Why do we keep our belly buttons all our lives, while in most mammals who nurse their young, these disappear when they mature? Scientists think they indicate the mating potential of fertile women.
During pregnancy, the umbilical cord supplies a baby with nutrients and oxygen from the mother. After birth, it’s clamped and snipped, leaving a short stump that eventually falls off. It’s not known exactly why there are so many shapes of belly buttons. Most people prefer belly buttons that don’t protrude.