https://www.livescience.com/61627-ancient-virus-brain.html

“Though it may sound surprising that bits of human genetic code come from viruses, it’s actually more common than you might think: A review published in Cell in 2016 found that between 40 and 80 percent of the human genome arrived from some archaic viral invasion. [Unraveling the Human Genome: 6 Molecular Milestones]”