[Excelsior]

(09-06-2013 06:24 PM)Vicious Wrote:  

The problem with the image in the OP is that it assumes that all sex is with the intent to reproduce.

This has not been the case for over a thousand years.

I'd disagree. Though forms of contraception have existed for centuries (longer still if you include the rhythm method), the true separation of sexual intercourse from reproduction didn't come about until the advent of the pill.
Prior to the pill even the most effective methods of birth control could give you a 25-30% risk of failure, and that was assuming you did everything right. There really wasn't much hope for sexual intercourse without incurring a significant risk of pregnancy, as even the most effective methods could leave you with a 1/4 chance of impregnation.

The pill, of course, changed all of this by providing a method that works 99% of the time if properly used. This is a new thing.

Furthermore, the availability of birth control really has little impact on our actual hardwiring. We may have had some form of birth control for many centuries, but aside from the fact that said pre-pill methods were not that effective the truth is that we've been around for much, much longer than that (200,000 years to be more precise, several hundred thousand more if you count the direct predecessors to the homo-sapien). We spent that inordinate amount of time with no understanding other than sex = reproduction because, frankly, there was no other option. Our wiring is still based on that understanding.

You do not overcome several hundred thousand years of biological programming in a millenia. You certainly don't do so in half a century, which is as long as we've had truly broken links between intercourse and reproduction (the pill).

Cultural and geographical variation must also be noted here. Modern contraception has made it possible to break the links between intercourse and reproduction, but modern contraceptives are really only available to a minority of the globe's population and not all of those with access to it make use of it. It can be reasonably inferred that earlier forms of contraception probably varied in their availability as well. Some cultures, probably due to environmental conditions, likely had a greater tolerance for larger families than others and some probably made greater use of contraception than others (I'm quite willing to bet that western Europeans were among the lower large family tolerance and greater contraceptive use side of this equation; other humans are a different story).

This reality regarding the spread of contraception combined with its lack of effectiveness prior to the middle of the 20th century would result in a fairly limited evolutionary force acting on our innate biology, which still understands that sex = reproduction. Overall this is still how humanity is generally hardwired to think, and there's not been much to force an evolutionary shift to the contrary. Again, this may be less true for western Europeans than others (my personal theory), but it still generally applies.