It has often been cited as a textbook example of a useless body part, but if a scientist is to be believed, belly button beauty may play a vital role in finding potential mates. Aki Sinkkonen of the University of Helsinki, Finland says: "I was younger than nowadays, and some of my friends were discussing how some women have a beautiful umbilicus or navel. "I was thinking, ''How is this possible? If this is scar tissue, how is it possible that it can be beautiful?" Sinkkonen, who published his idea recently in the FASEB Journal, told Discovery News there is plenty of evidence that there is more to the "useless" body part than that. For instance, in many mammals, the navel forms a tiny, asymmetrical scar. However, in humans, it is a visible and significant mark. Many cultures draw attention to it in art, Sinkkonen noted, and some wealthy people pay plenty to have their navel''s appearance enhanced. To reach his conclusion, Sinkkonen pointed out a research by Charles Puckett and colleagues of the University of Misouri, which quizzed people to choose from a number of navels the one that was most attractive. The subjects agreed: the best-looking navels were vertically oriented with a T-shape. Those with particularly large belly buttons, or with any sort of protrusions -- sorry, outies -- or distortions, received lower scores.