Earlier, I mentioned the “lucky latitudes” – areas neither sizzling in the tropics nor freezing in the north – which were (mostly) the zones in which foragers first turned to agriculture.
Maybe their “luck” lay in having a goldilocks climate: neither too seasonally stable (as in the tropics) nor too seasonally volatile (as in the north).
Quamrul Ashraf and Stelios Michalopoulos have looked at this issue. They conclude thus:
Farming diffused earlier across regions characterized by intermediate levels of climatic fluctuations, with those subjected to either too high or too low intertemporal variability transiting later.
Here’s a more vivid illustration of their argument:
The following thought experiment places the aforementioned effects of season-specific volatility into perspective. If the Republic of Congo’s low spring temperature volatility of 0:362 were increased to the Netherlands spring volatility of 1:453, which is in the neighborhood of the optimum, then, all else equal, agriculture would have appeared in the Republic of Congo by 5,227 Before Present (BP) instead of 3,000 BP, reducing the gap in the timing of the transition between the two countries by allowing the Republic of Congo to reap the benefits of agriculture 2,227 years earlier. At the other end of the spectrum, lowering Latvia’s high spring temperature volatility of 2:212 to that of the Netherlands would have accelerated the adoption of farming in the regions belonging to Latvia today by 1,084 years.
Yet, one anomaly appears to be New Guinea: in the tropics but with an early pristine agricultural revolution.
The basic idea is sound. Too much volatility and little new can arise amidst the turmoil. Too little and there is no reason to change one’s ways. But a “just-right” level of instability can spur experimentation and discovery.
Quamrul Ashraf and Stelios Michalopoulos (2013), Climatic Fluctuations and the Diffusion of Agriculture NBER Working Paper No. 18765