It has been pointed out that the primary molecular mechanisms underlying genome evolution are 1) single nucleotide polymorphisms, 2) gene/segmental duplications, and 3) genome rearrangement. In addition, a “less-is-more” hypothesis has been proposed that argues loss of genetic material may also be a source of evolutionary change. Given these factors, what are we learning about their respective roles now that we can compare multiple primate genome sequences?
As we have pointed out repeatedly in this blog, the study of genetic influence on the brain is going to change our understanding of what a human is, how and why our thoughts are formed (and restricted) the way they are. This review surely puts the finger on the pulse and notes:
One of the most important findings to emerge from the latest human and primate genome-wide studies is that a fundamental assumption underlying this model has changed: the interspecies genomic changes are numerous and diverse, and, as a result, there appear to be many additional types of genomic mechanisms and features that could also be important to the evolution of lineage-specific traits. Given this new perspective, we now know that the degree of difference between our genome and that of the chimp depends on where, and how comprehensively, we look. The multitude of genomic differences that we now know exists should provide an abundance of fertile genomic ground from which important lineage-specific phenotypes, such as enhanced cognition, could have emerged.
Here is the abstract:
The jewels of our genome: the search for the genomic changes underlying the evolutionary unique capacities of the human brain
James M. Sikela
The recent publication of the initial sequence and analysis of the chimp genome allows us, for the first time, to compare our genome with that of our closest living evolutionary relative. With more primate genome sequences being pursued, and with other genome-wide, cross-species comparative techniques emerging, we are entering an era in which we will be able to carry out genomic comparisons of unprecedented scope and detail. These studies should yield a bounty of new insights about the genes and genomic features that are unique to our species as well as those that are unique to other primate lineages, and may begin to causally link some of these to lineage-specific phenotypic characteristics. The most intriguing potential of these new approaches will be in the area of evolutionary neurogenomics and in the possibility that the key human lineage–specific (HLS) genomic changes that underlie the evolution of the human brain will be identified. Such new knowledge should provide fresh insights into neuronal development and higher cognitive function and dysfunction, and may possibly uncover biological mechanisms for information storage, analysis, and retrieval never previously seen.
John Hawks has a very good discussion about this article.