The skeletons of Jebel Sahaba are not telling us that we are capable of killing our own kind. Everybody knows that, and it's a skill that we share with our near relatives, the chimpanzees, and a number of other species. Nor are they just telling us that we are capable of highly organised mass killing. All of our recorded history is filled with war.
What the graves of Jebel Sahaba are really telling us is that civilisation was not the problem - and perhaps also that we are not doomed to perpetual war.
Anthropologist Raymond Kelly studies warfare among pre-civilised groups, and in his book Peaceful Societies and the Origins of War he offers us three eras.
In the first period, our hominid ancestors behaved like chimpanzees still do. If a foraging party came across a member of a neighbouring group near the borders of their territory, they would kill him if it was safe to do so - in practice, if they outnumbered him by at least three-to-one.
This behaviour had a cost, however, because it made the borders dangerous: chimpanzees typically spend three-quarters of their time in the central third of their territory, and all the rest is under-exploited. So human behaviour changed when the development of weapons that can kill at a distance (spear-throwers, slings, bows and arrows) made the outcome of any attack more uncertain.
In this second period, starting around 400,000 years ago, Kelly argues that intergroup violence fell sharply. Neighbouring human groups, made up mainly of nuclear families, worked hard at being neighbourly. At times of seasonal abundance they would even come together to socialise, trade, court spouses and perform shared rituals.
This fostered trust and peace - and they got to exploit all of their territory.
The last transformation was driven not by technological change but by the rise of what Kelly calls "segmental societies" - ones where nuclear families became associated in larger clans that extended down the generations. This allowed them to mobilise large numbers of warriors for purposeful raiding.
War becomes institutionalised in human societies, and grows as they do.
Welcome to the present, you might say. We all still keep armies, and they are constantly preparing for wars that may no longer even involve land. But have you noticed that no great power has fought any other for the past 69 years? That is quite new in our history.
The second transformation, the one that led to about 400,000 years of relative peace, occurred because attacking your neighbours had become too dangerous: the weapons had got too lethal. It is possible that we are in the midst of a comparable transformation now, although it must be admitted that there is still rather a lot of the old behaviour around.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.