The trend, starting in archaeology and spreading to anthropology reached its height in the late half of the 20th century. However, some newer research in archaeology and bioarchaeology may provide evidence that violence within 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 Keeleys 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.
Cambridge University Press; 2010 [cited October 17, 2011]. ISBN 978-0521731690. Nazaretyan, A.P. (2007). Violence and Non-Violence at Different Stages of World History: A view from the hypothesis of techno-humanitarian balance. In: History & Mathematics. Moscow: KomKniga/URSS. pp. 127–48. ISBN 978-5484010011. External links

Violence prevention at World Health Organization
Violence prevention at Centers for Disease Control and Prevention
Violence prevention at American Psychological Association
World Report on Violence Against Children Archived 2016-01-11 at the Wayback Machine at Secretary-General of the United Nations
Hidden in Plain Sight: A statistical analysis of violence against children Archived 2017-11-15 at the Wayback Machine at UNICEF
Heat and Violence