A long read. And, maybe I dozed off a bit. But, a couple points/questions:
I'm not sure I understand the logic of using the ancient writings of a primitive people with oral histories and no evidence to debunk or contradict the ancient writings of a primitive people with oral histories and no evidence. I don't accept anything in the Bible, or any other ancient writings without a huge amount of support and evidence. I also find it interesting that you do not discuss the dieties Brahma and his wife Istar (Abraham & Esther) of Sumeria whose son Yahwey became the god of the Hebrews. Not that I believe that, I just found it curious.
Secondly, and more importantly, there may be a bit of a Chicken & the Egg argument here. It is with rare exception that evolutionary anthropologists and biologists agree that it was scavenging remains of animal kills that is the reason our brain development happened. Without the meat protein our brains would not have grown and developed to their current complexity. And there would have been no natural tendency to evolve. It was this activity that created the need to use tools (break bones to get marrow, cut away meat from bone, etc...). Hundreds of thousands of years later, it also made use of fire (as it makes the meat easier to eat and digest) a source of safety and community, thus allowing our species to survive.
Now, it may be possible that had the right plant proteins been available in Africa they may have had the same effect on brain growth. But, the proteins are not identical, even though they may be compatible and similar. But, the use of tools and expansion of creative thinking may never have happened.
There is no way to answer that, short of a time machine. But, I believe your position suffers the same consequence.
As to the violence - I think there is a lot of credibility to the idea that it was hunting that made a change in our evolution. And, perhaps not for the better. However, there were many positives to hunting in terms of community, family, and further brain evolution. You can make the argument that without hunting we my not have become violent (although I don't think you can prove that). But, you also can't ignore the truth of our evolution.
Ceasing the eating of meat, worldwide, it would still take countless generations to rid those genes, the knowledge, and the instincts from our brains.
And lastly, sorry I can't avoid mentioning it, why even mention atheism? That Atheism Debunked movie (I skipped around, could not handle most of it) is one two-hour long Strawman Fallacy - and rather silly. Of all the people, atheists are the least violent, the least likely to commit crimes, etc... Even hinting otherwise is dishonest.
"In the beginning of a change the patriot is a scarce man, and brave, and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot."--Mark Twain
Want DP delivered to your inbox daily? Subscribe here: