Let’s begin by stating that for the record I don’t believe in a global flood, I believe in a regional flood which took place around the Shurrupak region sometime around 7000 years ago, the time when John Walton says the flood happened. Now according to population genetics there was a huge amount of violence around this time, due to warring between patrilineal clans:
I find this correlates very nicely with Genesis 6:11, which states that God sent the flood due to violence on the earth. I will ask, how did the Hebrews know this? The Mesopotamians did not attribute the flood to violence.
For the record I don’t think the flood occured exactly how the Bible says, only that the core is divinely inspired. I think that the story was indeed edited to include a global, rather than local flood.