Text 1229, 151 rader
Skriven 2004-12-29 14:54:00 av Jim McGinn (1:278/230)
Ärende: Re: Human Evolution is Ca
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EKurtz99 wrote:
> "Jim McGinn" <jimmcginn@yahoo.com> wrote
> > University of Chicago researchers now concur
> > that human evolution is categorically distinct:
>
> You mean they have finally come to their senses
> and agreed with you?

Yes, but this is not to say that they've accepted
my hypothesis for early hominid (A'pith) evolution,
at least not yet.

<snip>

> > "Humans evolved their cognitive abilities not
> > due to a few accidental mutations, but rather,
> > from an enormous number of mutations acquired
> > though exceptionally intense selection favoring
> > more complex cognitive abilities," said lead
> > scientist Bruce Lahn, an assistant professor of
> > human genetics at the University of Chicago and
> > an investigator at the Howard Hughes Medical
> > Institute.
>
> Who believes otherwise?

Paleoanthropologists (obviously).

<snip>

> > . . . a selective process that is perhaps categorically
> > different from the typical processes of acquiring new
> > biological traits."
>
> <snip>
>
> > According to Lahn, data from the Cell paper secures
> > humans' privileged position in the evolutionary
> > tree. "Human brain evolution required a major
> > overhaul of the genetic blueprint -- perhaps much
> > more so than the evolution of other biological
> > traits," he said.
>
> Maybe, maybe not. Do we know whether the same
> intensity of adaptive mutation was involved in
> the development of the senses and stealth of
> the cat? No, we don't. In the toughness and
> stamina of the wolf? No, we don't. In the flight
> control of the hummingbird or the kingfisher?
> No, again.

It would seem these researchers disagree with you
on this point.

> > But how did human ancestors encounter an
> > environment where selection for better brains
> > suddenly became such a prominent force? Lahn
> > suggests that because humans have become a
> > progressively more social species, greater
> > cognitive abilities have become more of an
> > advantage.
> >
> > "As humans become more social, differences
> > in intelligence will translate into much
> > greater differences in fitness," he said,
> > "because you can manipulate your social
> > structure to your advantage.
>
> Ah, a "Just So" story. So the driving force
> was social.

Well, that's not how I interpret these words.
It does not seem to me that they are suggesting
any specific hypothesis at all.  They are only
indicating that the evidence indicates the
emergence of very large social groups very early
in hominid evolution, large social groups not
unlike what we witness currently amongst humans.

> But Homo erectus was social, and
> was around for 2 million years with no dramatic
> increase in encephalization.

I don't dispute the stasis of HE, but this is to
overlook the fact that HE represents a major
increase in encephalization over A'pith.

> > "Even devoid of the social context, as humans
> > become more intelligent, it might create a
> > situation where being a little smarter matters
> > a lot.
>
> Ah, another story; this time it's individual
> cognitive advantage distinct from social advantage.

No, you're the one imagining the distinctness here.
The authors are simply stating that a social scenario
creates selective factors in which those that are a
little smarter have a significant advantage.

> So why the previous explanation? Because Lahn, like
> everyone else on the planet, has no idea where human
> cognitive abilities came from.

Speak for yourself.

> > "The making of the large human brain is not
> > just the neurological equivalent of making a
> > large antler.
>
> Again - who believes that big brains are the
> human equivalent of big antlers?

You are missing their point.  (And I'm too tired
to explain it to you.)

> > Rather, it required a level of
> > selection that's unprecedented,"
>
> ...unprecedented when you compare it to rats and mice.

No, compared to ANY OTHER SPECIES.

> > Lahn said. "Our study offers the first
> > genetic evidence that humans occupy a unique
> > position in the tree of life. Simply put,
> > evolution has been working very hard to
> > produce us humans."
>
> There is no such person as evolution.
> If you wish to make the case for human
> exceptionalism (and I would), you
> have to do it by looking at the behavioral
> phenotypes that set us apart - cognitive
> ability, curiosity, response to art,
> complexity of language, ability to create
> complex civilizations.

Same difference.

Jim
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