I have taken this insight as the starting point of the anthropology upon which I based my theology. Rather than starting from the position that human beings are essentially good, or human beings are essentially evil, I try to start from the point that human beings are essentially small group animals, with all the virtues and vices of small group animals. What seems to us to be best about human beings: cooperation, altruism, self-sacrifice, capacity for love, compassion are all the emotional qualities that exist within the small band. What we see as human cruelty is what is often the qualities we show to the outsiders of our small band: violence, suspicion, intolerance, murder, predatory rape.
Human beings also show a persistent tendency to create ever more complex systems and structures to avoid deadly conflict. My guess is that the development of marriage was for the purpose of avoiding the endless conflict between males for social dominance and sexual access to females. (Why am I suddenly thinking back to high school days now? But, I digress.) That it also made patriarchical inheritence of surplus wealth possible is an added bonus, h/t to Frederich Engels.
So the creation of systems to avoid conflict has created a larger and larger human community and culture, which is in conflict with our hard-wired small group loyalty. Hence most of our moral issues pit some form of "widening the circle" against some from of "smaller group loyalty".
Our biological evolution was driven by survival and brought us so far. Human beings, on a biological basis have not changed significantly in tens of thousands of years. Our cultural evolution is driven by the desire to accumulate surplus wealth and to avoid conflict, and moves very quickly. Culturally, we are very different than we were 100 years ago, much less 5000 years ago.
Religion, Philosophy and spirituality are the venues in which humanity tries to consciously grasp the meaning of our common evolution and to shape the cultural evolution that is occurring today. It is bigger than science, since it deals with the meanings we draw from reality and the moral conclusions that we draw about our actual nature, and the possibilities that humanity sees for itself.