How is immunity like a peacock's tail?
The most interesting thing about this study (in my humble opinion) is precisely what all those news reports didn't talk about. The whole reason the authors cite for doing this study has to do something called the "immunocompetance handicap hypothesis." The idea goes like this: individuals can provide visual proof of fitness (ability to make strong babies), by ostentatiously displaying something that puts them at a competitive disadvantage. For instance, a male peacock with a huge, colorful tail should have a much harder time hiding from and escaping from predators. If a peacock with such a tail manages to survive despite such a handicap, he must be super fit in other ways, and that fitness is irresistible to peahens.
