In the current era of microbiome research, us humans are already having to come to grips with the fact that ‘I’ is actually ‘we’. Instead of our bodies constituting a single life-form, we are each comprised of complex and diverse ecosystems of microbes that have a profound influence on our existence. Our health and wellbeing are not just determined by what our own cells do, but what our trillions of invisible inhabitants do, too. And the genetic blueprints that govern our biology are partly carried in those microbial inhabitants, as well as in our own cells.

But, as it happens, the DNA in our own cells isn’t solely ours, either. More than eight percent of the human genome is not human at all—it’s from viruses. And scientists are still digging up yet more viral code from human DNA that may well influence our lives. In a new study this week, researchers analyzed the genomes of more than 2,500 people and found 19 never-before-noticed segments of viral genetic code. Some of that viral DNA may have been traveling down human lineages for at least 670,000 years, the researchers reported in the Proceedings of the National Academy of Sciences. READ MORE