The Issue of Atheism

First, I want to humbly say I have not solved the problem.  I only want to make this observation.  From where to modern atheists derive morality?  If humanity is involved in evolution and a part of evolution is the rise and fall of species, the demise of homo sapiens sapiens at the hands of our own environmental destruction could be perceived as an evolutionary dead end.  We evolved the ability to kill ourselves, and we did (or we are).  If our species dies because of this, there is nothing wrong with that.  We, technically speaking, should die.  Still, many evolutionary biologists believe, morally, the destruction of the environment is bad.  Why?  Where did they get the notion that peoples should decide whether or not they fatally destroy themselves if their self-destruction is evolved?  I just want to know.  Is our belief to protect ourselves from ourselves a simple survival strategy?  If so, why would we evolve the capability to crush ourselves in the first place?  I have many questions that no atheists have answered yet.  Peace!