we are relatively hairless which leads to more sensitivity to touching and feeling. our lips are turned outwards unlike other species which again leads to increased sensitivity at our lips. our females have permanently inflated mammary at all times unlike our primate cousins. our coitus is long and involved compared to most other species. what does all this mean? that we as humans were built with extreme sexuality in mind. it makes sense that those that had more sex reproduced more and it became survival of the sexiest. males probably sexually selected those females that had permanently inflated mammary and mated with them more so than with others. bare skin must have been attractive as well. you are designed to be sexy.