Other Body Differentiation
The differentiation of other parts of the body than the sex organ creates the secondary sex characteristics.
General habitus and shape of body and face, as well as sex hormone levels, are similar in prepubertal boys and girls. As puberty progresses and sex hormone levels rise, obvious differences appear.
In males, testosterone directly increases size and mass of muscles, vocal cords, and bones, enhancing strength, deepening the voice, and changing the shape of the face and skeleton. Converted into DHT in the skin, it accelerates growth of androgen-responsive facial and body hair. Taller stature is largely a result of later puberty and slower epiphyseal fusion.
In females, in addition to breast differentiation, estrogen also widens the pelvis and increases the amount of body fat in hips, thighs, buttocks, and breasts. Estrogen also induces growth of the uterus, proliferation of the endometrium, and menses.
The difference in adult masculine and feminine faces is largely a result of a more prominent chin, heavier jaw and jaw muscle development and thicker orbital eyebrow bossing. Masculine features on average are slightly thicker and coarser. Androgen-induced recession of the male hairline accentuates these differences by middle adult life.
Sexual dimorphism of skeletal structure develops during childhood, and becomes more pronounced at adolescence. Sexual orientation has been demonstrated to correlate with skeletal characters that become dimorphic during early childhood (such as arm length to stature ratio) but not with characters that become dimorphic during puberty—such as shoulder width (Martin & Nguyen 2004).
Read more about this topic: Sexual Differentiation
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