Here’s what I see going on with polarization since the human career began. The orthodoxy has it that the Neolithic Revolution and the Industrial Revolution demarcate stadial social evolution. Both the Neolithic Revolution and the Industrial Revolution are either overrated or misdated. The former is dated to ten or twelve centuries before Christ and said to last until the birth of civilization; the latter to 1760-1830 Britain. If we buy the anthropometric evidence, the second is bunk. There is also good reason to believe that Andrew Sheratt is right on the money so that what really mattered in the former case was not the Neolithic Revolution but the Secondary Products Revolution which began at Uruk and spread out from there between 4000 and 3000 BCE.
What the anthropometric evidence points to is that the premodern pattern prevailed until the late-nineteenth century. Indeed, it was not until the mid-century passage, 1920-1960, that the hockey stick is hit in earnest. I want to argue that it was the Second Industrial Revolution, 1860-1960, that made the hockey stick in living standards possible in the temperate zone; that it was the Secondary Industrial Revolution that repealed the Malthusian law; just as Sheratt’s Secondary Products revolution made Uruk the first central (and then the only existing) power. The issue is that there were indeed two general revolutions in the material possibility frontier. These were the secondary revolutions that revolutionized the value of generalized domestications in the first case and in the second case, generalized industrial production with fossil fuel-powered machinery in agriculture, industry, and transport, thus revolutionizing the thermodynamic basis of civilization.
There is indeed some truth to the stadial frame. The secondary revolutions made possible hitherto unimaginable living standards. In the first case, this began at Uruk sometime during the Ubaid period. From there on Babylonia was a part of the Central Civilization—the longest continuously urbanized macro-region is the zone at the intersection of Europe, Africa, and Asia. This is of course no coincidence. What happened in Babylonia is that a major climate shock made the lower Euphrates extraordinarily fertile. At Uruk in the fourth millennium BCE, agricultural yields, pottery manufacturing, metallurgy took off; they invented writing, administration, the potter’s wheel, the plow and the wagon; domesticated oxen for traction, cattle for milk products, and the donkey for transport; and mastered micro-domestication (leavened bread, cheese, beer and wine). The ‘early high civilization’ is an extraordinary case of polarization. The Sumerians played an extraordinary role as the founders of the Central Civilization when they had the field to themselves in the fourth millenium BCE. It was the transmission of Babylonian wagon technology at the very edge of the Uruk world-system, the steppe (southern Russia) that triggered the very formation of the Yamanaya (Proto-Indo European speakers). The wagon allowed the Yamanaya to tame the steppe since they could exploit the otherwise meager open steppe by near constant movement, as David Antony has argued so forcefully. In the history of the peopling of the world by west eurasians, Uruk thus plays the dramatic role usually assigned to alien civilizations in fiction.
The Secondary Industrial Revolution identified by Gordon as the Second Industrial Revolution, 1870-1970, made both living standards and war potential higher than hitherto imagined. (See the evidence from stature.) More generally, the evidence from anthropometry cannot be reconciled with the orthodox narrative. Let’s not forget that the hockey stick adds a dynamic element to the global condition. Interestingly, latitude is not priced in c. 1880. Far from being a “constant,” latitude’s influence was weak in the premodern era when stature was a function of the local availability of protein. It is the hockey stick that radically polarizes the world in terms of living standards. Latitude itself has a history that has yet to be told. But then so do both the secondary revolutions.
Any credible deep history of human welfare must put the secondary revolutions at the center of the narrative frame.