A team of researchers at the Weizmann Institute of Sciences in Israel has discovered that thousands of genes are expressed – a process that gives rise to proteins – differently in men and women. In a study published in the journal BMC Biology , Shmuel Pietrokovski and Moran Gershoni, two experts from the Department of Molecular Genetics of the aforementioned institution, point out that certain harmful mutations in these genes end up accumulating in the population and that both sexes follow what could be considered a separate but interconnected evolutionary path .
In previous work, these scientists already showed that, for example, mutations in very specific genes related to sperm formation and negatively affecting fertility have not been suppressed by natural selection and persist precisely because they are expressed only in the men . Thus, a variation that is a problem for half the population is transmitted from one generation to another by the other half.
Now Pietrokovski and Gershoni have identified6,500 genes that show different activity in at least one tissue based on sex. To do this, they have studied 20,000 protein-coding genes registered by the GTEX (Genotype Tissue Expression) project, the objective of which is to map the expression and genetic regulation of our species. These experts point out that, for example, some genes related to the growth of body hair are expressed much more in men’s skin than in women’s; something similar happens with those that affect the development of muscles, while those that intervene in the accumulation of fat tend to be greater in them. Similarly, they found some that are only expressed in the left ventricle of the female heart; one of them is related to the acquisition of calcium and could play a cardioprotective role until menopause.Another, present mainly in women, seems to be involved in the prevention of Parkinson’s.
In their conclusions, the scientists point out that the more specific a gene appears to be a certain sex, the less pressure natural selection exerts on it. In the case of men, this is even less. As indicated in a statement, since the 30s of the last century there has been speculation with a hypothesis that could explain this issue: in many species, their survival depends on the existence of more viable females than males, since the former can only produce a limited number of offspring while, in theory, males can be parents of many more. Thus,the natural selection that Pietrokovski and Gershoni refer to could be, so to speak, looser with genes that in certain circumstances can only harm males.
Image: Weizmann Institute of Sciences
