Why do bowerbirds build such crazy architecturally adorned structures? Why do so many male insects have such fancy horns and colors and patterns? What's up with the male peacock's tail?
Throughout the natural world there are an abundance of cases where males and females of the same species look very different - a phenomena known as "sexual dimorphism." Darwin came up for a very interesting an powerful explanation for this based on his principle of natural selection.
He reasoned that the individuals of a given sex may have to compete with each other to attract potential mates, and so that one (or the other) sex might evolve adornments and behaviors to attract these possible partners. This is known as "sexual selection," and while males often are the sex that is acting so flashy and with all the bling, in some cases the roles are reversed.
Of course, since humans are themselves evolved from the same "Tree of Life" as all other creatures, might they not also be subject to sexual selection? Perhaps we too choose mates on the basis of displays that signal biological worthiness?
This zine, a "The Mini-Book of Sexual Selection" by SSC contributor Dominique Holmes gives a nice little introduction to these questions... Feel free to click on the pink zine cover
above to download a copy.