proportion may not exist between men and women. These findings made him rule out the possibility that a preference for women with proportionately longer legs than men is due proportionately longer legs being a secondary sex characteristic of women. Genitalia A 2006 study of 25,594 heterosexual men found that "men who perceived themselves as having a large penis were more satisfied with their own appearance". A 2014 study criticized previous studies based on the fact that they relied on images and used terms such as "small", "medium", and "large" when asking for female preference. The new study used 3D models of penises from sizes of long and in circumference to long and in circumference and let the women "view and handle" them. It was found that women overestimated the actual size of the penises they experimented with when asked in a follow-up survey. The study concluded that "women on average preferred the penis in length both for long-term and for one-time partners. Penises with larger girth were preferred for one-time partners." Evidence from various cultures suggests that heterosexual men tend to find the sight of women's genitalia to be sexually arousing. Skin color Manual laborers who spent extended periods of time outside developed a darker skin tone due to exposure to the sun. As a consequence, an association between dark skin and the lower classes developed. Light skin became an aesthetic ideal because it symbolized wealth. "Over time society attached various meanings to these colored differences. Including assumptions about a person's race, socioeconomic class, intelligence, and physical attractiveness." Some research has suggested that redder and yellower skin tones, reflecting higher levels of oxygenated blood, carotenoid and to a lesser extent melanin pigment, and net dietary intakes of fruit and vegetables, appear healthier, and therefore more attractive. However, there is little direct evidence that skin colour is actually related to health or immune system strength. An historical preference for lighter-skinned women has been documented across many cultures. However, the accuracy of this research has been questioned by other authors. Experimental studies show that white Western men are more attracted to dark-tanned women, rather than medium-tanned or pale women. A 2010 study found a preference for lighter-skinned (but not lightest} women in New Zealand and California, however other research has found that African-American males and females consider medium complexion as more attractive than lighter or darker skin, while white and Hispanic women