Upon sequencing the human genome, scientists were surprised to find that it is composed of about 8% viral sequence. These fossils are relics of ancient primate infections where retroviruses incorporated into the chromosome and became part of the human lineage. While these viral elements have contributed positively to speciation and development of specific human traits, they also have the capacity to become pathogenic. Dr. Advinda Nath is the Clinical Director of the National Institute of Neurological Disorders and Stroke. He joins Talking Biotech to share his experiences, knowledge and predictions in this exciting, emerging area of research.