Friday Weird Science: Rats in PANTS

Feb 18 2011 Published by under Friday Weird Science, Uncategorized

Today’s Friday Weird Science comes to us courtesy of ProfLike Substance, who passed on this truly GLORIOUS paper to Sci many weeks ago. I’ve been dying to blog it for ages, but other things (like whale penises) seemed to always come up (you see what I did there) and required immediate blogging before someone else got to it. But finally, FINALLY I get to sit down with what may be the most adorable paper, from the weirdest laboratory ever.

So men, have you ever really THOUGHT about your pants choices and the effect they could have on your sperm? Boxes vs briefs? Wool vs denim vs polyester? Why haven’t you!??! Cause this guy has.

Behold: rats wearing pants.

Shafik. “Effects of different types of textiles on sexual activity” European Urology, 1993.

From the actual paper! How cute is that?!!?

The work in this study is based on previous work in humans and in dogs (which Jason and I both covered in one very EPIC day on blogs and twitter. Hehe, recepticle for your testicle…hehehehe… why haven’t these guys won the IgNobel yet?!) showing that the wearing of polyester underpants caused a decrease in sperm count down to almost zero after a continuous wearing of 5 months in humans. Cotton underpants had no effect. The authors thought that electrostatic potentials from the polyester were to blame, and this author claims that the potential temperature effect was minimized due to features of design. From my reading of the paper, I didn’t get that at all, and in fact there was a significant temperature increase. Oh well.

Anyway, much as humans are unlikely to be wearing pure polyester underpants, they do wear blends, and some guys do like to go commando. And so this guy undertook a massive study, using 75 rats, a lot of cotton and polyester, and a very tiny little sewing machine, to see what effect different types of pants might have on sexual behavior in rats.

Really, I’ve got to wonder why we didn’t just go straight to humans here, and look at libido changes with continuous wear of different kinds of underpants. Possibly because it’s hard enough to get volunteers for that kind of study without asking them how horny they are…

I’ve got to think that this guy’s lab must be the CUTEST lab EVER. You’d need a washing machine for the pants. Little sewing machines for the rat pants. Maybe a little closet full of little rat pants! The possibilities are endless. Also kind of gross. I can only imagine what those rat pants looked like at the end of the day…

So he took 75 rats and divided them into five groups. One group hung proud and free. The second group got pure polyester pants (hopefully in a variety of delightful paisley patterns). The third group got a 50/50 blend of polyester and cotton, the fourth got cotton, and the fifth, long-suffering group of rats got 100% wool. The rats wore the pants for 6-12 months

The pants had openings for the penis, butt, and tail, but I have to wonder how effective those were. I mean, the pants GOTTA stay on, so they need to be kind of tight. But then, I imagine the penis and anus holes didn’t work very well. I imagine this author had to wash a LOT of little pants.

After 6 and 12 months, the rats were put with ladies, and tested for their sexual behavior. What we’re looking for is changes in intromission and mounting. They were also rated as “potent” if the males got an erection and entered the female, and “impotant” if they got on the lady, but couldn’t get it up.

And of course the data is ALL in tables. Look what I do for you. I graph because I love.

(Edit: The stuff had to be regraphed because I was tired and screwed up the figure legends. These are the correct ones. I think. I'm only a little less tired now.)

You can see that the number of mounts (times the rats intended to get it on), and intromissions (when they succeeded). The polyester and cotton polyester blends had the biggest effect, with a real decrease in sexual behavior, while the cotton, wool, and commando groups did just fine. The mounts increased (oh those poor boys are trying!), but the intromissions decreased (FAIL).

The author also looked at the electrostatic potentials, and noted that there weren’t any produced in the wool, cotton, or commando groups, but that the polyester and cotton/polyester blend groups both had significant electrostatic potential. The author hypothesizes that the electrostatic potentials themselves were communicating through the skin into the corpus callosum of the penis, and causing the rats to exhibit erectile dysfunction.

Sci’s not so sure about this. IS it the electrostatic potential? What about heat? And what about the severe embarrassment of wearing polyester pants? Also yes, there was a decrease in sexual activity, but they didn’t look at any potential decreases in sperm count or sperm motility, nor did they take the temperature of the rat’s balls to see if they were higher than normal. So sexual behavior is down, but is heat up? And what about the sperm count (I think it’d be down, but I’d like to see). Is there a way to create an electrostatic potential like this WITHOUT heating the balls, to see if the decrease in sperm count is actually due to the heat? And is there a way to do this without creating some very uncomfortable rats?

Because hey, maybe the rats were just SERIOUSLY UNCOMFORTABLE. After all, they were wearing POLYESTER PANTS continuously for a year!! Can a rat get a kilt or something?

Maybe electrostatic potentials are themselves uncomfortable?

So who knows whether the net result should be a worldwide ban on polyester underpants, and whether electrostatic potentials are making these rats go limp.

Shafik A (1993). Effect of different types of textile fabric on spermatogenesis: an experimental study. Urological research, 21 (5), 367-70 PMID: 8279095

22 responses so far

  • idlemind says:

    You graph labels seem a bit off; "cotton/polyester" appears twice.

    And if they were concerned about electric charge, how about undies made from aluminum foil?

    • scicurious says:

      Yeah, sorry, the first set on the left is free-ballin, then polyester, THEN cotton/polyester. Blame my graphing autofll.

      • Andrea says:

        I'm still a bit confused about your graph. Where does cotton come in? You say free-ballin' is on the left, but isn't it the "commando" on the right?

        Great article, but could you just reiterate, left to right, what all the columns should be?

  • Paul says:

    OK, now I have seen it all!

    I think the mental image of thousands of little rat pants going around in a washing machine will be with me for days.

  • proflikesubstance says:

    All those little pants would SO get lost in the dryer.

    FWIW, I would support a world wide ban on polyester pants, no matter what the data say.

  • mod.cur says:

    I wouldn't think you'd need a ban on polyester pants, one look at the data and most guys wouldn't wear them if you payed them. Maybe that's why this hasn't won an IgNobel yet, big polyester is suppressing the data 😉

  • There's no possible chemical reason is there? It seems like they're finding more and more plastics that were thought to be fairly stable actually give off volatiles, especially when heated.

  • gerty-z says:

    OMG! I totally did this article for journal club when I was a wee grad student. It was totally unrelated to my project and field of study. But it was RATS IN PANTS! Love it. And thanks for the graphing. I have no idea why anyone puts all their data in tables.

  • gerty-z says:

    Also, why are cotton pants "better" wrt intromissions than free-ballin? i would assume that rats would be best off commando.

    • scicurious says:

      No significance in the data there, the increase you see is before the pants. Though I don't know, maybe the look and the feel of cotton, the fabric of our lives, makes the rats more comfy? Perhaps prevention of abrasion from normal ball to ground scrapage? 🙂

  • So, I am confused about the libido hypothesis...they measured mounting behavior as an indirect indicator of libido (and you mentioned this is a potentially tricky self-reporting issue if the study were to go straight to humans), which suggests that lower was one outcome they expected from some types of pants. But, if temperature is to blame, I'm not sure libido comes into play at all.

    Increased temperature = decreased sperm count. High temps inhibit spermatid development. We know this from other studies, and so the effect of different materials seems relevant to this variable.

    However, I don't think that there is any solid evidence that increased temperature = decreased libido. As a gross oversimplification, libido is dependent upon testosterone. Testosterone is made by Leydig cells. While there are cases in which failed Leydig cell development is correlated with high temps and therefore decreased sperm count (cryptorchidism springs to mind), this does not necessarily imply that decreased libido is an expected (or observed outcome). When the testes are retained in the body cavity, this is due to Leydig cell dysfunction which may be decoupled from testosterone production. Testicular descent requires both testosterone and insulin-like 3 peptide (both Leydig cell products). So, if there is no Insl3, testosterone production may proceed normally (and one could hypothesize that libido would not be effected, but the testes are retained in the body cavity, increasing the temperature and decreasing sperm count. (Of course, failure to produce testosterone could also lead to undescended testes AND decreased libido.

    But I think that temperature alone (as in the case of rats in pants) would effect only sperm count and not testosterone production, no?

  • idlemind says:

    I highly doubt that electrostatic fields have anything to do with this, since they aren't going to extend farther than the skin's surface. I'd put the idea right up there with the claims about the orgasm-enhancing properties of the piezoelectric effect in pubic hair (a claim I saw in a pop psych magazine a decade or two ago). Heat, discomfort, less accommodating behavior on the part of female rats (not unlike the reaction in humans to polyester pants) -- all more likely explanations.

    • scicurious says:

      I have to agree with you that I don't believe the electrostatic bit until I see it. There are far too many charges going on in human skin and cells for small electrostatic potentials to be fooling with them deeper than skin level.

  • Emily says:

    I clicked on your PubMed citation at the bottom, and it took me to a different study, I think by the same scientist, this time putting underwear on dogs.

    I wonder how many different animals he got to put pants on...

  • scicurious says:

    Posting comment on behalf of Dave at

    "corpus callosum of the PENIS" (wtf?) i think you mean "corpus cavernosum"... unless rat peni are a hell of a lot smarter than mine.

    as for the article, tldr did they talk about why there's such variance in the control groups? looks more fishy than ratty.

    And yeah, he's right...I mean cavernosum...unless your penis is especially brilliant. 🙂

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