A new study by Brazilian researchers goes into more detail as to why people are more likely to choose a mate whose genetic makeup is different from their own.
Researchers at the University of Parana, Brazil, studied 90 married couples' DNA and compared them to 152 randomly-generated control couples, EurekAlert explains. They looked for differences in couples' major histocompatibility complex (MHC), a genetic region found in most vertebrates that is related to the immune system. After comparing the couples MHC dissimilarities, scientists found that there were greater differences in the real couples than the virtual couples. "If MHC genes did not influence mate selection," said Professor Maria da Graca Bicalho, "we would have expected to see similar results from both sets of couples. But we found that the real partners had significantly more MHC dissimilarities than we could have expected to find simply by chance."
Other studies have shown that in humans and other vertebrates females prefer mates with dissimilar MHC. The genetic region is known to influence mating selection by creating a preference for certain body odors, like those found in sweat. Other research suggests that face structure may be influenced by MHC as well.
Scientists believe their findings, which were presented yesterday at the European Society of Human Genetics, reveal an evolutionary strategy to produce healthy offspring. According to the Telegraph people with more MHC variations in their immune system can recognize and cope with infections more easily. It may also be related to the evolutionary impulse to avoid incest. Previous studies have shown that couples with similar MHC genes had longer intervals between births, which may mean that they suffered undetected early miscarriages.
Professor Bicalho said that while people like to think that they chose their partner based on their similarities, "our research has shown clearly that it is differences that make for successful reproduction, and that the subconscious drive to have healthy children is important when choosing a mate."
Another scientist who conducted similar research on human leukocyte antigens, which also influence the immune system, turned her findings into a dating service that matches people based on their DNA. The Times of London reports that last fall Croatian geneticist Dr. Tamara Brown created GenePartner, a dating service that matches couples by analyzing their DNA samples. Brown says that people can't be matched solely on their genetic compatibility, but a good biological match means a greater likelihood of "forming an enduring and successful relationship; having a satisfying sex life; higher fertility rates and healthier children."
Opposites Attract — How Genetics Influences Humans To Choose Their Mates [EurekAlert]
Sexual Chemistry Found In Genes Causes 'Opposites To Attract' [The Telegraph]
DNA Dating: Has Science Unlocked The Secret Of A Perfect Match? [The Times of London]