Researcher: One Penis Better than Two

Earwigs. Double penises. Who could ask for anything more?

A Canadian researcher couldn't. In the journal Nature, he writes about how evolution may have conspired to rob some animals of their second penis -- and give precedence to the one on the right.

The full study isn't available online (unless you pay), but Slate got a hold of it and has this summary:

Differences among earwig species suggest males originally had twopenises, but as they increasingly favored the right one, "theless-preferred (left) penis disappeared altogether." High-mindedconclusion: Behavioral changes can drive evolution, not just the otherway around. Translation: Use it or lose it.

And in case you were wondering, "many spiders, dragonflies, shrimp, lizards and snakes have two penises."

Caught right-handed [Nature]

Thanks to Slate!