From Chet Raymo's Science Musings blog, in an essay originally published shortly after the events of September 11, 2001:
It is as Loren Eiseley wrote: "Instability lies at the heart of the world." The criminals who wreaked havoc on New York and Washington were acting out an ancient biological script.
Yet there is ground for hope. Our brains are of sufficient complexity to give rise to that mysterious thing known as self-awareness. Our genes may predispose us to act in certain ways, good or bad, but they do not constrain us. We are effectively free to choose good over evil. Humans alone, of all the things we know about in the universe, can escape the bipolar logic of evolution.
To a cheering extent we have done so. As Margaret Mead pointed out, the circle of those whom we do not kill has steadily expanded throughout human history. The optimists among us imagine that the circle will ultimately embrace the entire planet.
From nature's point of view, there is no such thing as the Problem of Evil: order and disorder, life and death, cooperation and competition are the twin principles of nature's creative force. What humans uniquely face is the Problem of Good: How to create on this tiny planet an oasis of unalloyed peace.