I believe based on my experience of this life that morality is hardwired into us. We don't do it for a reason; rather it is inherent to what we are. Why this should be is very hard to explain without invoking a creative force that wants it to be this way. It is also of course impossible to fathom why this same force should manifest some who behave in concert with what we all agree to be "moral" actions, while manifesting others who seemingly revel in negating any positive action they see. Our world is vastly mysterious. Any who claim to understand how this works (i.e. to be able to put an accurate framework around "life" and to predict actions/events/behaviors based on that framework) are overselling. I can see that it exists, but I make no claims to understanding how it works or why.