and among groups is not a recent phenomenon. According to the book "The Bioarchaeology of Violence" violence is a behavior that is found throughout human history. Lawrence H. Keeley at the University of Illinois writes in War Before Civilization that 87% of tribal societies were at war more than once per year, and that 65% of them were fighting continuously. He writes that the attrition rate of numerous close-quarter clashes, which characterize endemic warfare, produces casualty rates of up to 60%, compared to 1% of the combatants as is typical in modern warfare. "Primitive Warfare" of these small groups or tribes was driven by the basic need for sustenance and violent competition. Fry explores Keeley's argument in depth and counters that such sources erroneously focus on the ethnography of hunters and gatherers in the present, whose culture and values have been infiltrated externally by modern civilization, rather than the actual archaeological record spanning some two million years of human existence. Fry determines that all present ethnographically studied tribal societies, "by the very fact of having been described and published by anthropologists, have been irrevocably impacted by history and modern colonial nation states" and that "many have been affected by state societies for at least 5000 years." The relatively peaceful period since World War II is known as the Long Peace. The Better Angels of Our Nature Steven Pinker's 2011 book, The Better Angels of Our Nature, argued that modern society is less violent than in periods of the past, whether on the short scale of decades or long scale of centuries or millennia. Steven Pinker argues that by every possible measure, every type of violence has drastically decreased since ancient and medieval times. A few centuries ago, for example, genocide was a standard practice in all kinds of warfare and was so common that historians did not even bother to mention it. Cannibalism and slavery have been greatly reduced in the last thousand years, and capital punishment is now banned in many countries. According to Pinker, rape, murder, warfare and animal cruelty have all seen drastic declines in the 20th century. Pinker's analyses have also been criticized, concerning the statistical question of how to measure violence and whether it is in fact declining. Pinker's observation of the decline in interpersonal violence echoes the work of Norbert Elias, who attributes the decline to a "civilizing process", in which the state's monopolization