Why most higher living beings practice sexual reproduction is still not fully understood scientifically. Austrian-born biologist Elvira Hörandl and her Dutch colleague Dave Speijer have now published a new thesis in the journal "Proceedings of the Royal Society B." So sex could originally have been a measure against genotype damage.
The actual reason for the evolutionary triumph of this complex and thus also error-prone biological process is often a research question. The biologist from the University of Göttingen and her colleague from the University of Amsterdam set about 2 billion in their investigation. Around this time, the first creatures with nucleus (eukaryotes) were formed, as the University of Göttingen announced in a press release.
At that time - so scientists suspect - two unicellular organisms united. One of them became the mitochondrion, which since then has been responsible for the energy supply in the cell. It does so by injecting oxygen into the cellular community. Thus, the two unicellular organisms united in symbiosis could draw on much more energy, but the oxygen radicals that entered the cell were a source of danger because they could damage the genetic material.
Especially in stressful situations, the original strategies for the protection of DNA were often insufficient, according to the theory of Hörandl and Speijer. Therefore, meiosis (reduction and recombination division), in which the genetic material of two cells and cell nuclei is mixed, has already developed in the first eukaryotes as an efficient DNA repair mechanism. "Sex is therefore a physiological necessity, as a result of an oxygen-based metabolism in all higher organisms," said Hörandl.
In complex organisms, sex then took on its role as a process of genetic renewal, with which mutations can also be specifically eliminated. Hörandl sees her hypothesis supported by "numerous genomic, karyological and biochemical investigations in recent years"