No it has not evolved has some have said. It has gone backward as we get more civilized. The cavemen did not care about there partners sex, just that it felt good. There are cave drawings of all sorts of coupleings and from just two people to large numbers involed. With religion we got restrictings. But even the Bible say that Adam and Eves children had sex with each other to populate the world. Noah's grandchildren had to have sex with each other to repopulate the world. People just do not like to think of that part of the meanings in the Good Book.

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