<Snipped quote by DarkwolfX37>
I'm actually curious about your answer, since you won't derive it from biblical beliefs--mine is based on the biblical idea that man has a fallen nature.
It's a bit roundabout when I say it so bear with me. The long story short is that we developed empathy along the way, we don't like pain, so it's a useful tool against things that feel pain that we don't like.
It helped us survive. Humans don't have claws, or sharp teeth, or high speed, or high jumping ability, or tusks, tough skin, etc. that other species have to keep them alive. We've got tools and a "more advanced brain" that spawned them. We respond to pain, like any mammal does, and we're a social species that builds tight-knit groups, tribes, societies, so on. If someone who has better tools than you gets food, and you don't get any, you'll starve. If you're starving, you'll want to kill to survive. If you're not getting much food or mates because you aren't high socially, you'll aim that intent at those in charge, rather than at prey. Because we respond to pain, inflicting pain to subjugate others is the obvious action to take to get more people to obey you. Our drive to survive and breed leads to fighting within our own tribe, and our instinct that anything different is dangerous leads to fighting between tribes. Because this helped us survive and later thrive, it was never bred out of us. So as time went on and we gained communication, we gained more ability to inflict pain to other things, because now we can more effectively organize our own group to work together against prey or other groups. We respond to pain, so we could use our group to subjugate another group, increasing the size of our own. Then the fighting moves back to within, because everyone wants the highest status to get the most mates. With language came ideas, then ideals, and suddenly motives changed but the method still works. Someone with a different language comes, we can't communicate, they're different and we don't understand them therefor they're dangerous, so kill or wound them. More time goes and our tribes get bigger, we need more resources, competition with other tribes grows. Suddenly you have nations and wars. From there, survivors pass on their tensions to their offspring, and you get revenge added onto distrust of the unknown. Skip to today, we have this same tension between skin shades, between cultures, between ideas... Instead of breeding out hatred of the new to us, we bred it in deeper because it worked for us. Now we're outside of huge chunks of natural selection so we don't need it very much anymore, but it's still there in our instincts, and generations don't try to raise it out of their offspring, so it keeps growing and stagnates at the status quo.
Bing bang boom we're violent towards each other and have no outside threats to direct it towards instead, and we don't educate everyone to a high enough degree which furthers the differences and the instinctual distrust that comes with them, we don't recognize the outside threats we create, and so we just sit here trying to beat the shit out of each other.
Long diatribe that basically boils down to "it helped us when we were a young species, on an individual and group level, so those with the violent approaches bred well and those without didn't, and now nearly everyone has it and doesn't try to raise it out, so there's no counterbalance to the nature from the nurture, leading to fighting.
