I've written a few articles in the past about the evolution of human brain size: Big brains, big genes (which followed up on an essay by Zimmer on The Genes Behind Big Brains), Brain size and allometry, More on ASPM and the evolution of brain size, and Adaptive evolution of ASPM. These describe a gene, ASPM, identified as causing human microcephaly. ASPM is interesting for several reasons; it's homologous to a gene in Drosophila that also regulates the amount of neural tissue in that animal, and it seems to operate by controlling the pattern of mitoses, regulating the number of cells allocated in early development of the brain for commitment to the formation of the cortex. This is pretty cool stuff—genes that define how much brain tissue we have are likely to be important in human evolution. As I mentioned then, though, there is much more to building a good brain than raw bulk.
Now, in a recent article in Science, Piao et al. (2004) have identified another gene important in building brains, GPR56, which plays a role in organizing the distribution of cells within the cortex.
Continue reading "A very groovy brain gene" (on Pharyngula)