"The student of biology is often struck with the feeling that historians, when dealing with the rise and fall of nations, do not generally view the phenomena from a sufficiently high biological standpoint. To me, at least, they seem to attach too much importance to individual rulers and soldiers, and to particular wars, policies, religions, and customs; while at the same time they make little attempt to extract the fundamental causes of national success or failure."

Next Quote

Today the human race is a single twig on the tree of life, a single species on a single planet. Our condition can thus only be described as extremely fragile, endangered by forces of nature currently beyond our control, our own mistakes, and other branches of the wildly blossoming tree itself. Looked at this way, we can then pose the question of the future of humanity on Earth, in the solar system, and in the galaxy from the standpoint of both evolutionary biology and human nature. The conclusion is straightforward: Our choice is to grow, branch, spread and develop, or stagnate and die.

— Robert Zubrin