Adam was a hybrid human-Isu, conceived in order to preserve the DNA of the technologically advanced beings. He was also one of the first Assassins, along with Eve. In addition, Adam is a distant ancestor to both Clay Kaczmarek and Desmond Miles.
In 75,010 BCE, Adam and Eve, another hybrid, rebelled against their creators. As hybrids, the two were biologically immune to the effects of the Pieces of Eden on their brains, lacking the neurotransmitters upon which the Pieces of Eden acted and that would have compelled them to obey.
Adam and Eve were the parents of Cain and Abel, the former of which would go on to kill his younger brother in order to acquire his Apple of Eden and become the founder of the order that would come to be known as the Knights Templar.