Why would a sterile male cricket mate with an infertile female? On the surface, this behaviour makes no sense: sex takes energy and effort, and there’s nothing in it for either of these partners. Neither one can foster the next generation.
Shelley Adamo from Dalhousie University has the answer. Her team have shown that one particular insect virus can sterilise crickets, but also change their behaviour so they continue to mate with each other. By doing so, they pass the virus on to uninfected hosts.And there's this from Richard Dawkins' The Selfish Gene:
One of the best-known segregation distorters is the so-called t gene in mice. When a mouse has two t genes it either dies young or is sterile. t is therefore said to be 'lethal' in the homozygous state. If a male mouse has only one t gene it will be a normal, healthy mouse except in one remarkable respect. If you examine such a male's sperms you will find that up to 95% of them contain the t gene, only 5% the normal allele. This is obviously a gross distortion of the 50% ratio we expect. Whenever, in a wild population, a t allele happens to arise by mutation, it immediately spreads like a brushfire... before long the whole local population is likely to be driven extinct. There is some evidence that wild populations of mice have, in the past, gone extinct through epidemics of t genes.Also, we have the explanation of the Bruce effect from the same tome - male mice secrete a chemical whose smell can cause female mice to abort her current pregnancy so the new male mouse can successfully mate with her. There is also the reverse Whitten effect: female mice synchronize menstrual cycles based on olfactory cues.
We already know that people infected with Toxoplasmosis gondii display measurably different mental behaviour compared to those who do not. T. gondii victims have six times the rate of automobile accidents as non-infected people. Given the love women traditionally have for cats, this may explain why women are stereotypically described as worse drivers than men. Men infected with the organism tend to engage in more risk-taking behaviour. Schizophrenics are twice as likely to be infected as the general population.
So, is it possible that some gene, bacteria or virus or combination is part of the reason so many people seem to have gone insane and begun embracing homosexuality, contraception and abortion in the last century?
I am certain no one has investigated possible links.
There could be a medical discovery waiting to be made!