““It is encrusted with history. Embedded within it are peculiar fragments of DNA-some derived from ancient viruses-that were inserted into the genome in the distant past and have been carried passively for millennia since then. Some of these fragments were once capable of actively "jumping" between genes and organisms, but they have now been largely inactivated and silenced. Like decommissioned traveling salesmen, these pieces are permanently tethered to our genome, unable to move or get out. These fragments are vastly more common than genes, resulting in yet another major idiosyncrasy of our genome: much of the human genome is not particularly human.””
