There are good reasons why our physical features play the greatest role in flirtation and our brains are tuned to respond to them. Just as peacocks are primed to pay attention to elaborate tail feathers, women may quiver at the sight of men with large, even features, square jaws, and big bones. They may actually rate such men as better prospective sex partners. One theory is that all of those large features are also signs that the creature has an immune system healthy enough to support such extravagant apparatus.
Similarly, by flaunting, say, our curves and swinging our hips from side to side as we sashay down the street, we do more than announce "I am an attractive and available woman." We call attention to important attributes. Scientists have established that a small waist coupled with ample hips � very curvy proportions � is a sign of both health and fertility in women. It's nature's way of declaring the likelihood that we are capable of bearing children and surviving to raise them. After all, nature has a big stake in the attraction matter � nothing less than the continuation of the species.
When a relationship gets under way, courtship follows, and two people can then apply more rational criteria in deciding whether a particular partner is lifetime-mate material. Also, more subtle signals come into play, like humor, intelligence, creativity, emotional sensitivity, and expressiveness. After all, they, too, figure prominently in our ability to survive the relatively complex lives we lead today.