Why do humans and so many other species reproduce by having sex? If you think about it, a case could be made that asexual reproduction is faster and more efficient than sexual reproduction in a lot of ways (I mean, at the very least, reproducing asexually saves time by eliminating the need to find willing partners). To the extent that this is true, then why did so many organisms evolve to reproduce sexually?

"Science Guy" Bill Nye explains why in the video below. In a nutshell, the theory he describes is that sexual reproduction creates far more genetic variability than asexual reproduction and that this enhanced genetic diversity allows organisms to put up a more effective defense against germs and parasites. In other words, although sex may be a less efficient form of reproduction, it offers survival benefits that offset its lower efficiency. Check out the full video to learn more about this fascinating theory.