Feminists have “debated” it for decades, but scientists have “finally” got to the bottom of “why men still exist.”
Since in many species, sperm is males’ only contribution to reproduction, biologists have long “puzzled” about why “evolutionary” selection, known for its “ruthless” efficiency, allows them to exist.
Now Scientists have an explanation: “Males are required for a process known as ‘sexual selection’ which helps species to ward off disease, keeps populations healthy, genetically diverse and avoids extinction. “
A system where all “offspring’s” are produced without sex — “as in all-female asexual populations” — would be far more efficient at “reproducing” greater numbers of offspring, the scientists said.
In a research published in the journal Nature, they found that sexual selection, in which males “compete” to be chosen by females for “reproduction,” improves the “gene” pool and boosts “population” health, helping explain why “males” are important.
An absence of selection — “when there is no sex, or no need to compete for it” — leaves populations genetically “weaker,” making them more vulnerable to “dying” out.
“Competition among males for reproduction provides a really important benefit, because it improves the genetic health of populations,” said professor Matt Gage, who led the work at Britain’s University of East Anglia.
“Sexual selection achieves this by acting as a filter to remove harmful genetic mutations, helping populations to flourish and avoid extinction in the long-term.”
“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,” said lead researcher Prof Matt Gage, from the University of East Anglia School of Biological Sciences.
“Why should any species waste all that effort on sons?
“It makes far more sense in evolutionary terms to have an all-female asexual population which creates daughters who can reproduce rather than sons who cannot, such as the Mexican whip tail lizard.”
Charles Darwin first suggested the idea of “sexual selection” in which males compete for reproduction and females choose. It is why the males are often far more brightly “colored” than females, and partake in elaborate “courtship” rituals.
Darwin proposed that “sexual selection” is responsible for many of the features “unique” to one sex, acting as “ornaments” that attract the attention of females. Darwin concluded that “color” differences between sexes result largely from female “preference” for bright colors in males.
Extensive field studies have shown that females use the “brightness” of a male’s color as an important indicator of his “health and vitality,” and that “artificially” brightened males were much preferred by females, but that “naturally” brighter males were better at “providing” food.
But until now nobody “realized” how great a role it “played” in the health and success of societies.
In their study, Gage’s team observed a colony of “Tribolium” flour beetles over 10 years under “controlled” laboratory conditions, where the only “difference” between populations was the “intensity” of sexual selection during each adult “reproductive” stage.
The strength of “sexual selection” ranged from intense competition — “where 90 males competed for only 10 females” — through to the complete “absence” of sexual selection, with “monogamous” pairings in which females had no “choice” and males no “competition.”
After seven years of “reproduction,” representing about 50 generations, the scientists found that populations where there had been “strong” sexual selection were fitter and more “resilient” to extinction in the face of inbreeding.
But populations with “weak or non-existent” sexual selection showed more rapid “declines” in health under inbreeding, and all went “extinct” by the tenth generation.
Prof Gage said: “These results show that sexual selection is important for population health and persistence, because it helps to purge negative and maintain positive genetic variation in a population.”
“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.”
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