In the instruction book of life, which is the human genome, there are some mysterious particles that tend to remain silent, without making noise or having any function, for thousands and thousands of years. They are a species of ancestral viruses, remnants of ancient pandemics, that were embedded in the DNA of germ cells (eggs or sperm), and were passed from generation to generation. Until today. The 8% of the human genome is made up of those disturbing viral relics about which not much is still known. The little that has been discovered, for now, is that, when they are resurrected and activated, they can end up playing a key role in health or disease: for example, sequences of these very ancient viruses have been described that can help develop placenta or a encourage tumors and neurodegenerative diseases.
