Bartholomew says: "The navel is the midmost place of the body, so called as the shield-boss of the belly (umbo ilium), just as that part of shields is called the boss. The infant is fed as it hangs from the umbilical cord. According to Constantinus [Africanus ], the umbilical cord is made up of nerves, veins and arteries, and by its mediation the fetus attracts and sucks up refined blood, and receives its spirit through those same arteries. The umbilical cord is broken off near the womb when the fetus emerges, and it comes out with the fetus, and the midwives tie it off to a length of four fingers, and from this tying come the ends and roundness of the navel. Thus far Constantinus."

Original Latin

As children, don’t we joke about belly buttons, and ask our friends if they have innies or outies?  Sure - but once we know that they come from the umbilical cord, we learn to say “navel” instead of belly button. 

Bartholomew explains why we have belly buttons - something we all learn about in health class - and his information is more accurate than usual because the sources he cites had first-hand experience with what they are describing.  Today, most of this information is discussed in a doctor’s office.

Do birds have belly buttons, since they come from eggs?  Aristotle knew they do, because he could open bird eggs carefully to examine new hatchlings. 

More interestingly, did Adam and Eve have belly buttons?  Well, thinking they did is one of Sir Thomas Browne’s Vulgar Errors from over 300 years ago.  But the question keeps coming back – try it as a Google search and find some 197,000 hits!