French scientists have put forward an unexpected hypothesis for the eviltion of sex, PLoS Biology reported.
According to the source, multicellular creatures refused asexual reproduction due to the spread of infectious forms of cancer.
Frederic Thomas from the University of Montpellier and his colleagues point to the Tasmanian Devil's Facial Tumor (DFTD), due to which this mammal species is included in the list of animals on the verge of extinction. A feature of DFTD is that tumor cells are transmitted directly from animal to animal. A similar disease significantly reduces the population of several species of mollusks in the Atlantic. In addition, as you know, dogs suffer from cancer, which is transmitted sexually.
Experts note the emergence of such a contagious cancer by a low level of genetic diversity among marsupial predators, mollusks and ancestors of dogs, which has become a favorable factor for cancer cells.
According to scientists, the easiest way to protect against cancer is reproduction through sexual contact, as a result of which offspring with a unique genome is born. This, in its turn, allows you to protect it from the invasion of infectious cancer cells. As a result, cancer can develop only due to mutations due to DNA damage.