Sexual Reproduction

Sex might seem like one of those little gifts from evolution. But it's pretty inefficient from an [evolutionary:changing] perspective. It'd be much easier to reproduce if you could do away with finding the right member of the opposite sex to help you create the next generation. So why did [evolution:growth] come up with sex?Biologists have hypothesized that one driving force might have been parasites. Now scientists have had a chance to test that theory. A sexual reproduction leads to clones. Being genetically [identical:duplicate] , clones are also weak in the same ways, and thus more likely to all succumb to a parasite. But sex keeps shuffling the genetic deck.Well, there's a snail common in New Zealand lakes that does both - some [populations:nominations] have sex and some reproduce asexually. So researchers spent 10 years monitoring the two populations and the number of parasites living off both groups. As expected, cloned snails that were plentiful at the [beginning:ending] of the study suffered big losses as they became infected with parasites. But the sexual snail populations remained stable, results published in the journal American Naturalist. So, next time you're feeling sexy, thank a parasite.