A popular theory explaining the need for sexual intercourse has been refuted by Canadian scientists using mathematical modeling, the BBC reports.
Evolutionary biologists still haven't reached a consensus on why living organisms have so much sex. Asexual reproduction has many advantages: organisms that reproduce this way expend much less energy, produce more offspring, and are also less likely to contract sexually transmitted infections.
On the other hand, sexual reproduction is believed to play a significant role in evolution, and this is the basis for the so-called “Red Queen hypothesis,” one of the most popular among evolutionary biologists. The hypothesis takes its name from a character in Lewis Carroll's “Through the Looking Glass”: it was the Red Queen who advised Alice to run as fast as possible to stay in the same place. According to the Red Queen hypothesis, gene exchange during sexual reproduction allows organisms to better defend themselves against various parasites. Since parasites constantly improve (for example, viruses mutate), animals and humans must also constantly “diversify” their genomes to protect themselves from them.
However, according to Sarah Otto of the University of British Columbia (Vancouver, Canada), this theory fails to explain why humans and animals have so much sex. According to a mathematical model developed by Sarah Otto and her colleague Scott Nuismer, to protect themselves from parasites, living organisms would only need to have sex occasionally and primarily reproduce in “non-sexual” ways.
“A little sex is enough to generate the gene combinations needed for defense. But a lot of sex simply destroys these combinations. Since we, like many other organisms, have sex far more often than necessary, it's worth looking for a more advanced explanation for sex than the Red Queen hypothesis,” Dr. Otto believes.