Text 1078, 69 rader
Skriven 2004-12-18 06:15:00 av William Morse (1:278/230)
Ärende: Re: Convergent Evolution
================================


wirtatmar@aol.com (Wirt Atmar) wrote in
news:cpvp7t$1m7d$1@darwin.ediacara.org: 

>>Science, Vol 306, Issue 5703, 1903-1907 , 10 December 2004 
>>
> Peter quotes:
> 
>>The Mentality of Crows: Convergent Evolution of Intelligence in
>>Corvids and Apes 
>>
>>Nathan J. Emery and Nicola S. Clayton 
>>Discussions of the evolution of intelligence have focused on monkeys
>>and apes because of their close evolutionary relationship to humans.
>>Other large-brained social animals, such as corvids, also understand
>>their physical and social worlds. Here we review recent studies of
>>tool manufacture, mental time travel, and social cognition in corvids,
>>and suggest that complex cognition depends on a "tool kit" consisting
>>of causal reasoning, flexibility, imagination, and prospection.
>>Because corvids and apes share these cognitive tools, we argue that
>>complex cognitive abilities evolved multiple times in distantly
>>related species with vastly different brain structures in order to
>>solve similar socioecological problems. 
> 
> Perhaps the most important moral in this work is that it greatly
> highlights the danger of overly implying adaptive value in one
> particular structure, especially if it's the only example that you
> either have or much care to study. 
> 
> For a great long time now, people have correlated the number and depth
> of the convolutions in the mammalian neocortex with the "intelligence"
> of the species. That actually may be true, but it's also just as
> obvious that it isn't the complete story.
> 
> For the last several decades, researchers such as Irene Pepperberg
> have been demonstrating at the intelligence of birds rivals that of
> mammals, and yet there are no convolutions in the neocortex of birds
> -- simply because they don't have a neocortex. Birds, being much more
> closely related to reptiles than mammals, lack the entire mammalian
> neocortical structure. 
> 
> Clearly, the perceptual, linguistic and analytical intelligence of
> birds has been built elsewhere in the CNS, and we're not at all sure
> where. 

An excellent point. In my youth, the conventional wisdom was that birds, 
while apparently intelligent, were in fact "hard-wired", i.e. they had a 
large repertoire of behavior but were incapable of the kind of learning 
that humans could do because of our larger brain. (although I do remember 
a wonderful book - something like "1001 questions and answers about 
animals" - that had a long discussion about the intelligence of crows). 
It now appears that corvids have managed to evolve computational ability 
similar to that of primates but in a much smaller space.  This should not 
perhaps be too surprising given the weight limitations of flight and the 
length of time available for development of bird intelligence. It may be 
surprising to humans mostly because we like to think of ourselves as 
special.

Yours,

Bill Morse
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