

Some traits that contribute intelligence are heritable, these components
probably include genes which contribute to the ability to learn. I would
argue there is already very good evidence that the abililtiy to learn can
strongly affect reproductive fitness, ergo, natural selection has probably
favored them.  The fact that these learning mechanisms are so highly
conserved in the entire phylum (e.g., CREB) suggests that they are very
strongly associated with fitness.

Cheers,
Stephan



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