"Semen has controlling power over female genes and behaviour" — so proclaimed a New Scientist headline on Wednesday, in an article about semen...in fruit flies.
That's only the latest in a decade of media coverage claiming that semen has a mysterious power over women's brains.
It all started in 2002, with one study published in the Archives of Sexual Behavior. The study, done by evolutionary psychologist Gordon Gallup and his colleagues at SUNY Albany, claimed to have found that semen has "antidepressant properties."
It was just one, extremely weak study (more on that later), and even the study's authors admitted in the paper that "our findings raise more questions than they answer." But its message just won't die.
In 2011, the editor-in-chief of Surgery News resigned amid controversy after writing an editorial suggesting readers give their partners semen instead of chocolates for Valentine's Day.
In 2012, seemingly out of nowhere, the Daily Mail ran an article that started with the sentence, "Oral sex is good for women's health and makes you feel happier," talking about the Gallup paper like it was new.
The hype around the study got so intense that the U.K.'s National Health Service told everybody to stop talking about it. "This study is full of holes — and extreme caution should be used when interpreting anything from it," the NHS wrote.
"Be a little cautious with this topic," Debra Lynne Herbenick, a sexual-health educator at the Kinsey Institute in Bloomington, Indiana, told BuzzFeed News by email. "Every time it hits a news cycle, some men use it in some pretty manipulative ways toward women."
Gallup, the author of the original study, also expressed frustration at how the media has covered it.
"I have to constantly remind people that just because semen may have antidepressant properties, it doesn't mean you should start having unprotected sex," he told BuzzFeed News by email. "If you throw away your condoms and contract an STD or develop and unwanted pregnancy, it could make you current depression seem like child's play as a consequence."
So what did the study claim, exactly?
Except...there's no plausible mechanism for how semen would affect a woman's brain.
Plus, this happy juice theory makes no evolutionary sense.
Pavol Prokop, a cultural anthropologist at the University of Trnava in Slovakia, doesn't think this theory makes any sense. (In fact, in 2002 he published a study replicating the Gallup study in 261 Slovak women, and got totally different results.)
If semen really did have antidepressant properties, Prokop told BuzzFeed News by email, then wouldn't the average woman be excessively promiscuous in order to obtain as much semen as she could handle? "This is, however, not true for majority of women," he said.
"I do not see any strong affinity of women with male ejaculates and could not find any reasonable evolutionary scenario which could support production of antidepressants by men."
But what about the study's findings?
Plus, the study didn't account for many, many possible confounding factors.
And there's plenty of research suggesting the study's conclusions are absolutely backwards.
There's one thing, though, that semen certainly can produce...
This story has been updated to include comments from Gallup.
Cat Ferguson is a writer based in Oakland, California. You can follow her on Twitter @biocuriosity or email her at firstname.lastname@example.org.
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