Genome and Epigenome

This chapter focuses on the role that genes play in the formation of human consciousness. While the genome has generally been defined as the sum of the genes in an organism, the more we study real genomes, the more we realise that viewing them in this way is a major oversimplification of their true complexity. Perhaps the most surprising outcome of the Human Genome Project was the realization that genes only represent a small fraction of the total DNA sequence. More recently, evidence has been accumulating to show that a significant proportion of the ‘non-coding’ DNA plays key roles in gene regulation—that is, determining which genes get switched on or off and when. In addition, instead of DNA being seen as the sole controller of cellular function, there is now growing recognition that RNA also plays a key role. Meanwhile, the new science of ‘epigenetics’ is revealing that the DNA ‘recipe’ for each organism appears far more responsive to the environment than previously thought, both to changes in the cellular environment, and those outside the organism itself. These new ways of looking at the genome have important implications for the understanding of how the human brain works, and of some of the factors that might make it unique compared to those of other species.