I was thinking that sustainability issues could play a part in the quantity of bloodshed evident in man's history. The obvious connection is the competition for natural resources (particularly fertile land and fresh water) which drove, at least in part, the wars of conquest. A tribe or state with desirable and poorly defended land is an easy target for an aggressor concerned with acquiring these assets. Killing the losers in this conflict relieves any necessity for feeding them or otherwise diverting resources away from the victor. At the very least, putting the vanquished to work as slaves might increase the yield of the land enough to cover the carrying costs of those extra mouths to feed.

That all seemed obvious enough, but how to explain deadly cruelty enforced against one's own people as practiced in ritual human sacrifice, especially on the scale of the early Mesoamericans. Not to excuse it, but it is understandable that a despot seeks elimination of his adversaries and potential rivals. A political prisoner is an added cost burden, a dead prisoner carries no more fixed costs with the possible exception of becoming a cause celebre through martyrdom. Something deeper is at work in the case of ritual human sacrifice. We saw the Egyptians and Chinese burying servants or slaves to accompany their dead leaders in their afterlife journeys. Implicit in this practice is the fact that there was a surplus of available bodies to fill this duty call. If human life were dearer, not only in a sentimental manner but in terms of the survival value for society at large we would likely see much less cavalier dismissal of living humans.

As an offering to "the gods," human sacrifice has at least a(n) (arguably faulty) logical basis. Then the question becomes "how much sacrifice is needed to achieve the goal," the goal being a good harvest, victory in battle, whatever the cause du jure may be. Once power is in the hands of the priest class, whether through the merging of political ends with the ends of priest-craft, or through some sort of collective mindset which provides a positive feedback loop reinforcing the perceived rightness of such courses of action we see the institutionalization and expansion of killing.

It was interesting to consider the seminal thinkers in light of this topic. While they were outwardly linked by connection to subsequent religious movements (or more properly a philosophical movement in the case of Socrates) there is one of them which jumps out at me as an exception. "The Prophet" Mohammed was not only involved in proselytizing, he was quite militant about it. Some of the other major religions feature lesser degrees of proselytizing but Islam as promoted by Mohammed himself was a major turning point in the function of war itself. No longer was conquest solely about the rivalry for food and water (which in turn led to considerations of power and security) but conquest in the name of religion was introduced. The rationale for war expanded from the arguable rational (at least inasmuch as a logical case can be built in support of) to the irrational, understood in this context to mean the province of faith, of the zealot and not strictly comprehensible prima facie.