You knew there was a reason those earrings kept getting bigger didn’t you. Though the New Scientist article seems to be all about males. Bigger baseball caps anyone?
Most body parts grow proportionally with the rest of the body as individuals of a species become larger, although scientists have long known that visual cues of reproductive prowess are a special case.
Now, in the largest survey to date, James Brown at the University of New Mexico, Albuquerque, US, and his colleagues have examined the proportions of 284 ornament-bearing species to see whether the tendency was truly universal. They found that in virtually every case, ornament size grew by roughly the square of the overall growth rate.