Morals are a intellectual shortcuts designed to help circumvent our natural proclivity for short term thinking over of long term thinking. As such, they change to some degree depending on the culture and society they arise in, to better suit the long (or medium, depending on your scale) goals of that society. Ancient Mongols were not immoral, fist differently moral than many of their contemporaries (and probably not as much as you would think), but that propelled them to the apex of human nations (based on what that meant at the time) for a while.

>>Nature by default doesn't have nuclear weapons....

While I agree with your sentiment, just would like to point this out that nature does have nuclear weapons, pretty scary ones for that matter: the stars.

Also, if we take these things to their logical conclusion, then the nuclear weapons created by human beings are, of course, created by nature - in this case, indirectly, using the humans.

This is just to point out the logical aspects of the arguments. Other than that, I do agree with you that we, the humans, need morals to sustain a better life for most human beings.

It seems pretty common among social animals, violators get cut from the herd or monkey stomped.