Re: There's something fishy about human brain evolution

On 21 Feb 2006 11:03:51 -0800, "Lee Olsen" <paleocity@xxxxxxxxxxx>
wrote:

Al Zeller wrote:
r norman wrote:
On Tue, 21 Feb 2006 16:43:23 +0100, "Marc Verhaegen"
<fa204466@xxxxxxxxx> wrote:


http://www.eurekalert.org/pub_releases/2006-02/nsae-tsf021706.php
Public release date: 18-Feb-2006
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Contact: Stephen Cunnane
stephen.cunnane@xxxxxxxxxxxxxx
819-821-1170
Natural Sciences and Engineering Research Council

There's something fishy about human brain evolution
Forget the textbook story about tool use and language sparking the dramatic
evolutionary growth of the human brain. Instead, imagine ancient hominid
children chasing frogs. Not for fun, but for food.

Are there any marine frogs? Frogs that utilize marine resources so they
become enriched in iodine?


Google says there are marine frogs. Some frogs are also extremely
poisonous, although I haven't found out yet if any of those were
available for Lucy to eat 3 mya.


There is one species of frog, Rana cancrivora, that can tolerate
seawater. It uses urea as part of the mechanism to maintain
osmoregulation is such circumstances even though its skin is
permeable. That is the trick used by sharks, and the coelocanth, but
nowhere else among tetrapods as far as I know.

Iodine is widely found in soil and is available in plants grown on
such soils. Iodide ions in seawater (and soil) gets oxidized to
iodine which is volatile and is found in air (about 0.7 micrograms per
cubic meter). It then rains down to be absorbed by soil. There are
areas where the soil is deficient in iodine/iodide and in those
regions, animals can suffer from thyroxine deficiency. Severe
maternal iodide deficiency does cause poor fetal growth and brain
development.

.

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