War is a violent form of interaction that has dominated human activity since the dawn of mankind, but to explain the ‘insanity’ of going to war against one's own species, other sciences like psychology, sociology, evolutionary biology and anthropology have contributed their views in the quest to find answers as to why we are the only mammals deliberately killing our own kind. In order to explain this ‘pathological behaviour’, evolutionary biologists have put the blame on several factors ranging from a ‘selfish gene’ most eager to replicate, to excessive amounts of testosterone directly linked to aggressiveness. Psychological explanations put forward by James as early as 1910 have suggested that warfare is as prevalent as it is because of its positive psychological effects, both on the individual and on society as a whole.

As any form of interaction between intelligent beings, war has been fluid and permutable over the two hundred millennia of our existence for which we have archaeological evidence, and over the roughly six millennia for which we have written records. Throughout recorded history, war has not developed linearly from a primitive to a more sophisticated, and hence deadlier, form of killing. As van Creveld has emphasised, there have been fluctuations in warfare but no real breakthroughs, with many factors remaining ‘unaltered well into the age of gunpowder’ or even the twentieth century. In her book on the Evolution of Strategy, Heuser refers to ‘fashions in warfare’, by which she means the prevailing attitudes in both technological aspects of war but also in strategic and tactical thinking, where she has highlighted this rather obvious, but worth emphasising, idea: