“性”乃人类与生俱有的本能,是“天生”的,多数人对性可谓是既了解又不了解,其实“性”是生物的属性,原本并不神秘。原始人类的性行为与其他动物并无区别,是一种公开的行为,不加掩饰,生物进化后,才有了羞耻感,将生殖器部位用树叶围了起来加以遮盖。人类成为高等动物以后,性行为方式渐变隐蔽,异性之间因感情的产生而出现择偶要求,性乱交 “Sex ” is the instinct inherent in human beings, is “natural ”, most people can understand both sex is not understanding, in fact “sex ” is a biological property, was not mysterious. The original human behavior is no different from other animals, is an open behavior, unmasked, biological evolved only after a sense of shame, the genital area surrounded by leaves to cover. Human beings become higher animals, the gradual change of concealed sexual behavior, the opposite sex due to the emergence of emotional choice and sexual promiscuity, sexual promiscuity