If you only have 80,000 people left, they’re probably randomly all over the world and they’re probably not going to end up in one place that quickly.
So then things like earthquakes, they just won’t affect the different groups — it’s hard to have a thing that affects all of them. Climate effects plausibly get closer to affecting all of them, but even climate effects just don’t affect the whole world equally, basically, ever.
Luisa Rodriguez
If modern human civilisation collapsed — as a result of nuclear war, severe climate change, or a much worse pandemic than COVID-19 — billions of people might die.
That’s terrible enough to contemplate. But what’s the probability that rather than recover, the survivors would falter and humanity would actually disappear for good?
It’s an obvious enough question, but very few people have spent serious time looking into it — possibly because it cuts across history, economics, and biology, among many other fields. There’s no Disaster Apocalypse Studies department at any university, and governments have little incentive to plan for a future in which almost everyone is dead and their country probably no longer even exists.
The person who may have spent the most time looking at this specific question is Luisa Rodriguez — who has conducted research at Rethink Priorities, Oxford University’s Future of Humanity Institute, the Forethought Foundation, and now here, at 80,000 Hours.
She wrote a series of articles earnestly trying to foresee how likely humanity would be to recover and build back after a full-on civilisational collapse.
In addition to being a fascinating topic in itself, if you buy philosopher Derek Parfit’s argument that the loss of all future generations entailed by human extinction would be a much greater moral tragedy than the deaths of even as many as 99% of humans alive, it’s also a question of great practical importance.
Luisa considered two distinct paths by which a global catastrophe and collapse could lead to extinction.
The first is direct extinction, where, say, 99.99% of people die, and then everyone else dies relatively quickly after that.
There are a couple of main stories people put forward for how a catastrophe like this would kill every single human on Earth — but as we’ll explain below, Luisa doesn’t buy them.
Story One:
Nuclear war has led to nuclear winter. There’s a 10-year period during which a lot of the world is really inhospitable to agriculture, and it takes a lot of ingenuity to find or grow any alternative foods. The survivors just aren’t able to figure out how to feed themselves in the time period, so everyone dies of starvation or cold.
Why Luisa doesn’t buy it:
Catastrophes will almost inevitably be non-uniform in their effects. If 80,000 people survive, they’re not all going to be in the same city — it would look more like groups of 5,000 in a bunch of different places.
People in some places will starve, but those in other places, such as New Zealand, will be able to fish, eat seaweed, grow potatoes, and find other sources of calories. Likewise, people in some places might face local disease outbreaks or be hit by natural disasters — but people will be scattered far apart enough that other groups won’t be affected by regional disasters.
It’d be an incredibly unlucky coincidence if the survivors of a nuclear war — likely spread out all over the world — happened to all be affected by natural disasters or were all prohibitively far away from areas suitable for agriculture (which aren’t the same areas you’d expect to be attacked in a nuclear war).
Story Two:
The catastrophe leads to hoarding and violence, and in addition to people being directly killed by the conflict, it distracts everyone so much from the key challenge of reestablishing agriculture that they simply fail. By the time they come to their senses, it’s too late — they’ve used up too much of the resources they’d need to get agriculture going again.
Why Luisa doesn’t buy it:
We‘ve had lots of resource scarcity throughout history, and while we’ve seen examples of conflict petering out because basic needs aren’t being met, we’ve never seen the reverse.
And again, even if this happens in some places — even if some groups fought each other until they literally ended up starving to death — it would be completely bizarre for it to happen to every group in the world. You just need one group of around 300 people to survive for them to be able to rebuild the species.
———
The other pathway Luisa studied is indirect extinction: where humanity stabilises things and persists for hundreds or thousands of years, but for some reason gets stuck and never recovers to the level of technology we have today — leaving us vulnerable to something like an asteroid or a supervolcano.
But Luisa isn’t too worried about that scenario either.
Luisa’s best guess for how long it might take to recover — given that we’d already have the knowledge that agriculture and even more advanced technologies are possible, as well as artifacts to reverse engineer — is a couple thousand years at the longest.
And because it seems like the natural rate of extinction for humanity as a hunter-gatherer species has to be pretty low — otherwise we probably wouldn’t have been around in one form or another for 100,000 to a million years — it just seems like humanity would probably have plenty of time to rebuild.
When Luisa started this project, she thought, “I don’t know how to do any of the stuff we’d need to survive — I couldn’t grow a potato if my life depended on it, let alone reestablish more complex technologies. We’d be doomed.” But some wild examples of human ingenuity from the past made her realise that maybe other people are a bit more practical than she is, such as:
- During the Serbian bombing of Bosnia, people generated electricity by pulling engines out of cars and putting them into rivers in a way that generated hydropower.
- After the fall of the Soviet Union, Cuba realised they were going to lose their access to trucks — so they spent years breeding oxen to manually plough fields, which allowed them to keep generating food.
- In World War II, people in POW camps built radios out of things like gum wrappers and pennies — allowing them to listen to music and the news.
Even just the fact that two billion people alive today practise subsistence farming — and therefore already know much more than she does about producing food — made Luisa realise that while she might be especially poorly equipped to survive a catastrophe, that doesn’t mean everyone else would be.
And having collected all this knowledge, Luisa admits that she too will now be a valuable member of a post-apocalyptic world!
In this wide-ranging and free-flowing conversation, Luisa and Rob also cover:
- What the world might actually look like after one of these catastrophes
- The most valuable knowledge for survivors
- What we can learn from fallen ancient civilisations and smaller-scale disasters in modern times
- The risk of culture shifting against science and tech
- How fast populations could rebound
- Implications for what we ought to do right now
- ‘Boom and bust’ climate change scenarios
- And much more.
Get this episode by subscribing to our podcast on the world’s most pressing problems and how to solve them: type 80,000 Hours into your podcasting app. Or read the transcript below.
Producer: Keiran Harris
Audio mastering: Ben Cordell
Transcriptions: Katy Moore
