What Malthusian catastrophe reverts to middle ages?

December 30, 2016 5:47 AM

To be clear, what population decimation (50%, 80%?) drives our (western) world back to the middle ages, despite our accumulated/combined knowledge (and how)? Assume global event - I can't imagine one developed nation devolving unless all have
posted by b33j to Science & Nature (24 answers total)

A repeat of the 1859 Carrington Event could set things on the way by erasing a great deal of the accumulated/combined knowledge.
posted by chimpsonfilm at 5:54 AM on December 30, 2016 [1 favorite]

I think really really high. A huge portion of our population consists of MDs, PhDs, and engineers. Even if 99% of people in the US die, whatever thug takes power is going to want electricity. And antibiotics. We have way more people than we need to maintain civilization, including moderate advancements. That still leaves 3 million people in the US. Maybe at under 300,000 we'd have a limited knowledge/skill base.
posted by Kalmya at 5:58 AM on December 30, 2016 [4 favorites]

Back to the middle ages in what sense? It's not obvious how simple population loss would lead to food shortages.
posted by jon1270 at 6:11 AM on December 30, 2016

It's kind of comparing apples to oranges because Malthus just didn't have a lot of the knowledge we have now. So one can't accurately apply his theory of population decimation to current society. It would be pure conjecture. His big theory circled around unchecked population growth but was based on facts known in 1779 so it's hard to recalculate this based on a Malthusian Catastrophe Model. But it's definitely food for thought as far as population, etc.

The answer is tricky because we now know things Malthus didn't. We definitely know that were consuming a lot if not too much, decimating ecosystems, etc. -- all stuff Malthus never considered, but we also now know more things.

I stole this from Wikipedia: A 2004 study by a group of prominent economists and ecologists, including Kenneth Arrow and Paul Ehrlich suggests that the central concerns regarding sustainability have shifted from population growth to the consumption/savings ratio, due to shifts in population growth rates since the 1970s. Empirical estimates show that public policy (taxes or the establishment of more complete property rights) can promote more efficient consumption and investment that are sustainable in an ecological sense; that is, given the current (relatively low) population growth rate, the Malthusian catastrophe can be avoided by either a shift in consumer preferences or public policy that induces a similar shift.
posted by yes I said yes I will Yes at 6:12 AM on December 30, 2016 [1 favorite]

Not an answer to your question, but you may be interested in a novel I just happened to read a couple of weeks ago.

Earth Abides (1949) opens shortly after an unknown disease has wiped out most (not specified, but appears to be >99%) of the human population. The main character, Ish, attempts to pass on "civilization" to the children born into his small group, but eventually abandons his little school room, which the children didn't particularly like anyway, in favor of more natural learning experiences re the world around them. By the end of his life (and the novel), it's clear that the old civilization is gone. The survivors may attempt to use leftover relics, e.g., they have guns, but the bullets are deteriorating/not reliable, so they hunt with bows and arrows, but it appears that literature, science, etc are gone. People live among the ruins of the former civilization as if they're simply part of the natural environment.
posted by she's not there at 6:16 AM on December 30, 2016 [2 favorites]

Of course, a lot will depend upon the state of the infrastructure. E.g., if communication systems are damaged or destroyed, those 3 million survivors referred to above may take years to find each other. In the meantime, other systems will be deteriorating, e.g., meds will be expiring.
posted by she's not there at 6:24 AM on December 30, 2016 [1 favorite]

Best answer: This research paper presents a model of civilization growth and decline in terms of four parameters: natural resources, stored wealth, commoner population, and elite population.

It doesn't present numbers related to the real world (the ratios of these numbers are what are important), so it doesn't directly answer your question. However, it would suggest that a loss of population doesn't directly cause a catastrophic collapse: what's more important is where those losses are concentrated (commoners vs. elites) and are due to a collapse of what resources (natural resources vs. commoner labor vs. stored wealth). In some cases, everything bounces right back; in others, there's a systemic collapse.
posted by ragtag at 6:29 AM on December 30, 2016 [2 favorites]

I'm not sure there is, because even if the population was reduced to a few thousand, you'd still have millions of physical references (engines, tools, etc) to help your education to jump ahead of Middle Age tech in pretty short order.

So, you'd be looking for an event that would destroy the reference materials.

A nano-bot devised to help with nigh-perfect recycling in an overpopulated world seems like a useful thing, but it had a bug and got wild. It starts breaking down metals and plastics into little piles of raw material and eats the modern world.

Vehicles, power-stations, wind-farms and solar would crumble to dust, the very pipelines that carry our oil and gas would disappear, even the cans and bottles in the supermarket would dissolve spilling and spoiling their contents across the shelves. Buildings would crumble as their rebar, bolts, and nails turned to dust, causing the destruction of the majority of paper-references on modern technology, keeping us locked in a time even before the Middle Ages.
posted by Static Vagabond at 6:43 AM on December 30, 2016 [10 favorites]

I don't see that mere drop in population would do it. Black Death cut Europe's population something fierce in the years 1346-53, but for the survivors, things actually started improving. Within a hundred years, we're talking the Renaissance.
posted by BWA at 6:44 AM on December 30, 2016 [8 favorites]

You can't just look at deaths; you have to look at how resilient is the population, its capacity to suddenly start living differently, take advantage of chaos, etc. Collapse would be caused by trying to maintain something expensive that becomes even more expensive, leading to regular people opting out of our civilization and not having another nice place to go. There are historical examples of this.
posted by michaelh at 7:22 AM on December 30, 2016

I don't think a population drop short of 90% would do it. If you look at history, advanced societies do quite well at handling natural disasters and wars that wipe out huge fractions of their populations. It's when the institutions collapse due to economic issues or bad leadership that societies fail. You might enjoy Collapse by Jared Diamond.
posted by miyabo at 7:25 AM on December 30, 2016 [1 favorite]

For the most part, dramatic population loss historically raises the standard of living for the next generation of survivors. Plague and famine decrease the number of mouths to feed in the next few cycles, while boom years increase the population such that it outstrips the available resources. Even if you disagree with his eventual conclusion, I highly recommend Gregory Clark's A Farewell To Alms for a fantastic look at the cycles of civilizations as they bumped up against the Malthusian limits (essentially, up until the industrial revolution).

The industrial revolution also happened with relatively isolated pockets, yes, there were resources moving globally, but those resources took ages to travel. So even if we went back to the population levels of the earlier 1800s, say 15% of what we have today, if energy was relatively cheap per capita it's likely that decent sized population pockets could maintain that level of existence, or probably quite a bit higher (ie: Without markets necessary to support multi-billion dollar semiconductor fab labs you don't get modern computing, but with some level of global trade you can probably get 1970s level computing, microcomputer fortunes used to be made on markets of a few tens of thousands).

With no particular statement about how that level of existence gets distributed across the populace.

So, yes: the real question is how the social institutions distribute the wealth. It's fairly easy to imagine going back to a few royal families and large swaths of people living essentially under feudalism, because we aren't terribly far from that in parts of the rural United States. Dirt floors and share cropping aren't that far in the past, and economic systems and social norms that enforce that rise and fall all the time.
posted by straw at 8:29 AM on December 30, 2016 [3 favorites]

I think it will be a charismatic, schizophrenic tyrant coming on the scene at the same time that the first singularity is about to become a reality. Working in tandem at first, the tyrant would reduce larger and larger swaths of the population while the government backed singularity is chugging away to “help” solve the tyrant’s “problems”. Then, at some point, there’d be a paradigm shift where the tyrant’s usefulness to the singularity (and its future versions) no longer seemed logical and the tyrant and his cronies would be over-written. From there, what ever was left of the human population will be managed by the singularity- like live stock.


Sad thing is, if you look at our tech trajectory, there is no way to avoid this future where the singularity is concerned, it is going to happen. Whether it be in the USA, China or Russia, it is going to happen and our ability to control its influence will be very short lived.
posted by bkeene12 at 8:56 AM on December 30, 2016

One of the things to consider is the speed of the population cull. There are all sorts of things that can be pretty dangerous long term if not shut down properly (think nuclear power and chemical plants but also things like dams). An event that culls a 1/3rd of the population in a couple weeks will also bring ecological disaster verse a slow decline over a couple of decades.
posted by Mitheral at 9:27 AM on December 30, 2016

Population decline or deaths because of plague dont normally result in civilization-level collapse except for consequences due to after-effects. France faced a 14th century famine followed by the Black Plague followed by the 100 years war, but France did not cease to be France from a development and cultural point of view.

Civilization-level collapses due to population decline occur either because the decline is extreme-- as in the Native American tribes and civilizations that lost 90-95% of their population to disease, or because population loss allows another civilization to fill in the vacuum that disrupts existing social networks that allows civilization to flourish. Depopulation of the Roman/Byzantine Empire due to plague in the 6th and 7th century made it impossible to field sufficiently large armies to defend the empire and absorb and military defeats. As a consequence, the Muslim takeover of Egypt and North Africa interrupted trade between the Mediterranean and Western Europe, which meant there was no longer any papyrus available or connections between what remained of the Roman civilization. This ends up causing a collapse in both knowledge and resources.

Enough specialists responsible for holding civilization together need to die (for example, in the Bronze Age, these would have been the scribes, who were a bottleneck when it came to literacy, which is how complex trade transactions were maintained), combined with isolation due to collapsed trade networks because there wasn't enough of a population to maintain them. The remnant population then reverts to the level of those they CAN trade and communicate with.
posted by deanc at 9:30 AM on December 30, 2016 [1 favorite]

I think the novel "Soft Apocalypse" explores this concept well. The upshot is that some foreign power EMPs most of the country by setting off a few nukes in the upper atmosphere. As a result, just about every non-hardened object with a circuit board stops working. No electricity, no refrigeration, no cars newer than a certain year, no medical facilities...the bottom line is that it gets ugly fast. The statistic mentioned in the book is that the US can support about 30 million people with its existing natural resources, so one sees the difficulty immediately. And yeah, it can happen to an individual country without affecting other developed nations.
posted by Autumnheart at 10:39 AM on December 30, 2016 [2 favorites]

I think the answer is that, depending what you mean by medieval, no amount of population loss is going to reduce civilization to that level for the simple reason that a great many of the technologies that made medieval life possible are truly lost, superseded by more modern techniques.

More ancient technologies are academic or hobbies and not widely known. I can all but guarantee that there are at least as many people who can make black powder and bullets from raw materials as people who can make an arrow that flies straight. It's easier to find an engineer and a machinist who could scavenge and build the tools necessary to equip a machine shop than it is to find someone who can blacksmith or even flint knap with any skill.

If enough people are wiped out to take out technological civilization, we aren't back to the medieval ages, we're back to the pre-paleolithic. "Primitive" technological skills are actually rarer in the modern world, and therefore easier to lose.
posted by Zalzidrax at 10:49 AM on December 30, 2016 [6 favorites]

The book A Canticle for Liebowitz is set in this kind of future. While a nuclear war kicks things off, what really changes the world is the Simplification: the survivors blame technology for the Flame Deluge and intentionally destroy all remaining modern tech. I'd guess that sort of thing would be a few true believers and a bunch of people caught up in the frenzy who all felt pretty dumb when winter rolled around and they starved to death.

So it could happen that the medieval part comes first, and the death part comes second.
posted by BeeDo at 11:57 AM on December 30, 2016 [1 favorite]

I don't think it's population loss that does it, it's a major disruption to the social contract. Anything that puts society into a "don't trust anyone, everyone out for themselves" mode hard enough does it. People who are worried about food, shelter, and security are not mining lithium for iPhone batteries. A small cult of neighbors is not running a nuclear power plant.
posted by ctmf at 12:02 PM on December 30, 2016 [2 favorites]

Response by poster: Oooh, this is amazingly helpful for getting down to the nitty gritty details of my plot. I think the issue I need to consider is economies of scale - when you have many people, you can specialise in almost infinite ways. With a significantly reduced population, each individual must be more generalist (as each industry must). For example, farmers couldn't grow just cucumbers anymore - the distribution system to deliver them to a wide market wouldn't exist - they would have to grow multiple crops. Doctors would need to practice more general medicine, and so on. I think.
posted by b33j at 2:09 PM on December 30, 2016

If anything disrupts the infrastructure needed to fix nitrogen and distribute fertilizer, then maybe 40% to 75% of the earth's population stops getting fed. Unless the problem could be fixed quickly it would be irrelevant how many people knew how to restart the process. That's only going back to the early 20th century.
posted by rdr at 4:47 PM on December 30, 2016 [1 favorite]

You might find this Wikipedia article on nuclear winter interesting. From the article:

A minor nuclear war with each country using 50 Hiroshima-sized atom bombs as airbursts on urban areas could produce climate change unprecedented in recorded human history. A nuclear war between the United States and Russia today could produce nuclear winter, with temperatures plunging below freezing in the summer in major agricultural regions, threatening the food supply for most of the planet.

Here a take on Feeding Everyone No Matter What.


If such catastrophic events were to occur at a global (or even hemispheric levels), it would not be very difficult to speculate that if anyone were to survive, it probably won't be in urban areas, but rather in pockets here and there, where technology currently penetrates rather unevenly (and no much actual knoweldge is to be found) and medical care is also not the best. In that situation, it is also not difficult to imagine some sort of pre-modern societies (in terms of both skills, technology, and obviously social organisation) being what survives.

In one of the threads here (possibly one of the election threads) people also mentioned that if nuclear war is to be our lot in the future, the southern hemisphere might be less affected (at least not affected by the immediate fall-out, since there are fewer likely targets). I assume that any nuclear winter modelling would have the effects be global, but there might be less affected regions somewhere in the southern hemisphere?

Alternatively, some more arcane or technology-based non-sunlight solutions to the feeding problem might be imagined in more urban areas that are not direct targets. I keep imagining something like electricity-based aquaponics, with the electricity being produced by water, or by some poor donkey going round-and-round...
posted by miorita at 6:22 PM on December 30, 2016 [1 favorite]

Ugh, I realize I didnt answer your percentage question. With nuclear winter, the idea seems to be that there is a good chance humanity would be near-whiped out, if not gone altogether. But even assuming that we will only have a "small" nuclear war, there seems to be a chance that a good 50% of the population would die in the years to come and that people in urban centres would be particularly vulnerable.

See also the year without a summer (a comparatively mild cooling event) and this article on the Toba bottleneck.
posted by miorita at 6:35 PM on December 30, 2016 [1 favorite]

Sorry about the multi-posting, but this comment on the blue is quite interesting. From the comment:

Government and utility industry officials regularly monitor the nation’s electrical grid because it is highly computerized and any disruptions can have disastrous implications for the function of medical and emergency services.
posted by miorita at 6:37 PM on December 30, 2016