When humans and Neanderthals split into two species, the HPV virus evolved into different strains alongside them. Neanderthals and Denisovans carried a strain known as HPV16A. Early humans carried HPV16 B, C, and D. When humans migrated out of Africa around 60,000 years ago, they left those strains of HPV16 behind. But once they reached Europe and Asia, they encountered Neanderthals and their versions of the virus. They had sex, and that’s how humans acquired HPV16A.