World Feature

Why do men exist? Scientific study offers an explanation

19 May 2015 - 105   - 0

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 British scientists have an explanation: Males are required for a process known as "sexual selection" which helps species to ward off disease and avoid extinction. A system where all offspring are produced without sex -- as in all-female asexual populations -- would be far more efficient at reproducing greater numbers of offspring, the scientists said. But in research published in the journal Nature on Monday, they found that sexual selection, in which males compete to be chose 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 weaker genetically, 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 multi-cellular species reproduce using sex, but its existence is not easy to explain biologically, Gage said, because sex has big downsides -- including that only half of the offspring, the daughters, will produce offspring themselves. "Why should any species waste all that effort on sons?" he said. In their study, Gage's team evolved 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. [caption id="attachment_76155" align="alignnone" width="500"]A shop worker rests in the shade along the beach in Recife June 10, 2014. REUTERS/Brian Snyder A shop worker rests in the shade along the beach in Recife June 10, 2014. REUTERS/Brian Snyder[/caption]

  Comments - 0

  • Leave a comment



Top Stories

EC receives more than 1000 complaints on violence, law violations

The Election Commission (EC) has received more than 1000 complaints of election violence or law violations, nearly two weeks after announcing the f...

20 October 2019 - Views : 11

EC releases contact details to file complaints during run-up to presidential poll

19 October 2019

Education Ministry seeks Rs 2.5 billion from Treasury to resume stalled projects

19 October 2019

Gotabhaya pledges new political culture rid of corruption

19 October 2019

Features & Analysis

Special screening programme for breast cancer at Early Detection Centre in Narahenpita

October is designated as ‘Breast Cancer Awareness Month’, worldwide. Cancer ranks amongst the leading thr...

The Wolf is back! ‘Big Bad Wolf Book Sale’ to get underway from tomorrow

The wolf is here with books for us to devour! The highly anticipated ‘Big Bad Wolf Sale’ which is open to...

Toyota's latest Rav4, Corolla and HIACE hit the streets

Toyota Lanka (Pvt) Ltd, the sole authorized dealer for Toyota vehicles and spare parts in Sri Lanka recently launched...

English Lit Societies of Ladies and STC present LitCon

The English Literary Societies of Ladies' College and S.Thomas' College Mt.Lavinia proudly present LitCon ...