Podcast Transcript: If you’ve ever given any thought to the lifestyle of the hermaphrodite, it’s probably occurred to you that being both male and female doubles your chances of having a date on a Saturday night. Yeah, it’s an old joke, but it’s sort of true. Because most hermaphrodites do have to date. In other words, they can’t simply fertilize themselves. (If they could, I’m sure they would.) So what actually stops them? I mean, what keeps a hermaphrodite from mixing together its own sperm and eggs, and then staying home to watch TV?
In the March 20 online issue of Science, researchers from Japan reveal the answer. They were studying the sea squirt, an animal that reproduces by spewing sperm and eggs into the water and leaving the rest to chance. Combing through the sea squirt’s genome, the Japanese scientists discovered two sets of genes. One produces a protein found on the egg’s surface; the other makes a similar protein on sperm. When these molecular calling cards hail from different animals, the proteins come together and allow fertilization to occur. When they’re from the same animal, they politely shake hands and go their separate ways. Now if only humans had such a simple system for figuring out who to bring home to mother.