Wade frequently states that pre-agricultural humans engaged in war, and then claims that this was a factor in early migration. Yet, there is no clear evidence of war before the neolithic period. He points to contemporary observations of 'tribal' people, like in New Guinea, being warlike. But these people lived in settlements and domesticated plants or animals. Known cultures that have continuously been hunters and forgers since before the Neolithic - such as the Tasmanians and San, are remarkably gentle. And their violence, when it does occur, is between individuals, rather than organized between groups.
I think you raise a good point. He also uses the argument of genetic evidence of 'mad cow' diseases as evidence for widespread cannibalism, but you can get that from eating the brains of any animal.. like from eating cows. People who hunt squirrels used to get that, because they ate the squirrel brians.
It's not exactly settled how "remarkably gentle" the San are. And they are (or were) surrounded by more technological people on all sides, existing only where nobody else wanted to live. If the San are actually "remarkably gentle", then that's a pretty good sign that our more successful ancestors were not the "remakably gentle" ones.
And the Tasmanians and the San were almost effortlessly pushed out of the when more aggressive humans came along. The Tasmanians have totally died off. Any successful population of humanity is aggressive or at least capable of violence when pressed, or they would have been destroyed, conquered or driven away. That's just human nature, or more broadly, that's the nature of groups of organisms that compete for resources. Particularly primates.