99 percent of the functional genes in the body are microbial. Researchers [are uncovering] how genes in this microbiome — exchange messages with genes inside human cells.
Most DNA, for example, was long considered junk — a netherworld of detritus that had no important role... [However] signals coming from both regions of the genome participate in the delicate balance between normal cellular behavior and [cancer] malignancy.
Some 90 percent of the protein-encoding cells in our body are microbes. We evolved with them in a symbiotic relationship, which raises the question of just who is occupying whom.
As I've previously described, this mechanism is also a possible engine of "directed evolution".