Why Is It, That We Stop Growing?

The average baby is about 50 cm, at the time of birth. In the next 20 years that follow, man adds to the length of the body, he was born with and attaining an average height of about 168 cm. Why he does not keep growing. There is something that stop the growth of body. The system of glands in our body called endocrine glands controls the growth of our body.

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 stimulates our bones to grow. If this gland works too much, our arms and legs grow too long and our heads and feet become too big. If the gland does not work hard enough, we might end up as midgets.

A child is born with a large thymus gland. It continues to get bigger during childhood. After the age of 13 or 14, the thymus gland begins to shrink. As long as the thymus gland is working, the sex glands are small. With the development of sex glands, the thymus gland stops working. This is the reason, why a person stops growing, after attaining sexual maturity at the age of about 22.

In some cases, the sex glands develop too soon and blow up the thymus gland too early. This often makes a person below average in height. Since our legs grow later and grow more the other parts of our body, this early development makes the legs short. This is the reason why people who develop too early are often thickset. Napoleon was an example of this kind. 

If the development of sex glands is delayed, the thymus continues with growth and the person becomes taller than the average. Actually our growth process continues even after the age of 25 years. Our maximum height is attained at the age of about 35 or 40 years. After that we shrink at the rate of about 13 mm. every 10 years! The reason in this is simple, the drying-up of the cartilages in our joints and in the spinal column as we get older.