I was doing some research on the Sumerians kings lists. For those that don't know this list has a list of antediluvian kings that ruled before the flood. This list translates to the same as the patriarchs before the flood in Genesis, from Adam down to Noah. Except I discovered one glaring difference! When archaeologists found the stone tablets with the lists on them they seem to all have just 8 names except a list compiled by an ancient historian and astronomer named Berossus. Berossus lived in the late 3rd century and wrote his writings around 290-278 BC. Berossus Kings list had a total of ten names for this period the same amount as the book of Genesis. Could it be that the book of Genesis wasn't written until sometime after 278 BC?
Another clue is the story of Noah's Ark built before the flood. In other stories found in Sumeria, older stories the boat is just a make shift vessel and the measurements are nothing definite more hap hazard. In one story the builder is told to just make it as long as it is wide roof it over and use pitch. In Berossus version the measurements are again not defined as to how the Ark is to be built but are pretty much the exact measurements as that of the Ark in the bible if one is to break them down in to more then one level. much the way the Ark ended up being in the Genesis story.
Could it be that the book of Genesis wasn't written until after Berossus writings, maybe sometime in the 2nd century BC?