One of the great mysteries of biology is why sexual reproduction (SR exists in such a widespread fashion or even why it exists at all. Evolution is the business of keeping the organisms with the characteristics that better fit the environment (have the so called “higher fitness”) and SR does not seem to be an advantageous process. In fact, it not only requires much more energy that asexual reproduction (ASR), but it is also a much less efficient way of producing new individuals and, consequently, of passing on genes to the next generation (as in an ASR population all individuals, and not only females, are able to bear young). Thus, to be maintained as the main form of reproduction, sex must have some crucial unknown evolutionary advantage. And now, in a paper about to be published on the 2^nd of March in the journal Nature¹, scientists claim to have found new evidence supporting the idea that this evolutionary advantage is an enhanced capacity to eliminate harmful mutations. Purging these mutations leads to “cleaner” genomes, increasing the fitness of the population that use SR, and assuring its preservation throughout evolution.

*  "This article is the result of a project for the divulgation of portuguese science" http://www.cienciahoje.pt/1455