Skulls for the Skull Throne!

There have recently been discussions on Mesoamerican civilizations prior to the Spanish incursions on this blog, in light of the recently unearthed racks of thousands of skulls sacrificed in honor of the blood gods.

Interesting fact about Tenochtitlan, capital of the Aztec Empire: With a population of 250,000 in 1519, the only demographically comparable European city at the time was Paris.

What made this especially impressive, though, was that Mesoamerica was, strictly speaking, still in the Stone Age. Nor was Tenochtitlan some freak occurrence: In 500 AD, Teotihuacán — which the Aztecs claimed descent from — had a population of 125,000, just one millennium after the appearance of cities in that region. The first Eurasian cities to reach that size were either Nineveh (~700 BC) or Babylon (~500 BC). And if we are to take the Eurasian technological period most analogous to the late Aztec Empire — the cusp of the Bronze Age around 3500 BC — then the largest city then was Uruk, which had a mere 20,000 or so c.3500 BC. Tenochtitlan was almost an order of magnitude more populous than the largest Eurasian city at its equivalent point of technological development.

Although crop cultivation in the Americas began almost coterminously with East Asia, if a couple of millennia behind the Near East, the staple crops took a great deal longer to get domesticated.

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The Americans were hampered by a poorer natural resources endowment (e.g. much fewer animals that could be domesticated), and a lack of east-west “tilted axes”, which precluded information and technological exchange across a wide swathe of different civilizations. {snip} Mesoamerica and the Andes civilizations would have eventually developed oceanic transport, and cut out the impassable tropical areas in between. Civilization would also have spread north to the (higher IQ) American Indians; the economic and innovation center of gravity would have kept going north, just as in the Old World it crept north and west with each passing millennium.

Meanwhile, what is mentioned far less is that the Americas also had some major advantages. First, no horses might mean much less horsepower, but it also means no nomad raiders harrying civilization whenever there’s a failed harvest, dynastic dispute, or steppe drying event. Second, corn and potatoes are much more calorie dense crops than their Old World equivalents (wheat, barley, various roots and tubers). Finally, no horses or other powerful draft animals also meant no land set aside for grazing, resulting in higher total caloric output (at equivalent tech levels), much higher population densities, and hence much larger cities. Finally, no tilted axis also means much less parasite load, even adjusting for general development, since vast areas would not trade exotic diseases with each other. Diseases overwhelmingly strike the cities, and are dysgenic, since they don’t differentiate between rich and poor (though the really rich could escape to their country retreats, like the heroes of the Decameron). Since cities have always been the main rotors of scientific and technological progress, this means that the early American civilizations simply had far more potential “innovators” as a share of their population relative to their tech-equalized Eurasian counterparts. {snip}

Commenter reiner Tor suggests that these ecological factors also explained the superlative scale of human sacrifice in the Aztec Empire:

Human sacrifice was probably also a function of primitive savages suddenly achieving relatively high levels of organization and population density. Primitive savages everywhere were, well, primitive savages, cannibalism was widespread in Europe, for example. But they only had small-scale organizations, so even though Europeans a few tens of millennia ago were all cannibals, they didn’t have the organization to capture and kill so many slaves.

There is the explanation that a lack of domesticated animals meant that human meat was an important part of elite diets (while the rest of the population suffered from a dearth of vital amino acids). I just checked Wikipedia, and didn’t find the counter-arguments terribly convincing. Yes, people could eat salamanders, but it’s difficult to extract a lot of meat from them, while human meat is much easier to consume.

However, the fast rate of technological growth might have meant that sacrifice was not due to survive much longer in that region of the world. {snip} By extension, large-scale human sacrifice may only have had a millennium left in Mesoamerica c.1519 even if Eurasia was wiped out by a gamma ray burst before Cortes set sail.

Then again, the mega-empires of the Axial Age were enabled by… cavalry armies. These armies were created to defend those empires from the nomads, as Peter Turchin argues in Ultrasociety. But no horses in the Americas. And reiner Tor makes the grisly observation that the elites would have still needed their literal pound of flesh. Maybe the Aztec Chaos cults would have been self-sustaining for much longer?