Yup. People really need to start think in terms of speciation in my opinion. My view is that there are at least 7 completely different species of human on the planet and I classifay north american indians as their own species. Look, culturally, you don't just one day wake up in your tribe and decide to start raiding tribes, killing everyone, raping everyone and scalping everyone as a just a larp. Also, you don't just one day wake up as an Aztec priest and invent industrial scale sacrifice like the Aztecs and all of their kin were known to do. All culture, behaviours and beleifs are downstream of genetics. In evolutionary terms, there is a co-relation between the survival of the fittest and the past behavioural / competitive pressures that result in not only speciation but specific preferences for natural behaviours that end up becoming expressed as dominant features in a gene pool. The scalping, raping and human sacrifice may not have started out in their species as a defining feature, but once it began it self selected for genetics that favoured ever more aggressive forms of these behavioural features until they had become dominant and embedded in this species of human. As per your post, natives in south america still practice human sacrifice only with different tools. There is NO MYSTERY to why south american is violent at the level that it is. Similarly, while north american indians did not practice human sacrifice to the degree their southern cousins did, they did have a huge scalping, raiding and raping culture. Speak with ANY white nurse that had to work for any period of time on any native reserve and they will tell you that native north american indian reserves are nothing but rape societies. There is a reason that north american natives refer to each other as cousins. These are not accidents. Similarly, there is a reason that shitskins are just as violent, it's been embedded in their genes through 1000s of years of violent selection. There is a reason they are all hook nosed and fucking ugly. Obviously they are violent in a different way from american indians, I would venture to guess that not only can violence tendencies become embedded in a genome, evolution can select for the kinds of violent tendencies as well.