Attractive males produce less sperm per encounter

Interestingly, the attractive men hold back some of the sperm for future partners as they intend to produce offspring with a range of women, reveals the study.

Bird study valid for humans too
The research was conducted at the University of Oxford and University College London (UCL). For the purpose of the study, the researchers mathematically modeled a variety of male ejaculation stratagem to figure out the best possible ‘sperm load’ per mating. The researchers also analyzed how this load would vary depending on mating patterns.

The research has been carried out on birds and chicken as of now, however experts opine that the same theory would hold water in case of humans as well.

UCL researcher Sam Tazzyman opined, "Human attractiveness is complicated and influenced by a number of factors including cultural preferences. Nonetheless, ejaculate size and sperm quality are likely to have been molded by similar forces, like attractiveness and the number of sexual partners, that are important in other species."

More partners, reduced value
Researchers opine that unattractive males, unlike attractive ones, know they are going to bed with fewer females. As a result, as and when they get a chance, they give it their best shot.

Tazzyman explained, "The more attractive a male is, the more females will be willing to mate with him, reducing the value of each mating to him. This means it is optimal for him to contribute fewer sperm per mating. Although this reduces fertility per mating, it maximises the number of offspring he sires overall.”

On the other hand, less attractive males manage fewer matings and therefore each one of it is significant to them. As a result, more sperm are allocated by them in each encounter.

“This leads to the rather paradoxical prediction that matings with attractive males may be less fertile than those with unattractive males," opined Tazzyman.

The study is due to be published in the journal American Naturalist in September.