March 26, 2008 | David F. Coppedge

Peacocks Don’t Dress for Success

The male peacock’s fancy feather show: an icon of Darwin’s theory of sexual selection, right?  Then why did Japanese scientists tell Discovery News that the females pay them little attention?
    The article claims that the male’s appearance fails to interest, much less excite, the females, who seem to pay more attention to his singing.  “The determination throws a wrench in the long-held belief that male peacock feathers evolved in response to female mate choice,” the article says.  “It could also indicate that certain other elaborate features in galliformes, a group that includes turkeys, chickens, grouse, quails and pheasants, as well as peacocks, are not necessarily linked to fitness and mating success.”
    What’s more, the scientists, who observed peacock mating displays for six years, could not find a correlation between the attractive males and their fitness.  Females were seen to run around males they preferred and get them to shiver their feathers.  These were not the ones with the most elaborate displays.  They speculated that maybe the fancy feathers are obsolete mating signals, and that vocalizations are now more important.
    They realize this is controversial and more testing will need to be done.  A UK scientist added that the feathering display, which is a function of hormone levels, is a poor indicator of fitness, both at the gene level and in the mature bird.
    How, then, can a scientist say female dinosaur’s were attracted to a male’s frill?  MSNBC News quoted Terry Gates at the University of Utah Museum saying this: “That whole section of the head was for sexual display, it was all ornamentation.  The females liked it.”  The article proclaimed the line: “Ladies lured by dinosaur’s giant horns.”  But if we cannot be sure living birds are attracted to one of the most elaborate and beautiful examples of sexual dimorphism, how could anyone understand what an extinct dinosaur found attractive?

It’s impossible to get into the mind of a peahen or dinosaur and see what is affecting her choice of mate.  Still, this is a big blow to a major speculation that made Darwin famous.  Charlie has had orders of magnitude more fame than the usual fifteen minutes, and most of his ideas have been defrocked like a plucked turkey.  Can we move on?

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Categories: Birds, Dinosaurs

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