Dear LazyWeb,

Jared Diamond makes the following claim in [his recent article on tribal blood feuds in New Guinea:

Without state government, war between local groups is chronic; co?@c3;b6;peration between local groups on projects bringing benefits to everyone—such as large-scale irrigation systems, free rights of travel, and long-distance trade—becomes much more difficult; and even the frequency of murder within a local group is higher. It's true, of course, that twentieth-century state societies, having developed potent technologies of mass killing, have broken all historical records for violent deaths. But this is because they enjoy the advantage of having by far the largest populations of potential victims in human history; the actual percentage of the population that died violently was on the average higher in traditional pre-state societies than it was even in Poland during the Second World War or Cambodia under Pol Pot.

— Jared Diamond, The New Yorker (2008-04-21): Vengeance is Ours

I don’t think that anything interesting about anarchism turns on where this factoid comes from or whether it’s true. (It’s not as if I’m suggesting personal vendetta or communal blood feud as the anarchistic replacement for state court systems. Anarchy as I understand it is an achievement for the future, not a recovery of the past.) But it is a very strong claim, which Diamond asserts without providing a citation to the source for these figures or an explanation of how they were calculated. Presumably he has a particular source, but I’m curious as to what it is.

Anyone know a likely anthropological source for this factoid, or for factoids in the general neighborhood? Help me out here.