This chapter investigates the common themes, which develop with regards to these causes of violence and try to relate these findings back to the discussion in MSW. It provides more evidence for the arguments laid out above. In particular, it will start with an analysis of human nature, an analysis of the causes of war at the first image, the first level of analysis. Human aggression therefore is usually not purely instrumental, which the Realist discussion on the causes of violence and human nature suggests. The most interesting branch of study, and the one which probably put most effort into the analysis of violence as aggression, is the discipline of psychology. Sociobiology is a fairly young discipline, which originated in 1975 with E. O. Wilson's monograph Sociobiology: The New Synthesis. Anthropologists have long maintained that man is essentially a peaceful animal and that war is an invention and depended on cultural evolution.