When we read shocking reports of soldiers posing with or desecrating the dead bodies of Taliban combatants, those actions weren't just borne of stress.

"The roots of this behaviour lie not in individual psychological disorders," says Prof. Simon Harrison of Ulster University who carried out the study funded by the Economic and Social Research Council. "But in a social history of racism and in military traditions that use hunting metaphors for war." The ESRC is the U.K.'s largest organisation for funding research on economic and social issues.

Harrison says his research shows that these actions have most often been carried out by fighters who viewed the enemy as racially different from themselves and used images of the hunt to describe their actions.

European and North American soldiers who have mutilated enemy corpses appear to have drawn racial distinctions of this sort between close and distant enemies, Harrison says. They 'fought' their close enemies, and bodies remained untouched after death, but they 'hunted' their distant enemies and such bodies became the trophies that demonstrate masculine skill.

Almost always, only enemies viewed as belonging to other races have been treated in this way, according to the study.

"This is a specifically racialized form of violence," Harrison says, "and could be considered a type of racially-motivated hate crime specific to military personnel in wartime."

Harrison gives the example of the Second World War and shows that trophy-taking was rare on the European battlefields but was relatively common in the war in the Pacific, where some Allied soldiers kept skulls of Japanese combatants as mementos or made gifts of their remains for friends back home.

The study also gives a more recent comparison: there have been incidents in Afghanistan in which NATO personnel have desecrated the dead bodies of Taliban insurgents but there is no evidence of such misconduct occurring in the conflicts of the former Yugoslavia where NATO forces were much less likely to have considered their opponents racially 'distant.'