We know that beautiful hair in a woman can be very attractive, but we must assume that hair on human beings formerly played a more piratical role than it does now. When a baby is born he is covered with a fine down. This is soon replaced by the delicate hair which we notice in all children. Then comes the age of puberty, and this coat of fine hair is transformed into the final coat of hair which the person will have as an adult.
The development of this adult hair is regulated by the sex glands. The male sex hormone works in such a way that the beard and body hair are developed, while the growth of the hair on the head is inhibited, or slowed down in development.
The action of the female sex hormone is exactly the opposite! The growth of the hair on the head is developed, while the growth of the beard and body hair is inhibited, so women don’t have beards because various glands and hormones in their bodies deliberately act to prevent this growth.