The evolutionary purpose for these traits is success at war. Darwin knew that humans were a special case, that the discovery of war is what caused humans to develop intelligence far in excess of what is needed to find food. If two tribes go to battle, usually the smarter tribe wins, and the genetically inferior tribe dies off. And it isn't just intelligence, but group loyalty, self-sacrifice, cooperation, morality, even lifespan, are all genetically honed for success at war. War is in effect very high speed evolution, and is the only reason humans have become the most genetically advanced animal to ever live.
Darwin wrote about all this. I don't know why this key discovery about who we are and where we come from is never taught.
Darwin has been used to push one political ideology or another.
Total absolute nonsense. First of all, intelligence is useful in numerous things in life, not just in war. Second of all, even amongst animals there is war - war between species and war between those in the same species for mates. So intelligence is useful in numerous situations as anyone with half a brain should understand.