Men Need Competition For Evolution, Sexual Selection

by Monica Joshi

With all the new reproductive technology, it seems like an all-female population would be a far more effective route to reproduce and to produce as many offspring as possible. Sexual reproduction is both inefficient and costly and yet many multicellular species continue to reproduce in this fashion. So we have to ask, why do we need men?

Researchers from the University of East Anglia (UAE) believe that they may have an answer: sexual selection plays an important role in improving population health and aids in evolution by protecting us against extinction. Sexual selection is a processes whereby males compete with each other for a chance to reproduce, while females choose the male with whom they want to reproduce.

Lead researcher, Professor Matt Gage, said in a statement that:

"Almost all multicellular species on earth reproduce using sex, but its existence isn't easy to explain because sex carries big burdens, the most obvious of which is that only half of your offspring—daughters—will actually produce offspring. Why should any species waste all that effort on sons?”

The study published in the journal Nature, followed humble flour beetles to help understand why most multicellular organisms need sexual reproduction. Researchers studied 50 generations of beetles over a ten year period to test the impact of sexual selection on evolution.

For the study, the biologists created two separate populations of these promiscuous, yet sturdy beetles controlling only one difference between the two of them. They controlled the intensity of sexual selection and the ratio of males to females during each stage of the reproductive cycle. In one of the populations, 90 males were competing for 10 females, while in the other, the pairing was monogamous.

When the population was devoid of sexual selection, the population's health declined rapidly and the bugs were wiped out by the 10th generation.

Gage claimed that as a conclusion of the study, it seemed to be clear that:

"To be good at out-competing rivals and attracting partners in the struggle to reproduce, an individual has to be good at most things, so sexual selection provides an important and effective filter to maintain and improve population genetic health. Our findings provide direct support for the idea that sex persists as a dominant mode of reproduction because it allows sexual selection to provide these important genetic benefits."

Some of the beetles even survived after 20 inbred generations, where a brother mated with a sister in each of the generations.

Sexual selection, therefore, plays a crucial role in sifting out harmful genetic mutations. Despite the beetles' inbreeding, the study found that the populations that were strongly influenced by sexual selection were able to maintain population health and avoid extinction. Seems like men are not only a desire, but also a necessity when wanting to evolve as a species.