Woman has greater constitutional vitality, perhaps because of this chromosome difference. Normally, in the United States, she outlives man by three or four years. The sexes differ in their basal metabolism that of woman being normally lower than that of man. They differ in skeletal structure, woman having a shorter head, broader face, chin less protruding, shorter legs and longer trunk. Boys' teeth last longer than do those of girls.
Women have a larger stomach, kidneys, liver and appendix, and smaller lungs.
In functions, women have several very important ones totally lacking in man menstruation, pregnancy, lactation. All of these influence behavior and feelings. Woman's blood contains more water and 20 percent fewer red cells. Since these supply oxygen to the body cells, she tires more easily and is more prone to faint. In brute strength, men are 50 percent above women.