The above link is to an article describing a discovery relating to how the human brain differs from the brains of other mammals and may shed light on how our brains have evolved to allow more complex thought. To quote the article: "Cell adhesion controls many aspects of brain development including growth and structure, and enables neurons to connect with other neurons and supportive proteins. Differences in the molecular connections of human neurons compared to the neurons of chimps, mice and other animals, could help explain why the human brain is capable of far more complex cognitive functions."
This discovery is related to DNA sequences that determine when genes are switched on or off. The effect of DNA is not just to determine the genes and hence the morphology of the organism. The same genes can generate different features in an organism depending on when it is allowed to work and when it is prevented from working. This could explain why humans and chimpanzees share 98 percent of the same genome, yet the end result is quite different. This provides a new avenue for evolution, one that does not change the genes but when they turn on and off. For more on this idea, see the next article.