The fetus and newborn considered as water-babies

摘要

We have all seen pictures of an unborn fetus sucking its thumb in the womb. So why does it take the average newborn baby about eight weeks before it can do the same again? The human newborn, compared to other primate babies, is born with very unfortunate body proportions which make the production of coordinated movements difficult. First of all, in order to accommodate the large human brain, babies are born with a head a quarter of their total body size. Imagine having to go around your daily business with a head the size of a large watermelon on your shoulders! Secondly, our newborns are born relatively fat to make up for the fact that we do not have any fur to keep us warm. Add to this that the human newborn has been floating around in a watery environment for the past nine months which has made it impossible for the baby to build up muscles strong enough to cope with gravity, and you end up with a recipe for disaster when it comes to the control and coordination of early movements.