Another of these stupid religious/bible questions, such as how many angels can dance on the head of a pin. All mammals have belly buttons. Despite religious wacko unfounded beliefs, we are mammals; we have bellybuttons. There was no one person "Adam", but if you arbitrarily decided some person in the past was "Adam", he would have had a bellybutton.
Conservatives complain about how the education system of, say, the U.S. is deteriorating. They should look to themselves as well as the woo-hoo liberals for reasons for the decline. To spell it out, their (religious conservative) wacko, unfounded in reality, unswerving belief in "God" and the stories in the Bible contribute in a major way to general ignorance.
I can't believe I devoted this much time to answering a totally stupid and ignorant question. Back to work after this.