I hate those commercials on cable TV for Enz*te, that fake “male enhancement” product that promises a “boost of confidence” for all the guys who take their little pill. I don’t believe it, of course—it’s probably a concoction of sawdust and rat droppings. But the phenomenon of male confidence as a function of the size of their physical attributes might just have some validity.
AL Basolo, who did some well-known work on mate preference in swordtails a few years ago (short answer: lady swordtails prefer males with longer swords), has a couple of new papers on the subject. She has looked at competition between males—the fishy equivalent of checking out the other guy’s equipment in the lockerroom—and found that the length of the sword makes a big difference in the struggle between males, even with no females involved.
Xiphophorus helleri is a common aquarium fish with a distinctive feature: that long sword on its tail. The males have competitive interactions with each other that are fairly easy to assess: dominant males chase away inferiors, and inferiors avoid the winners, so you just have to record who is chasing who to sort out who thinks they are in charge. Usually, it’s the fish that is bigger overall that wins. The investigators suspected that the size of the sword might also be a deciding factor. Observations of pairs of fish matched for body size, but with natural differences in sword length, did not bear this out, however, showing little correlation. That suggests, as one might expect, that there are multiple factors that influence competitions.
To simplify those factors, they carried out what sounds to me like a very cruel experiment. Pairs of fish matched for body size were anesthetized, their swords chopped off, and replaced with transparent plastic swords of identical size. The difference, though, was that different length swords were painted on the transparent plastic—one lucky fish got a new painted sword roughly the same length as the old one, while the other got a sword half the length.
After recovering from their implant surgery, they were put together in a tank…and the truncated male consistently lost all competitions. I guess size matters, after all.
Without the gross surgical modifications, however, size wasn’t such a clear indicator of victory, so other factors must also play a role. A companion paper looked at stripes on the sword, and how they affected female interests. This work modified the tails digitally; a video recording of a hunky male was made, and then edited to either remove the stripes from its entire length, to remove them from the proximal half or the distal half, or left intact. The video was played back to a female, and the length of time she paid attention to it measured (longer is better).
Female response to the four male video stimuli (pictured above each bar from left to right: complete sword, distal stripes, proximal stripes, no stripes). Bars with the same colour pattern did not differ significantly.
The lessons are clear. Having a long sword will help you intimidate and beat up your competition, and painting stripes along its length (or at least at the tip) will win you the admiration of females.
If you’re a fish, that is.
There is no necessary expectation that it will help at all if you’re a hairless ape, but if anyone tries it, let me know how it turns out.
Benson KE, Basolo AL (2006) Maleâmale competition and the sword in male swordtails, Xiphophorus helleri. Animal Behaviour 71(1):129-134.
Trainor BC, Basolo AL (2006) Location, location, location: stripe position effects on female sword preference. Animal Behaviour 71(1):135-140.
Next step: the use of plastic swords for mate-shoice test, and the use of digitally altered striping patterns in male-male competition tests. I wonder if those are hard to do, or if they tried and got inconclusive data.
The competition test would be hard to do that way — the recording wouldn’t react.
Is there a way to paint stripes on plastic swords?
And I would guess that size-only tests with females would be relatively easy.
I suppose the next step is to paint stripes on the “swords” of grad students and see how males and females react. Heck, it’ll be intersting enough to see how the subject grad students react when they sober up and discover the stripes.
“(Longer is better.)” You did that on purpose.
I’m a bit thick today, and I think your comment is too deep for me.
I think the suggestion is that the text just there doesn’t read at all well unless that last little phrase is made into a separate sentence – even one still in parentheses.
PS (ie what I was originally going to say before reading the comments and getting distracted!) Poor fish, having their dangly bits chopped off. :-(
I heard there was a study where they determined that female swordfish did not care so much about the length of the sword as how well it was used.
And I heard it had something to do with circumference….?!
What, no “motion of the ocean” double entendres? We’re talking about fish, so it’s the perfect innuendo. I’m disappointed in you people… *LOL*
“and painting stripes along its length (or at least at the tip) will win you the admiration of females.”
I guess it’s a UM-Morris thing. When I was in school we just used bad poetry and cheap wine.
It is good to know that video is not meaningless blur to fish.
Hey PZ we are merely thin-haired monkys.
Newly discovered worm fences with penis
Hey, what happened to the link? I’ll have to try again.
Newly discovered worm fences with penis
http://www.sciencedaily.com/upi/index.php?feed=Science&article=UPI-1-20060120-17085600-bc-australia-creature.xml
Good Elvis Almighty, the whole study sounds like a setup for a Bill Hicks routine. This doesn’t downplay the research: if anything, it confirms that we humans have far too much sex on the brain. “You the guy payin’ for the bobbin’ finless swordfish movies?”
It turns out that size also matters for male bats:
http://www.msnbc.msn.com/id/11007037/ .
In promiscusous species, male bats trade brain size for testicle size. In monogamous species, female loyalty allows the males to afford larger brains.
I knew there was a good excuse for this monicker…
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