Brains and their changes

In Nature's "Progress" section (9/1/05): a paper by Robert Sean Hill and Christopher A. Walsh titled, "Molecular insights into human brain evolution."

Here's the abstract:

Rapidly advancing knowledge of genome structure and sequence enables new means for the analysis of specific DNA changes associated with the differences between the human brain and that of other mammals. Recent studies implicate evolutionary changes in messenger RNA and protein expression levels, as well as DNA changes that alter amino acid sequences. We can anticipate having a systematic catalogue of DNA changes in the lineage leading to humans, but an ongoing challenge will be relating these changes to the anatomical and functional differences between our brain and that of our ancient and more recent ancestors.

That would be my part, the "ongoing challenge".

The review hits the high points of comparative neuroscience, and is basically a catalog of facts. Here's one I didn't remember:

AHI1, which is essential for axon pathfinding from the cortex to the spinal cord (and hence for normal coordination and gait), is another gene that causes a neurological disease when mutated, but for which subtler changes between primate species suggest positive evolutionary selection in the lineage leading to humans. Patients with AHI1 mutations not only show mental retardation, but can also show symptoms characteristic of autism, such as antisocial behaviour. This raises the intriguing possibility that evolutionary differences in AHI1 may relate not only to human patterns of gait, but potentially species-specific social behaviour.

Overall, a concise review and worth assigning in classes.

References:

Hill RS, Walsh CA. 2005. Molecular insights into human brain evolution. Nature 437:64-67. Full text (subscription required)