Signs of Allah in body growth

Our eyelashes, eyebrows, bones and teeth stop growing when they reach a certain length. However, hair does not stop growing. In other words, whereas those body parts the growth of which will be disadvantageous and unsightly stop growing, hair, the growth of which is aesthetically pleasing, keeps on growing. Besides that, there is perfect harmony and proportion in the growth of bones. For example the bones of the upper human limbs do not grow unnecessarily long leaving the body relatively undersized. Their growth comes to a halt just in time as if each knows how long it should grow. Who placed just as much as is necessary of hormones and enzymes in the body thus determining the growth of everything?