I really dislike the "human nature" argument, because it is mostly used to basically exonerate the ones who actually did conquer and destroy other cultures. Yes, history would probably be the same, had the roles been reversed. But in this world, they weren't, and the ones who did obliterate an entire continent's culture and most of its population, were the White Men. Just because it is "human nature", doesn't change that fact.
Also, what book is that? Sounds cool.