While we may share ‘99% of our genes’ with chimps, some cutting edge research has shown that when it comes to evolution, taking the stance of pure genetic determinism may just make a monkey out of you. The gene bringing today’s lesson? CNTNAP2, one of nature’s largest, with a role in human-specific language abilities and neurodevelopmental disorders. In fact, this beast of a gene has just shown how epigenetic changes could accelerate the evolution of the human brain.

Thomas Haaf and scientists at the Julius Maximilian University in Germany hypothesized that epigenetic rather than genetic changes have accelerated the evolution of the human brain, and they’ve got the results to show it. The resarchers compared DNA methylation patterns in the brain (cortex) between humans and chimps, but rather than using a genome-wide approach, they focused in at “ultra-high resolution” with some MeDIP tiling arrays for CNTNAP2 orthologs and supporting sequences. Here’s what evolved:

Using a custom algorithm, more than half of the target region was aligned and analyzed across both species.

About 1/5th of the analyzed sequence showed significant methylation differences between human and chimp brains.

The “most striking interspecies difference”, revealed by bisulfite pyrosequencing, was that chimps have 31% more methylation in a region previously associated with autism spectrum disorders and genomic imprinting.

qPCR showed higher expression of certain transcript variants in the human brain. However, those transcripts did not show a skewed allelic expression, signalling that the gene may not be imprinted in the adult human brain, as previously believed.

The study uncovered numerous DNA methylation changes in a language gene after the evolutionary human-chimpanzee split, suggesting that fine tuned epigenetic regulation of CNTNAP2 was essential for the evolution of human-specific language and communication traits.

Go and make a monkey out of yourself over at Epigenetics, January 2014