This is a comment I received a while back in response to the "Exit Only" post. I thought the question interesting enough that I wanted to post it, and my response on the main page.
AnonymousJune 23, 2014 at 4:06 AM
I've found this blog, and this page in particular very interesting. Do you consider that there could be some element of design or purpose to the fit of the anus to the penis or is this just a fortunate accident? Whatever, it's reassuring to think that I'm not entirely alone in thinking along these lines. The doesn't appear to be a persuasive logical alternative, when you consider the many gynecological disorders experienced by women and the fact that the vagina actually only need to be used a very limited amount of times in order to fulfill its function. And on the other hand you have all these couples who attest that anal provides the greater pleasure for them. Why all the desire and interest if it is not a natural function? I'd love for you to explore this in another post and see if others share this view as I feel you only hinted at the possibility here.