The Sexy Son Hypothesis: Explaining Sexual Selection
What leads a female to select one male among so many? Since Richard Dawkins talked about the selfish gene, several evolutionary scientists have tried to explain how females choose their partners in most social species.
One of the proposed theories is the sexy son hypothesis, which leaves almost no one indifferent with its more than striking name. Let’s see how he explains the process of reproductive selection and how it relates to evolution.
The sexy son hypothesis is one of the best-known evolutionary theories, especially because of its particular name. Although its origins date back to Richard Fisher in 1930, as it is formulated today we owe it to Patrick J. Weatherhead and Raleigh J. Robertson from Queen University, who clarified their postulates in 1979.
This hypothesis states that the selection of a potential reproductive partner by the female takes into account how attractive the children that arise from reproducing with one male or another will be. Thus, if the male children are attractive, when they grow up, they will be chosen by other females, which will cause the genes of the first female to be passed from generation to generation.
Within the theoretical framework of the sexy son hypothesis, more importance is given to an indirect factor, such as the aesthetic beauty of the potential partner, rather than more direct aspects such as their territorial dominance, physical strength or longevity. The female cares more about having many offspring than having children and grandchildren who are advantaged in terms of strength.
The female chooses, the species evolves
Since evolutionary biology was formulated, the idea has been defended that one of the fundamental factors in the survival and evolution of a species is how its females select the most desirable males.
In relation to this, Richard Dawkins, in his famous book The selfish gene (1976) already defended the idea that in animal species females choose males with the best genes. Males compete with each other so that many females select them, and The females choose one of them, the one that is best, to have children almost as desirable as their father.
Related to the sexy son hypothesis, if females select physically attractive males, then their offspring will be physically attractive as well. This will mean that their children will also be chosen by other females once they reach adulthood and, in turn, you will ensure having several grandchildren, causing your genetic load to survive and reproduce.
The sexual conflict
As we were already saying, females try to choose the best male while males want to reproduce with the maximum number of females possible. That is, females go for quality while males go for quantity.
Since males are not the ones who, in most species, have to give birth to their children, They can fertilize several females in a short period of time, having many offspring of highly variable genetic quality. Some of these children will not reach adulthood, but since there are many of them, there will always be the possibility that several of them will manage to reproduce, and thus pass on the male genes to the next generation.
On the other hand, females, also in most mammalian and social species, can only have one or two children at a time. It is for this reason that they choose to look for the male with the best characteristics and, within the hypothesis of the sexy son, the one who is more physically attractive. Your reproductive success depends directly on how attractive your male child becomes. If it does not attract other females, the mother’s genetic load will not be passed on to the next generation.
It is for this reason that we can understand that the sexual conflict between females and between males is different. The males compete to ensure that only one is the one who either has the right to reproduce or, in the most violent species, is the one who manages to survive and have intercourse with the females in the group.
For females, however, their competition is different, if there is any. They may have to fight to make sure the males notice them, although since most of them tend to go for the maximum amount, it is quite unlikely that they will forget to copulate with any of them.
Related to the sexy son hypothesis we have the theory of good genes, which is directly related to the fact that females select the best males, but without physical beauty being the only factor taken into account. Since they can often only have one or two children in a short period of time, females prefer that the few children they do have have good characteristics, which give them evolutionary advantages.
The theory of good genes, especially explained in the case of polyandry, proposes that females who find better males sleep with new ones to ensure that the eggs or eggs they have are fertilized with the sperm of the better quality male. .
The sexy son hypothesis and the good genes theory are related. As with good genes, the sexy son hypothesis assumes the existence of indirect genetic benefits that are capable of compensating for any directly observable reproductive traits, such as physical strength and parental care, for reproductive success.
The main difference between the good genes theory and the sexy son hypothesis is that the sexy son hypothesis assumes that this indirect factor is due to wondering how attractive the children will be based on sleeping with a certain male. On the other hand, in the theory of good genes Reproductive success is taken into account based on the survival of individuals for possessing advantageous characteristics for the environment or context in which they are found.
Sexy son hypothesis in humans
The sexy son hypothesis has been extrapolated to reproductive success in the human species. Research suggests that during the most fertile period of the menstrual cycle, women tend to be more attracted to men with traditionally masculine traits, especially being physically attractive and with traits attributable to having been exposed to higher levels of testosterone during fetal development.
On the other hand, when the menstrual cycle has subsided and women are less fertile, they tend to be attracted to men with more feminine facial features. It should be said that the studies that have reached these conclusions are quite criticizable, and these statements continue to be discussed.
According to research carried out by Oakland University, published in the Journal of Personality and Individual Differencesit was seen that the more attractive the man she copulates with is, the woman tends to have more orgasms, something that at first might seem obvious.
The fact of having several orgasms when sleeping with an attractive someone can be related to the sexy son hypothesis. Women are much more receptive to an attractive partner which will mean that, if you have children with her, these offspring will be equally selectable and, in turn, guarantee the survival of the woman’s genes.
It has also been seen that the possibility of a female reaching orgasm does not depend only on her subjective judgment of how attractive the partner she is having sexual relations with is, but also on how attractive the man is seen by the females in the area. .
And why not the sexy daughter hypothesis?
Up to this point, the sexy son hypothesis has been made from the male line of reproduction. By this we mean that, based on what this hypothesis postulates, the idea of having sexual relations with the most attractive man is to have sons who are also attractive and that, upon reaching adulthood, they manage to sleep with a high number. of women. However, little has been said about having sexy daughters.
Are females also recipients of those genes that would make them desirable like their brothers, the sexy sons? Is it important that females are attractive to males, if they also copulate with any of them?
According to doctors Raj Persaud and Peter Bruggen, and taking into account what we have commented previously in this article, Men, or males in most species, tend to care more about quantity than quality being much less selective when choosing a partner than compared to women or females.
That is why the influence of the female genetic load seems to be less decisive for males and, therefore, it does not matter how attractive the female is to them.
