Re: tree-climbing hominids
Phil Nicholls (pnich@globalone.net)
Sun, 29 Oct 1995 03:57:37 GMT
hubey@pegasus.montclair.edu (H. M. Hubey) graced us with the following
words:
>chris brochu <gator@mail.utexas.edu> writes:
>>Nope, nope, nope. A full rebuttal goes beyond the scope of
>>sci.anthro.paleo, but perhaps I should ask: How do you define "higher up
>>the evolutionary scale?"
>Brain mass divided by body mass. On this scale bacteria and
>viruses are zero. That puts us at the top.
Therefore, we are "higher up" based on a criteria that has been
specifically selected to put us on top. Does the phrase "begging the
question" mean anything to you?
Your criteria is rather simplistic for a quantitative guy like
yourself. Don't you think that there is a component of brain size
that is simply a scaling effect of body size? Don't you think that a
better approach might be to run a regression on brain size and body
size data and then look at the residuals?
Since you place such a premium on quantitative analysis you will be
pleased to know that the relationship between brain size and body size
in evolution has a rather extensive literature.
But why the emphasis on size? Why not look at the organization of
the brain which is at least as important as the increase in size?
If you do then you get yet another argument against aquatic ancestry.
Look at the brain of a whale or dolphin and the first thing you notice
is that the part of the area called the auditory association cortices
of the parietal lobe are greatly expanded when compared to a human
brain. The human brain, like any primate brain, shows enlargement of
the occipital region (where the primary visual cortex is located).
Vision is much less important to aquatic animals than hearing. None
of the endocranial casts of fossil hominids shows any evidence of an
expansion of those parts of the brain that are enlarged in aquatic
mammals.
>The first appearance on earth, if we could ascertain it, would
>be a reasonably good choice. But it would suffer from defects like
>many/most mammals alive might have gone through some change
>which can be found on the fossil records (i.e. morphological
>changes) relatively recenty and hence would tend to rank up
>there alongside of us but this would be illusionary.
This paragraph makes absolutely no sense whatsoever.
Phil Nicholls pnich@globalone.net
"To ask a question you must first know most of the answer"
-Robert Sheckley
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