There was a great programme from Horizon on the BBC and by the wonders of modern technology you can watch it. BBC iPlayer - Horizon: 2008-2009: What's the Problem with Nudity? Seems that we only put clothes on 600,000 years ago (which means that men have changed their underpants about six times :biggrin1. The theory is that we are supposed to feel shame when we are naked. This keeps us monogamous because kids need us to be because we have such big bloody heads that we have to be born prematurely. Now this begs the question, why didn't the birth canal evolve to say double it's current size so that foetuses could develop to the same stage as other primates at the point of birth. But then if the birth canal was twice the size, would men enjoy sex and bother to be monogamous? or women for that matter. Interesting biological trade offs. Well, there are many interesting questions arising from this programme.