Saturday, September 02, 2006

Roy: Human Brain Evolution

pic of human, chimp brains
In Science this week is an article by Popesko, et al., reporting on an interesting genetic finding, where a particular gene sequence is duplicated in humans more than in primates, and suggests that the duplication may have something to do with being human. Macaque monkeys have 4 copies of the gene, MGC8902, whereas the more advanced chimpanzees have 10, and humans boast 49. The gene itself contains multiple copies of the domain known as DUF1220.
"In addition to labeling in the cerebellum, neuron-specific DUF1220 signals were present in the cortical layers of the hippocampus. DUF1220 domains were also abundantly expressed in neurons within the neocortex (frontal, parietal, occipital, and temporal lobes), thought to be critical to higher cognitive functions."
These researchers have previously done genome-wide scanning across species to locate another 133 genes which may have been responsible for our leap from the trees to the living room sofa (okay, so perhaps Tom's sofa antics can be explained by being a few genes shy...cursed Thetans).

The above linked page has a link to an article about yet another mind-expanding gene, MYH16, which is different in humans versus the nonhuman primates. The human version is missing 2 tiny nucleotides, resulting in smaller jaw muscles. With smaller jaw muscles, we need less skullbone for it to attach to, resulting in more room for brain expansion. Researchers have dubbed this mutation RFT, which means 'room for thought'.

It's just so far out that a handful of genes could be responsible for homo sapiens, while a number of labs are trying to add these genes to other animals -- perhaps there is a Cornelius in our future yet.

[I'd love to see what NeuroCritic has to say about this area. If you haven't checked out his site, it is an always thought-provoking, information-rich blog that is one of Blogspot's must-RSS sites.]

Other blog perspectives:
Cognitive Labs
John Hawks' Anthropology
Slashdot ...interesting discussion thread here
Modalogica ...expands on the Planet of the Apes theme (also see Slashdot discussion)


Dinah said...

Roy!! So pleased you've been unearthed, I can put away the jackhammer. I have no idea what your post is about, but I added some brains for you. I tried to put in the pic you wanted, but it wouldn't go in, hope you don't mind the brain pic substitution.
Welcome back, I got those little umbrellas for your drink.

To everyone else: see, dinah didn't do anything with Roy.

The Neurocritic said...

Roy, you've resurfaced! Thanks for the kind words. The article on DUF1220 domains is out of my area of expertise, so I won't be deconstructing that one.

John Hawks' Anthropology has the best quote:

"Nobody knows what it does. It's just a high point on a map. But what a high point:

In light of the strong DUF1220 expression we observed in neurons of the neocortex, it is intriguing that multiple independent evolutionary processes [brain enlargement, neocortex expansion, gene duplication, and domain amplification] can be seen as having individually and cumulatively contributed to increasing the DUF1220-coding potential of the human brain, suggesting that such an increase may have conferred strong selective advantages.

What the heck does it do?"

Steve & Barb said...

Dinah, thanks for the brains.
Thanks, Foo... interesting link.
And as for Neurocritic's comment (sad that I am to miss your deconstruction), I note that DUF does stand for domain of unknown function.

Ahh, but it's fun to speculate.

Sarebear said...

Re-reading dinah's comment, in one way, sounds like your post was brainless, and she brought her brains to bear and by so doing added some brains to your post . . . hee hee.