DNA from human remains is showing us how different populations have evolved over time, Peter Frost explains, not only during prehistory but also well into recorded history:
This evolution has affected a wide range of mental and behavioral traits: cognitive ability, time preference, propensity for violence, monotony avoidance, rule following and empathy, among others.
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Why did the North Sea overtake the Mediterranean in international trade? Certainly, the latter region was adversely affected by the Arab conquests of the Middle East and North Africa. But the economic decline began much earlier. Shipwrecks on the bottom of the Mediterranean have been dated overwhelmingly to the time between the first century BC and the first century AD. Silver mining in Spain and Cyprus likewise fell sharply after the first century AD, as shown by lead contamination of Greenland’s ice sheet.
This decline occurred not only before the Arab conquests of the seventh and eighth centuries, but also before the barbarian invasions of the fourth and fifth and the Imperial Crisis of the third. And it seems inconsistent with modern economic thinking: bigger markets should create economies of scale, as well as a better match between supply and demand. So what caused things to go wrong?
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One cause was the low level of social trust. People trusted only their close friends and relatives, keeping everyone else at arm’s length. As a result, economic activity was bottled up within family networks, the major exception being physical marketplaces where buyer and seller could meet face to face. Because the market principle remained trapped within small pockets of space and time, it could not generalize to all transactions in Roman society. An economy of markets never evolved into a true market economy.
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One [other cause] was a deterioration of physical health, as indicated by the length of long bones belonging to over 10,000 adult men and women born between 500 BC and 750 AD. The data show a steady decrease from the second century BC, reaching a low point in the second half of the first century AD, followed by a slow recovery and then a dramatic recovery from the fifth century AD.
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The study’s authors concluded that the Romans created not only an integrated Mediterranean economy but also “the first integrated disease regime”.
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The other cause was a decrease in average cognitive ability. Fewer people could master the skills of numeracy, literacy and budgeting that are so essential to economic activity.
This decline was driven by an uncoupling of reproductive success from economic success—as I argued in a previous article. The wealthy were no longer using their wealth to bring children into the world. A rich man might prefer to leave his wife for a younger woman of low social status, often adopting her children. Or he might never marry. The resulting fall in cognitive ability can be seen in DNA retrieved from the human remains of that period.
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The North Sea and the Baltic form the core zone of certain tendencies that, for at least a millennium, have prevailed north and west of a line running from Trieste to St. Petersburg, i.e., the “Hajnal line.” These are tendencies toward individualism, the nuclear family, late marriage and solitary living, as well as a greater willingness to trust strangers and form bonds of impersonal prosociality.
Such tendencies didn’t come into being with the market economy — they arose long before for an unrelated reason. But they did provide the best behavioral conditions for a market economy once the possibility of creating one emerged.
In which context, the rest is mostly redundant.
The authors think reading is a great cognitive benchmark. It’s not a good sign.
And then it rolls into laughable quackery.
Isn’t a combination of social connections falling apart on a large scale and health problems (poor nutrition?) potentially sufficient to cause a general decline on its own?
I think the picture of Roman Empire collapsing into “Dark Age” by Kevin Crawford here can be extended backward in time, since Rome did not collapse overnight but was falling apart gradually.
https://old.reddit.com/r/SWN/comments/gtpelj/rational_behind_post_scream_inability_to_travel/fsdmnoe/?sort=old
As «giant iceberg of trade, production, social compacts, skilled personnel, and in very partial part of simple technical data» melted away little by little, this does not require completely different mechanisms for “before” and “after” it fell to pieces.
The failures increased, all sorts of things were failing. The response to immediate problems drained resources, while selection for pessimistic hedging and “turtling” strategies reduced risky investments (of all sorts) into future surplus (Taleb wrote about that part a lot). This obviously can form positive feedback loops. So all those effects draining “non-essential” capabilities only increased — until there was not enough left to keep the entire thing together, and it fell apart.