Paleolithic penises can tell us about the origins of genital piercing, and also about ourselves

At what point does sex cease to function as a purely practical means of reproduction? In other words, by what process does sex become something more than just a biological imperative; when do things like eroticism and sexuality emerge in an anthropological context?

Sex and sexuality have obviously been well-established cornerstones of humanity's collective social experience for some time, so answering questions like these is understandably difficult. And yet, logic dictates that there was almost certainly a point in time when our ancestors first started to relate to sexuality in ways that differ from the rest of Earth's species. So when might such changes have occurred?
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