[classicman]

Intelligent Design: As with all copulating species, female Muscovy ducks battle male Muscovy ducks over which controls fertilization. Patricia Brennan of Yale, writing in a recent Proceedings of the Royal Society B: Biological Sciences, found that the female Muscovy avoids forced sex by having evolved a clockwise-spiraled corkscrew vagina that foils male intruders (but relaxing it for preferred mates, so that they don't get stuck in vaginal "cul-de-sacs"). Brennan's team worked with high-speed video and mock-up glass tubing of the respective organs. [LiveScience.com, 12-23-09]