Discover traces the ancestry of a persistent sexually transmitted disease, and finds that the human papillomavirus (HPV) that causes cervical cancer probably came from modern humans having sex with Neanderthals:
Although over 200 types of the virus exist, the National Cancer Institute indicates just two — HPV16 and HPV18 — account for about 70 percent of all cervical cancers. HPV16 infection can also lead to anal cancer and cancers that develop in the throat, at the base of the tongue and the tonsils.
“There is no more carcinogenic agent that causes cancer in humans than HPV, especially HPV16,” said Robert Burk, who led the new research.
In research published last year, Burk and colleagues analyzed the genetic sequences of HPV16 viruses from thousands of individuals and found that few women shared an identical form of the virus. It’s an indication that the virus has a knotty evolutionary past, and understanding might help shed light on why it can go on to cause cancer in some cases.
To find out how the highly pathogenic HPV16 type of the virus evolved, the team then compared more than 200 complete HPV16 virus genomes and over 3,500 partial sequences isolated from around the world. When the researchers analyzed the virus’ evolutionary tree, they discovered that an ancient version of the virus split off onto its own evolutionary trajectory at about the same time modern humans separated from Neanderthals around 618,000 years ago. This version later evolved into four sub-types of HPV16 in Eurasian populations, the team reports today in the journal PLOS Pathogens. The timing coincides with a split in Neanderthal populations that spread through Eurasia around 100 thousand years ago.