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[The following is an exact transcript of this podcast.]
If you paid attention during high school biology, you probably remember that girls are born with all the eggs they’ll ever have, whereas guys are churning out sperm pretty much all the time. Now, several new studies, in animals from mice to worms, suggest that sperm supply is closely tied to demand. And that how much sperm an individual male makes may influence whether females seek multiple mates.
One study, published by the Royal Society, showed that mice make more sperm when they compete with romantic rivals. That finding is the first demonstration that a male mammal can adjust his sperm output depending on social circumstance, in this case, making more sperm to better the odds that he’ll come out on top in a reproductive show-down.
Worms take the whole supply-and-demand thing to the extreme. According to a study published in the journal Current Biology, when females aren’t around, one type of nematode worm doesn’t make any sperm at all.
That kind of abstinence may work for a nematode, but for other species being stingy with sperm may backfire. According to a paper published in Science, when male fruit flies skimp on the sperm count, females simply mate with more partners. Something male flies might keep in mind if they want to avoid heartbreak this holiday season.
—Karen Hopkin
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4 Comments
Add CommentMost of the women I've known over the years have had multiple partners too, but they way they talk about it, its because of what they see on television. I wonder how fruit flies would fare with prolonged, repeated exposure to simulated complex social melodrama and soft-lens softcore porn.
Reply | Report Abuse | Link to thisI also wonder which came first, the multiple sex partners, or the discovery that one of their sperm counts is lower than the others...
hm.
If your going to report on science than get it right! You may have been taught in school that a woman is born with all the eggs she will ever have! But it was reported in science news that this is wrong, there is strong evidence that women produce new eggs threw menopause, but that these eggs decrease in number and quality as they age. If your going to report on science than please try to stay currant or find something else to report on there is enough miss information in science already!!!
Reply | Report Abuse | Link to thisIt appears that oddy is referring to a study from 2005 that indicates that it may be possible that women do produce fresh eggs--although many experts dispute those findings:
Reply | Report Abuse | Link to thishttp://www.fertilityneighborhood.com/content/in_the_news/archive_1259.aspx
Although we always thank our listeners and readers for additional information or corrections, we must wonder why the updates often seemed to be delivered with such vitriole and passion that the commentator can not even spare the time to spell check the diatribe.
Perhaps oddy doesn't have a wife or dog to kick when he gets home. We readers here at Scientific American understand WHY!
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