Sex is good for health as it does not accumulate harmful mutations, a new study has confirmed. Jesse Hollister, a former University of Toronto post-doctoral fellow, said that the findings have allowed them to understand why an enormous diversity of species around the world go through the laborious process of sexual reproduction.
For decades, evolutionary biologists found sexual reproduction to be a paradox. Mathematically, asexual reproduction seemed to make more sense. Each organism – not just half the population — could produce offspring, and all its genes were passed on, rather than the 50 percent from each parent in offspring from sexual unions.
Hollister said that new mutations occur naturally in every species from one generation to the next. When species reproduce sexually, their genes are separated, shuffled and recombined in various ways, so each offspring doesn't receive all of their parents' mutations in addition to the naturally occurring ones. In asexual reproduction, however, the species copies the existing genome as a whole, effectively cloning itself. Therefore, they pass on all the mutations that naturally accumulate from generation to generation.
Asexual reproduction leads to a buildup of deleterious mutations over time; it's called Muller's Ratchet and the species' average fitness is reduced and they are less able to compete in the ecological arena than sexual species, so they have an increased probability of extinction.