To my mind, it implies that there needed to be a few millennia of eating ground starches to gradually pre-adapt people to the switch-over to agriculture and surviving primarily on this strange diet. (Not saying this is a sufficient explanation though.)

The idea that the Younger Dryas millennial cold snap triggered agriculture in the Fertile Crescent is perhaps the standard hypothesis, championed by Ofer Bar-Yosef, the Dean of Fertile Crescent archaeology. Bob and I are skeptical on two grounds. First, Younger Dryas people seem to have substantially moved out of plant intensive subsistence back into more mobile hunting and gathering. That is,away from plant intensive techniques not toward more intensive versions of the Natufian and related systems. Second, most of the other primary developments of agriculture seem to have been later than the Fertile Crescent one. The Younger Dryas push hypothesis can’t be a general explanation.

The gatherer-hunter economies are pre-adapted to move into agriculture but few did. Mark Blumler argues that the pre-adapted economic system has to meet up with a pre-adapted plant species or two for cultivation to take off, specifically large seeded annual plants (or suitable tubers in some cases). California’s wild flora lacks an analog of wheat, barley, or teosinte (wild maize). The most important tubers were thumbnail sized. In California and Japan, one of the staples was acorns. They are plenty big, but not good candidates for domestication. In both California and Japan, agriculture was brought in by invaders, not adopted by natives by cultural diffusion. The speculation is that, at the margin, growing maize or rice did not look attractive to gatherer-hunters who had a system of acorns and whatever down pat. Switching to cultivation would required a lot of costly experimentation to perfect and even then might be no better or worse in terms of labor per unit food energy at prevailing population densities. On the other hand, if your target wild crop was a large seeded grass or forb, skills at handling it would already be in place and at the margin steps like deliberate sowing might have positive returns. You’ve got less of an innovation hump to get over and can proceed to agriculture one small step at a time.

The role of warfare, if any, might be fairly subtle. Gatherer-hunter California was relatively peaceful at the time of contact due, according to Bob, to specific institutions that damped down feuding and inter-tribal warfare. Polly Wiessner’s work in violence among the horticultural Enga of the New Guinea Highlands points to cycles of violence and peacemaking similar to what Peter has studied in agrarian and modern societies. I like to think that the social organizational innovations are disproportionately in the peacemaking phase of the cycle rather than in the warmaking one.

But I am still left with a few questions.

1) There still seems to be a “then a miracle occurs” moment in the progression you set forth. You arrange things thus:

1) Climate change leads to 2) intense competition between tribes which favors 3) larger tribal groups which need 4) a strong sense of social cohesion to work effectively which leads to 4) the capacity to adopt agriculture.

The problem with the sequence is that it does not explain why agriculture was adopted. It explains the necessary prerequisites to agriculture (social cohesion, complex society), and it explains why agriculture was such a useful adaptation (larger population, and by extension, larger fighting force). But we are missing the mechanism that brought this transition about.

Did hunter gatherer tribesmen realize that adopting agricultural production would raise their population over the next few generations, thus allowing them to establish martial dominance? If we asked one of these people in the midst of the transition why they were growing plants in the ground, is this what they would say?

Probably not. It is a good explanation for why agriculture succeeded after it began; it is less useful for explaining why individual communities actually made the shift.

I would submit that sedentarism plays an important role here. In North America we see large, complex hunter-gatherer societies in places of unusual resource abundance. The pacific Northwest is a great example – it has a higher biomass per square foot than anywhere else on the continent. Tribal groups in the Pacific northwest did not need to cover large areas or move around often to find game or forage. They could survive by staying put.

This leads to a few important things: increased population, the chance to build and use buildings/ritual centers, and perhaps most importantly, the chance to raise animals or domesticate plants in one place. It was probably very accidental to start out with – the seeds of what the H-G folks ate started growing next to their camps (perhaps in their waste areas?), and the H-G folks were still around when it was time for harvest. (Similar process with animals – only dogs could be domesticated before settled society arose).

2) Is there any evidence that Younger Dryas climate change affected plant communities adversely in the regions where agriculture developed? (Coming out of the ice age boosted plant productivity in the Pacific Northwest – but then again, they never had agriculture. As suggested above, they survived just fine off of the abundant forage the new landscape provided).

Makes sense i think except i don’t believe you need climate change to hit a tipping point in the level of conflict just a region where the resources available to HGs were particularly abundant thus leading to relatively high population densities. It could even be positive climate change in the sense that it *increased* resources available in certain regions leading to an increase in population and a subsequent increase in conflict and a search for a way of defusing it.

A lot of ancient priesthoods were the judges.

A region where unusually abundant resources allowed HGs to develop population densities of a similar level to agriculture sounds to me like a recipe for either a) lots of conflict and violence between different groups or b) free-riding on the surplus. Either of which (or in fact both) could give rise to a priesthood.

If so and if the priesthood created a central spot like Gobekli for group hugs then anyone who’s ever been to an open air festival without proper sanitation should be able to imagine what would happen – the seeds of wild edible plants that people brought with them to eat during the festival left behind in the latrines covering the mountain – and hence agriculture.