It’s total conjecture. I was wondering if the new Pack mentality of the emerging homo sapiens lead to them wiping out the Neanderthals.
It probably started with a form of the punching game, but with prehistoric rules.
There was a theory that early humans learned to exploit and defend in groups sea beds of clams and mollusks. This is one of the few high protein / calorie sources that is small enough for a small group to defend that is worth the effort.
After we started to spread north in Africa and outside of the continent, we had the skillset and language and tools for larger group warfare of dozens of men against a smaller band and groups against each other - making wiping out Neandertals when they competed for food or raped our women a stronger victory.