The more highly developed musculature in men marks the skeleton more. Many Anatomical differences in naked men examples exist: Women have better night vision, better visual memory, and can see more of the red end of the color spectrum than men can. These studies have been criticized for their small sample sizes, and the findings have not been confirmed. This was widely reported to mean that women are better at multitasking, Anatomical differences in naked men though subsequent work has failed to replicate the results. For this reason, scientists believe it is exposure to estrogen before birth that somehow "programs" the lightening of female skin during puberty.