Why was sex born?

2003/01/28 Roa Zubia, Guillermo - Elhuyar Zientzia

• Biologia
• Genetika

Scientists have been wondering for a long time. Life arose without sex; the 'first' living were microorganisms and were reproduced by processes such as folding, such as current microorganisms. But from an evolutionary moment, several living beings developed a sexual reproduction, that is, they exchanged genes with another of the same species to reproduce. With some genes from his father and others from his mother, the child becomes medium.

The truth is that it does not mean that genes are “chosen”. But the child has all the genes of his father and mother, so we have two copies of each chromosome. But in a very complex process, the child blocks some genes from his father and others from his mother to use the 'unique' group.

What advantage does it have? It is not very clear, but there are several hypotheses. One of them affirms that sex contributes to evolution. In short, if we take the best genes of each parent, the child will have better genetic characteristics than their parents. But to do this, the father and mother must have different genes, that is, have positive mutations and mutations.

To confirm this hypothesis, N. The British biologist Cognrave analyses an intermediate case in which he experiments with the alga Chlamydomonas reinhardtii, capable of experiencing both sexual and asexual reproduction. It has reproduced some algae asexually and others sexually, comparing the increases of both groups after the birth of many generations.

The result is clear: sexual reproduction increases the advantage of adaptation in cases of beneficial mutations. But beneficial mutations have to be necessarily, that is, the mutations that help in the adaptation process have the advantage. That is the driving force of evolution.

And when are beneficial mutations produced? The answer is simple: in nature there are beneficial mutations in cases of very large populations. In these populations all types of mutations will exist, both beneficial and harmful; evolution, of course, is used of the benefits to advance.