I was reading an article recently in Scientific American (though it's actually an older work previously published by the science journal). Written by the recently deceased Lynn Margulis, once wive of Carl Sagan, the title alone drew me to the article. But it was Margulis' intriguing evolutionary theory that made the article utterly amazing. Many of us don't contemplate the origins of things like sex. Especially contemplating them back to the very origin of the act on a cellular level. When did organisms at their most basic level stop simply dividing and replicated and begin merging with others. When did it suddenly take two to tango.
Our evolution as life on this floating hunk of rock took a sudden turn as it abandoned immortality and embraced the genetic complexity of sexual reproduction, thus spawning life on Earth as we would come to know it. What I find so wonderfully humorous is Margulis' theory of how this might have happened. It was a simple accident among cannibals. As most interesting stories start.
Check out the full article on Scientific American's website.