Parasites Gave Us Sex -- Now that's a Headline


Ah, the internal parasite, our secret matchmakers. (Vicky TGAW/Creative Commons License)

Yes, the next time you find yourself appreciating the finer qualities of sexual reproduction or shaking your head at its many complications, you can throw all the blame and praise to the worms.

If you happen to pop by this blog enough, you may have noticed that I'm frequently fascinated by creatures who occasionally forgo sex. Some even go ahead and cut the male gender out of the scenario all together.

However, ladies, the danger to either course of action is that asexual reproduction and cloning don't diversify your genetic portfolio. Instead, they lead to stagnation and open a species up to possible extinction from a single successful disease or parasite.

Think of each individual as a combination safe, with a hungry parasite eager to crack the code and crawl inside for a meal. Protecting every safe with the same combination would be madness.

Enter sexual reproduction. According to a study in the journal The American Naturalist (via Scientific American), parasites played a vital role in promoting the evolution and dominance of sexual reproduction. They want to crack the safe, so sex keeps scrambling new combinations.

In the published study, scientists even put this theory to the test by comparing survival rates among populations of a particular New Zealand snail. Some populations reproduce sexually, others asexually. Guess which ones were more ravaged by parasites? Yep, it's survival of the fittest, and sexual reproduction comes out ahead in the end.

Speaking of parasites, fill up on more nightmare juice by watching new episodes of "Monsters Inside Me" Wednesdays on Animal Planet at 9 p.m. EST.

If you want a less gut-twisting education into the ways of these body-moochers, try your hand at the adorable-yet-horrifying Web game, "So You Want a Pet Parasite." I wrote the copy for the game, working with some talented folks from HSW, Animal Planet and Baker & Hill. Trust me, these will be the cutest cartoon characters you've ever seen writhing around in brain and fecal matter.

Experience life with parasites with Monsters Inside Me: Can a Parasite Make Me Sexy? Can My Cat's Poop Kill Me? Are Parasites Controlling Your Brain? 5 Ways Parasites Hijack Their Hosts Menu Items Most Likely to Contain Parasites Meet the Parasites So You Want a Pet Parasite


About the Author: Robert Lamb spent his childhood reading books and staring into the woods — first in Newfoundland, Canada and then in rural Tennessee. There was also a long stretch in which he was terrified of alien abduction. He earned a degree in creative writing. He taught high school and then attended journalism school. He wrote for the smallest of small-town newspapers before finally becoming a full-time science writer and podcaster. He’s currently a senior writer at HowStuffWorks and has co-hosted the science podcast Stuff to Blow Your Mind since its inception in 2010. In his spare time, he enjoys traveling with his wife Bonnie, discussing dinosaurs with his son Bastian and crafting the occasional work of fiction.