What might the elaborate courtship dance of male birds have in common with our own male dance partners? More than we might realize.
Think of John Travolta in "Saturday Night Fever'' as he struts onto the disco dance floor in his skin tight jeans and shiny polyester shirt. His moves are pure sex, his performance all exuberant display, impressing the women at the disco as much as those in the theater, watching. As the dominant male in the place, Travolta is desirability personified. Something very primal is being stirred.
The dance performed by the South American long-tailed manakin, as observed in "A Natural History of Sex,'' by Adrian Forsyth, is but one of countless species dances, all different, and all designed for the purpose of attracting a sexual partner. The male birds dance around and the female birds decide if "that's the way, uh huh, uh huh, I like it.''
The manakin has a black body that is highlighted by a turquoise back, a crimson crown and trailing tail feathers that are equal in length to its height. The disco floor, as it were, is a horizontal vine or tree limb. What is unique to this particular species of bird is a song and dance routine presented by two male manakins -- "a leading male and his accompanist'' who join together to pitch woo.
The female is lured over by the manakins' vocal duet. "If the female lands directly on the perch, the two males turn to face her and begin, first one and then the other, to hop up and down, often jumping over each other in leapfrog style. As they leap into the air, they flutter their wings, their tail feathers whip wildly and they utter a buzzing cry. They work themselves into a frenzy until the dominant male of the pair sounds a shrill note. He then slowly flies around the female, and the two mate. The performance is over.''
Do a little dance, get down tonight
An intriguing question is why does this impress the females? How did ridiculously impractical, long tails, coupled with such a vigorous display of talents become a requirement for choosing a mate?
As Adam Forsythe states, biologists have been arguing about this since Darwin. The most accepted theory is that males succeed with females either by battling with, and conquering, other males, or by charming the heck out of them. In other words, if female manakins prefer males with crimson crowns and sumptuous tail feathers, and are dazzled by such aerobic song and dance routines, then over generations, the short-tailed manakins with a limited repertoire simply disappear.
Truth in advertising
But, surely there must be a deeper reason that such courtship behavior succeeds. What is it the females are really learning about their prospective mating partners that makes this display so attractive to them?
The theory is that costly displays (tail feathers that don't improve a manakin's ability to fly, and make them more visible to predators) signal superior health and strength to females. Those exhausting, extravagant theatrics and expensive "outfits'' can only be sustained by the highest quality males. The bottom-line message to the female is that a fabulous, healthy male equals healthy offspring. What you see is what you get.
From the male perspective, those that come equipped with the best tail feathers and have the best act have the most opportunities to mate.
Sound familiar? What we call the alpha males in our human culture -- the guy with the most money, virility, good looks and power -- gets the girls.