Re: [asa] Improbability of Homo Sapiens?

> For example, the large brains of humans have marked adaptive disadvantages, requiring as they do an expensive metabolism, a long gestation period, and a childhood lasting more than 25% of the average total life span.<

But the large brains also convey a variety of advantages. The exact
set of selective pressures over the history of the lineage, along with
genetic drift and other factors, will determine exactly what features
persist.

> * Being the only extant bipedal land vertebrate. Combined with an
> unusual eye-hand coordination, this permits dextrous manipulations of the
> physical environment with the hands;

Birds are also bipeds, though most have forelimbs specialized for
flight. Uniqueness does not equate to improbability; there are
numerous extinct bipedal reptiles. The hand-eye coordination seems to
relate ancestrally to primate tree-climbing; apes are fairly good at
manipulating the environment with their hands.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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