Natural selection works on particular physical characteristics of humans and how they perceive them since these features affect how many offspring an individual may leave behind. There are differences in the strategies males and females adopt to maximize their attractiveness and the reasons for finding specific characteristics attractive. Despite these differences, there is considerable agreement between different cultures and males and females regarding which individuals possess beauty. Furthermore, the pattern is repeated globally: individuals judged attractive garner a higher share of resources and produce more offspring than their less beautiful peers. At least three mental modules are involved in evaluating the beauty of faces. These modules are embodied in various parts of the central nervous system. The systems identified so far are an identification module, an interpretation module, and a valuation module. The factors that influence the outcome include age, how healthy the individual appears, how symmetrical the face is, how similar to average the facial proportions and those of the body generally are the color of the face and skin texture.