Females Can Limit Male Attractiveness!!

Get ready boys and girls. It’s time once again for a headline torn from the cyber-pages of ScienceDaily.com!

Yes, it seems that the boys have uncovered yet another hitherto undisclosed facet of the evolutionary gemstone, bless their nerdy little hearts.

Females Can Place Limits on Evolution of Attractive Features in Males, Research Shows

Bet you didn’t see that one coming, did you, ladies?

“But… but,” I can hear the stunned stammering already, “how can there be a limit on sheer hunkitude and general all-around buffness? And how can it be possible that we, the women of the world, are responsible for this truly shocking state of affairs??”

Women may have a valid question here. Why can’t males become increasingly more handsome, bigger, fitter, taller and better equipped over time? And why on earth would females themselves limit the evolution of all this increased elaboration?

Part of the answer lies, as it so often does, with frogs and bats.

(The cast of characters)

OK, it goes something like this…

Male frogs, like so many other creatures, ‘sing’ in large part to pick up females. The bigger and better and more elaborate the croak, the more likely frog boy gets to hook up with frog girl. So in order to increase the odds a bit, some male Túngara Frogs (Engystomops pustulosus; the artists formerly known as Physalaemus pustulosus) improvise with more elaborate croak melodies. More is more, right? Well, apparently it sometimes doesn’t work out all that well in frogland.

(Túngara frog belting out a mating melody)

The túngara frog mating call is made up of a longer “whine” followed by one or more short “chucks.” Improvements and elaborations most often happen at the “chuck level”, usually by adding more chucks. In other words, to these frogs, chucks equal chicks. The problem is that, more often than not, the new croak improvises its way right out of the female’s capability to “understand” the ditty. The chicks can’t process all the extra chucks.  The new croaker fails to win over the girls with its sexy ad-libs. Frogs who kick it free-style are naturally selected for extinction by being ‘not selected’ by the females. So it seems that the female túngara frogs are limiting the evolutionary “improvement” of their males.

“But wait!” the women will say at this point. “That doesn’t prove it’s our fault. There could be another reason the new and improved qualities get weeded out!”

And this is where the bats fly in, as it were.

You see, in addition to attracting the opposite sex, the male frog song attracts something altogether different and unexpected… bats! The latest a cappella song on the túngara hit parade is also making its way across the air waves to the well-tuned ears of the the frog-eating Fringe-lipped Bat (Trachops cirrhosus)!

(Cute, eh?)

“Aha!” cry the women. “There’s your answer right there! Bumpy lips digs the new sound, literally eating it up! It’s the predators that weed out the elaborations in the guys, not us girls!”

“Not so fast!” say the research biologists at the University of Texas at Austin. OK, maybe they did not literally say “Not so fast!” Here is what they did say.

The fringe-lipped bats zero in on the male túngara frogs based on chuck number ratio, just as the female frogs do. So, as males elaborate their call by adding chucks, the bats – like the female frogs – are also not turned on and tuned in to the improvement. The more chucks, the less of a chance the frog will wind up as the bat’s main course. Safe yet celibate. Either way, the new-sound froggie is getting some Darwinian chlorine added to his particular end of the gene pool.

(Bat noshing on a túngara tunesmith)

To quote the ScienceDaily article, “”What this tells us is that predation risk is unlikely to limit male call evolution,” says Karin Akre, lecturer at The University of Texas at Austin. “Instead, it is the females’ cognition that limits the evolution of increasing chuck number.”"

In other words, don’t blame the bats, ladies. It’s your fault that guys aren’t getting better as the years go by.  Women prevent us from being all that we can be!

Hey… it’s not me. It’s science!