The world is an arena.
Survival of the fittest is still going on, but not in the way that you might expect.
When we were still going at it with sticks and stones, chasing after our food, only the groups that had the strongest humans would be able to survive. If you couldn't catch your food, you had to find other creative ways of surviving, such as providing a good or service to the strong group in exchange for food.
That marks the beginning of any societal structure - the moment that one human depends on another for something crucial to their survival. As the society grows bigger, the person one hop away from the food producer will have someone dependent on his goods or services - his skills in other areas of life-improvement developed because he left the food catching to someone else.
Today, everyone is working for each other - providing specialized outputs that others cannot obtain for themselves.
Go on long enough, and you have what we have today. Each one of us depends on so many hundreds of people all doing things that we have chosen to pay for instead of do ourselves, and we need to specialize in something so we can keep providing goods and services that others depend on. And because each of our specializations are focused on improving things for other people, everything is just getting better and better as time goes on.
Wait, but why are we still bombing people?
Because the original human that people started depending on for sustinence had a territorial dispute with the other original human and it's still going on.
If you go back far enough, you'll probably find that it's the dumbing thing in the world, like one guy stole another's femaale, and if everybody found out that they have been sacrificing their and other's lives for that, they'd go twist the neck off the guy's descendent.
Well, today survival of the fittest means something different. We're now in a phase of forced contraction instead of expansion. There's a bunch of stuff that people do and produce that are not going to be needed at some point. What do you do with all of the people with a specialization that stopped being so special?
The government will provide for them? Raise minimum wage?
Yes, until they become a burden. Then what?
It's anyone's guess.
A lot of people died from the flu this season, see if you can figure out why.