The bodies of men and women differ from each other, both internally and externally. These anatomical differences across gender, however, are dwarfed by the similarities. The external and internal structures of men’s and women’s bodies are more similar than dissimilar because evolving men and women overwhelmingly faced similar adaptive problems and so the evolutionary selection pressures on the physical makeup of men and women were overwhelmingly the same. Evolving men and women, however, also faced many different adaptive problems, and therefore, many selection pressures on the human anatomy differed across the sexes. These sex-specific selection pressures have produced numerous external and internal differences in the bodies of men and women. Indeed, these differences are so profound that they allow one to easily identify whether a particular individual is a man or a woman.