Sex Benefits Humans Over Time with Disease Resistance

For decades, scientists have examined the genetic advantage of sexual reproduction versus asexual reproduction. Yet theories of this genetic advantage have never been proven in humans--until now. Researchers have found that humanity's predispositions to disease gradually decrease the more our genetic material mixes.

Generation after generation, the exchange of genetic material between humans causes our species to evolve little by little. Chromosomes from the mother and father recombine to create the chromosomes of their child. Yet parents' genomes don't mix together in a uniform way. Instead, chromosomes recombine frequently in some segments of the genome, while recombination is less frequent in others. These segments of low-frequency recombination will eventually recombine, but take many generations.

The researchers studied the sequenced genomes of hundreds of individuals. They found that the proportion of mutations associated with disease was significantly higher in low recombining segments known as "coldspots."

More specifically, the researchers found that the segments of the human genome that don't recombine often tend to carry a significantly greater proportion of the more disease-enabling genetic mutations. Until a chromosome recombination occurs, these segments accumulate more and more bad mutations. This means that as far as susceptibility to disease is concerned, our genetic material actually worsens before it gets better. Sexual reproduction, though, ensures that this recombination eventually happens.

"This discovery gives us a better understanding of how we, as humans, become more or less at risk of developing or contracting diseases," said Philip Awadalla, one of the researchers, in a news release.

The findings reveal a bit more about how sexual reproduction benefits humans. It turns out that it helps with resistance to disease over time. This is especially important for species hardiness and survival.

The findings are published in the journal Nature Genetics.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).