At least for humans, this most basic of acts is anything but basic. As the pioneering sex researcher Alfred Kinsey put it, the only universal in human sexuality is variability itself. Within the universe of intimacy and pleasure that sex affords, however, there's a lot of room for error. From the behavior itself to our sexual identifications and associations, sex never fails to be a provocative topic. Most people are affected by sexual problems at some point in their lives and safety of the body and mind is always a concern. Though the global jury may remain hung over sex's moral and political implications, we can all come to at least one consensus: It's why we're alive today and it's the first thing future generations depend on.