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Re: Trilobite handedness

Subject: Re: Trilobite handedness
From: "Edward Hennessey"
Date: Wed, 22 Feb 2006 04:21:51 GMT
Newsgroups: sci.geo.geology
"Aidan Karley"
<doIlookDAFTenoughTOpost@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote
in message
news:VA.00000c77.35e3839b@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> In article
<R0uKf.3882$JR6.2686@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
> Edward  Hennessey wrote:
> > My anticipation would be that trilobites had a preponderant
> > tendency to
> > veer right when suprised, likely demonstrating a preferential
> > "handedness"
> > in their neural development.
> >
>        Perfectly true, but since developmental biology hasn't
come to a
> consensus about *any* of handedness ... this still begs the
question of
> *why*.

The last snippet I read on the subject was contending that
left-handedness
in humans was the product of some deficiency in the prenatal
developmental process. The status of that contention could
be easily researched.

> > At another level, most people are right handed and most
> > right-handed
> > people are right legged and right eyed in terms of dominance.


> >
>        *most* is not *all*, or even *overwhelmingly*. Which is
the
> point. If it were 500:500, or 999:1, then there wouldn't be
much of a
> mystery. But since the ratio is more like 200:800 (and for the
> fieldstaff at my work, 400:600 - figure that!), then it's a lot
harder
> to explain.

Firstly, most means most.
Secondly, small populations,as you know, often have character
distributions departing from those of larger samples.

>        And I wouldn't be anything like as confident as you seem
to be
> about correlating right-handedness with right-eye dominance.
Eye
> dominance is considerable more evenly distributed than overt
handedness
> (which also tends to imply that the causative influences are
not all
> the same in handedness and eye-dominance).

Again, most means most. And I do agree with you that handedness
in eyes is less correlated with right handedness than right-leg
dominance is.

Simply, if trilobites had an overwhelming tendency to veer right
when trying to elude a predator, then predators would be
overwhelmingly ready to take advantage of that, yielding the
higher figure for right-sided trauma.

Regards,

Edward Hennessey



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