

Porn makes sperm better swimmers ABC Science Online







Pornography involving a woman alone or multiple women doesn't have the same effect.



Evolutionary biologist Professor Leigh Simmons of the



This occurs when semen quality increases according to the perceived risk of another male fertilising a female.



"Males ejaculate more sperm, or sperm of better quality, when the risk of sperm competition [the probability that a female will mate with more than one male] is high," Simmons writes in the journal



Simmons says his research now shows that just looking at an image of another man in action is enough to register as a case of sperm competition, causing a compensatory adjustment in the viewer's semen.



"Our data show that image content can have an impact on men's semen quality," he says.



"We show that ... human males viewing images depicting sperm competition had a higher percentage of motile [efficiently moving] sperm in their ejaculates."



Putting it to the test



Simmons says previous Australian research sparked his interest in exploring this twist on sexual selection.



These studies show sperm counts are higher if men are given pornographic material before in-vitro fertilisation (IVF) procedures.



Psychological studies also show that when men look at pornography depicting more than one person they prefer to see at least one more man.



"It seems that men like to see other men in these images," he says.



To test the theory, 52 heterosexual men aged 18 to 35 were shown two images over two separate days. One showed three women, the other a woman with two men.



Masturbatory samples of their sperm were then tested for the number of sperm per millilitre of ejaculate and sperm motility, or ability to swim, which is associated with the ability to fertilise an egg.



"We tested the evolutionary hypothesis that the men who viewed those sort of mixed sex images should have a higher semen quality if it was stimulating some innate evolved response to competition," he says.



"We found men viewing images containing both men and women had higher sperm motility in masturbatory ejaculate compared to men who were viewing images of just women alone."



It was not clear how pornography affected sperm count, he says.



A new fertility aid?



Simmons says the study needs replicating and it's too early to say whether looking at images of group sex involving men could be a useful tool in aiding fertility.



Other lifestyle factors are involved in fertility, he says, such as avoiding alcohol and drugs.



Dr Kylie de Boer, embryology director at Sydney IVF, says men involved in assisted reproduction are routinely provided with "light pornography" to assist them in producing semen.



But she doubts that viewing pornography, of any kind, would have a major impact on a man's ability to fertilise an egg.



"It's to help them with their arousal in what can be a stressful situation," she says.



"The man's general health would perhaps be a more important factor in what [the quality of his sperm] is like." Looking at pornographic images of men and women together can increase the quality of a man's sperm, a new study suggests.Pornography involving a woman alone or multiple women doesn't have the same effect.Evolutionary biologist Professor Leigh Simmons of the University of Western Australia says the effect is based on an evolutionary process observed in animals known as sperm competition.This occurs when semen quality increases according to the perceived risk of another male fertilising a female."Males ejaculate more sperm, or sperm of better quality, when the risk of sperm competition [the probability that a female will mate with more than one male] is high," Simmons writes in the journal Biology Letters today.Simmons says his research now shows that just looking at an image of another man in action is enough to register as a case of sperm competition, causing a compensatory adjustment in the viewer's semen."Our data show that image content can have an impact on men's semen quality," he says."We show that ... human males viewing images depicting sperm competition had a higher percentage of motile [efficiently moving] sperm in their ejaculates."Simmons says previous Australian research sparked his interest in exploring this twist on sexual selection.These studies show sperm counts are higher if men are given pornographic material before in-vitro fertilisation (IVF) procedures.Psychological studies also show that when men look at pornography depicting more than one person they prefer to see at least one more man."It seems that men like to see other men in these images," he says.To test the theory, 52 heterosexual men aged 18 to 35 were shown two images over two separate days. One showed three women, the other a woman with two men.Masturbatory samples of their sperm were then tested for the number of sperm per millilitre of ejaculate and sperm motility, or ability to swim, which is associated with the ability to fertilise an egg."We tested the evolutionary hypothesis that the men who viewed those sort of mixed sex images should have a higher semen quality if it was stimulating some innate evolved response to competition," he says."We found men viewing images containing both men and women had higher sperm motility in masturbatory ejaculate compared to men who were viewing images of just women alone."It was not clear how pornography affected sperm count, he says.Simmons says the study needs replicating and it's too early to say whether looking at images of group sex involving men could be a useful tool in aiding fertility.Other lifestyle factors are involved in fertility, he says, such as avoiding alcohol and drugs.Dr Kylie de Boer, embryology director at Sydney IVF, says men involved in assisted reproduction are routinely provided with "light pornography" to assist them in producing semen.But she doubts that viewing pornography, of any kind, would have a major impact on a man's ability to fertilise an egg."It's to help them with their arousal in what can be a stressful situation," she says."The man's general health would perhaps be a more important factor in what [the quality of his sperm] is like."



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