I did not downvote the parent.

My claim: almost every human adult has had at least one sexual partner. I can only find decent studies surveying modernity, but for example: http://www.nbcnews.com/id/19374216/. Assuming most humans having sex is not a recent development, any evolutionary pressures, if they exist at all, on the sexually active population are unclear at best; however, there may be pressures against the tiny few who go through life abstinent.