“We know that our bodies are absolutely teeming with microbes. In the average healthy human, bacterial cells outnumber our own cells 10 to 1. And let’s not forget about viruses; some studies have suggested that the number of viral particles in our body is greater than the number of human and bacterial cells combined. But what about our genomes? It turns out that our DNA, too, is less human than we thought.
According to a new study, humans—and a wide variety of other animals—possess tens, if not hundreds of “foreign” genes that have been passed on from single-celled organisms, such as bacteria. What’s more, these genes play active roles in the body, such as contributing to metabolism, and this process of gene acquisition could still be occurring, at least in some lineages. According to the authors, these findings suggest that this gene transfer could have played a previously underappreciated role in biochemical diversification during the evolution of animals. The study has been published in Genome Biology.”