How is the belly button?
From a genetic point of view, the navel doesn't exist: no genes responsible for its shape, size, convexity. This acquired feature, as well as any scars. During pregnancy, the fetus attached to the placenta, a special umbilical cord, by which the baby receives nutrients and oxygen, and back – waste. Thus the embryo is associated with the mother's body.
After birth the umbilical cord is no longer needed – the child has become an independent person and he can breathe, eat, drink. The doctors cut it near the belly: the result is a wound which quickly heals. In its place a round scar, which is called the navel.
In animals, the belly button is almost not visible: it is a thin line with no hair.
Why you need a belly button?
All the organs in the body have their purpose and perform certain functions, but their activities down to the smallest detail "spelled out" in the genetic code to the body function correctly. As in the human genome, the existence of belly button not checked, you can make a logical conclusion that the purpose of this body part no.
However, people learned how to use navel in those or other purposes. First, its form can distinguish identical twins that have almost identical appearance. These scars are acquired, they do not depend on genetics, so even twins are different. Second, the navel serves an aesthetic function: abdomen with a neat round hole looks nice and according to some people, sexy.
The navel is decorated with special earrings, making the piercing.
But the most useful function of this body part associated with medicine. Doctors have learned form the navel to detect some of the disease. For example, if it bulges upward, this may indicate increased intra-abdominal pressure or enlargement of some internal organs – liver, spleen. Also this form has the navel in people suffering from internal obesity (accumulation of fat around the organs, not under the skin). If the navel stands out significantly, despite a small amount of fat is evidence of possible irregularities in the structure of the lumbar spine. Form and status of this scar can be identified and an umbilical hernia – protrusion of internal organs through it.
In some religions and esoteric teachings the navel is the center of domestic energy. For example, the Chinese believe that at this point is going to the qi energy that circulates throughout the body.