The average baby is about one foot, eight inches long at birth. Over the next twenty years, man triples the length of the body he was born with and reaches an average height of about five feet, eight inches. But why doesn’t he just keep on growing and growing?
In the body there is a system of glands called the endocrine glands which control our growth. The endocrine glands are: the thyroid in the neck, the pituitary attached to the brain, the thymus which is in the chest and the sex glands. The pituitary gland is the one that stimulates our bones to grow. If this works too hard our arms and legs would grow too long and our hands and feet too big. If the gland doesn’t work hard enough, we would end up as midgets.
We continue to grow, but only slightly, after the age of 25, and we reach our maximum height at about the age of 35 or 40. After that, we shrink about half an inch every ten years. The reason for this is the drying-up of the cartilages in our joints and in the spinal column as we get older.
Older people are no longer growing and so they are not as active as they used to be. For this reason they do not need to eat as much and quite often become thinner.