Fionn - sure. But my posts, like the way I talk, tend to be a bit scatter-gun, so I need to protect my back from anyone with thin skin! ;-)

Wolfgang and BDP, it does sound a bit strange. Anal sex was certainly used by hetero couples in the past for contraceptive reasons, but since modern condoms and the Pill, there's no need. Certainly it's higher risk than the normal variety, but the number of hetero ppl using it (esp unprotected) is likely to be low, and more due to preference than birth control. The risk for normal sex is lower, but the vastly greater number of hetero ppl having unprotected normal sex is likely to give greater absolute numbers of cases.

Wolfgang, not believing it doesn't mean that you wouldn't like the other person to come up with proof, simply that we don't think they're right. If the other person can say "I'm right bcos..." and give numbers and case studies to prove their point, they've got a much stronger case. If we can then say "Ah, but what about...?" and they say "Here's the numbers for that too", then they're pretty damn watertight.

Your first point is dead right, and backs up the para above. Science is all about testing theories against the real world. Sure, someone can have a far-out theory, and sure, that theory may be right, but we'll only find out if he's right when he proves it.

Not being an expert in the field (well, apart from the obvious on-the-job training ;-) I wouldn't know where to get numbers from, though. Anyone who can give numbers for anything should do so. Do we have any doctors/sociologists/epidemiologists on here?

Grab.