Philosophers and Theologians have come down on both sides of the argument. Economists have also given us theories of Capitalism that describe the system as a channeling of the worst trait of humans: greed.
I think what is important in this discussion for our purposes is realizing the effects of this argument on our theories about Reptilians. If we believe that human beings are essentially evil, or capable of great evils, then much of the Reptilian theory can be dismissed. Why would we need Reptilians to explain tragedy and oppression if humans are perfectly capable mass murderers?
Yet modern research has shown that living organisms often do better when they cooperate and work in a harmonious system. Ecologist Gregory Bateson wrote that Darwin's mistake was focusing on competitive survival, while the truly valuable trait for creatures to have is a sense of flexible organization within their environment (see Form, Substance, and Difference by Bateson). Humans are also capable of great amounts of empathy in normal circumstances.
In stressful circumstances, however, this can change. In these cases, a human being relies heavily on the part of the brain known as the "reptilian" brain, which, according to neuroscientist Paul MacLean is an ancient foundation of the modern brain. This part of the brain is the most basic, limited to controlling vital functions and simple instincts such as self-preservation. In some stressful incidents, human beings are capable of great feats of strength and sometimes, regrettable violent episodes.
But is it possible to explain away organized evil and democide (as R.J. Rummel termed state-sponsored murder) with concepts of self-preservation or instinctual reaction? I think not. The holocausts of states are methodical and planned. As a human being I would not , for reasons of decency and rationality, destroy or hinder the life of another. Humans are no doubt fallible, and for this reason, no person or group could consistently provide a society with positive security. Indeed, how can we reasonable allow the very existence of states when we believe that no person should hold unlimited and violent power over another. Clearly there is Something at work in our world trying to grasp and maintain power--Something that is willing to use inhuman means in its insidious quest.