Most expressions of sexual dimorphism in humans are found in height, weight, and body structure, though there are always examples that do not follow the overall pattern. Humans exhibit sexual dimorphism in many characteristics, many of which have no direct link to reproductive ability, although most of these characteristics do have a role in sexual attraction. Sex differentiation in males proceeds in a testes dependent way while female differentiation is not gonad dependent. The SRY gene is normally found on the Y chromosome and is the testis determining factor that governs male sex differentiation.
If a sperm cell carrying a Y chromosome fertilizes the female ova, the offspring will be male (XY). In humans, sperm cells normally carry either an X or a Y sex chromosome. Human males typically possess an XY combination.
Karyogram of human male using Giemsa staining.
