I asked this guy from another message board if sexual reproduction usually equals pleasure? and he replied with this: "It's not only sex; eating, drinking, exercise, our bodies are programmed to release endorphins and create pleasure to reinforce actions which aid its survival and propogation. I cannot see how any being, sentient or otherwise, that is capable of not performing those actions could not be so programmed." I agree with him on the first part but I think there are alot of non sentient animals out there that breed without feeling any kind of pleasure, or am I wrong? So he I think he is saying that pleasure arises as a motivational factor, I guess...it did for us.