Re: How do large complex brains evolve? Ask the toothed whales!

ED: I don't think that the loss of the production of a certain type of
sialic acid in humans (as shown in our genomes, human lost the gene to
produce it, but apes and mammals all still have that gene) has been proven
to be a significant factor during the encephalization process. They
removed the same gene for the production of that type of sialic acid in
mice, so that the mice would more closely resemble humans, but so far, no
results that the mice grew any smarter. My point was simply that the E.Q.
factor isn't the only thing to consider, there's also genetic factors,
because in the human brain there's five times more RNA activity than in
the chimp brain, while the human liver and chimp liver are about equally
active, RNA-wise. So there is a five fold increase in RNA activity in the
brains of humans as compared with chimps. That kind of difference is not
E.Q-able, but has been measured biochemically and is related to genomic
differences.

I brought up the evoultionary record of increasing encepahlization among
toothed-whale species simply to demonstrate that a growth in E.Q. over
time not only happened to the lineage leading to homo, but also occurred
in that other mammalian lineage, in the sea. So brain growth and E.Q.
growth over geological time are not unparalleled in the fossil record.
Genus homo is not alone in that respect.

"jack syme" <drsyme@cablespeed.com> writes:
>Thanks for sending the reference to sialic acid, I will look more into it
>later.
>
>I was familiar with the research you just sited on whale encephalization,
>in
>fact I had obliquely referred to it on earlier posts with Glenn regarding
>the "wee people".
>
>My point is that encephalization is a good relative measurement of
>intelligence between species. But is not a good measurement within
>species,
>and measures nothing except intelligence. It has little or nothing to do
>with spirituality.
>
>here is a site you might find interesting.
>
>http://www.brainmuseum.org/
>
>The doplphin brain, even if close to relative brain size, does not
>appear
>at all similar to human brains. Like I have mentioned before, assuming
>that
>brain functions map to similar locations in human and dolphin brains, the
>part of the brain in the dolphin that is enlarged is, at least in humans,
>where sound and vision, are processed and patterns are recognized. i.e.
>the
>brain is enlarged there for echolocation in whales. I am not at all
>surprised that they can recognize themselves in a mirror. It is also
>where
>we understand language, among other things. But we have larger frontal
>lobes, partly to produce language, but for other things also, planning,
>foresight, etc.
>
>
>Again this leads to my question, which comes first the anatomic variation
>or
>the ability?
>
>
>
Received on Sat Nov 6 00:19:41 2004