In Nature, there are neither rewards nor punishments. There are merely consequences; actions and reactions. Trees fall. Lakes dry up. Predators hunt and kill.
Only humans apply moral codes to natural actions and reactions. And, those codes are always relative to the current time, place, and power structure. Moral codes arise, fall, appear and fade away, just like clouds or ocean waves.
So, I guess, in a way, moral codes are part of nature, too.
But, sadly, most people consider their moral codes separate and external from nature, and even themselves. They consider themselves separate from nature, too; a separate “self” riding around in a bag of skin.
This, of course, isn’t the case. Our bodies, minds, ideas and feelings are all one thing. And, we can’t survive without sun, air, and water, so our bodies are one-and-the-same with nature. It’s all one thing.
The illusion of everything being separate is what causes us to crave and attach to things we wish we could later quit doing. It’s what causes relationships to stop and wars to start.
If we better align ourselves and our moral codes (regardless of their origin), with natural laws, we’ll see better progress with social justice and integration.