^This is a story about mutant children, or are they evolving humans?
in "A Short Biological Primer" at the end of the book, Bear discusses viruses and DNA:
It is possible that viruses originally came from segments of DNA within cells that can move around, both inside and between choromosomes. Viruses are essentially roving segments of genetic material that have learned how to "put on spacesuits" and leave the cell. (p479)