Sociologists and historians often view dehumanization as central to some or all types of wars. Governments sometimes present "enemy" civilians or soldiers as less than human so that voters will be more likely to support a war they may otherwise consider mass murder. Dictatorships use the same process to prevent opposition by citizens. Such efforts often depend on preexisting racist, sectarian or otherwise biased beliefs, which governments play upon through various types of media, presenting "enemies" as barbaric, undeserving of rights, and a threat to the nation. Alternately, states sometimes present the enemy government or way of life as barbaric and its citizens as childlike and incapable of managing their own affairs. Such arguments have been used as a pretext for colonialism.
The Holocaust of World War II and the Rwandan Genocide have both been cited as atrocities predicated upon government-organized campaigns of dehumanization, while crimes like lynching (especially in the United States) are often thought of as the result of popular bigotry and government apathy. The main cause behind the American mutilation of Japanese war dead has been stated to be dehumanization.
Anthropologists Ashley Montagu and Floyd Matson famously wrote that dehumanization might well be considered "the fifth horseman of the apocalypse" because of the inestimable damage it has dealt to society. When people become things, the logic follows, they become dispensable - and any atrocity can be justified.
Dehumanization can be seen outside of overtly violent conflicts, as in political debates where opponents are presented as collectively stupid or inherently evil. Such "good-versus-evil" claims help end substantive debate. (See also thought-terminating cliché).
The Darwin Awards are considered by some to be dehumanization as entertainment. The death or sterilization of Darwin Awards honorees is celebrated because they have removed their un-fit genes from the human gene pool. Others think the Darwin Awards are merely funny, without involving dehumanization. Other forms of planned circus of past eras, such as the man-to-man mortal combat gladiatorial events of the Roman Colosseum, are more clearly dehumanizing since a human life is exchanged for entertainment.
The dissections of human cadavers, such as in these videos was seen as dehumanizing in the Dark Ages (See Medieval anatomy), but now the benefits of well-trained physicians are more clearly understood.