"Soonish" at the time scales of current demographic trends is still hundreds, if not thousands, of years for even the most rapidly aging country.

And cease to exist is a bit dramatic, certainly populations will decline given the current replacement rates in many westernized countries, but they aren't going to disappear. They will decline to some lower steady state, but nowhere near zero.

South Korea: population of 51.7 million, annual population growth rate -0.2%. Vanishing from the world map isn't quite imminent.

They could simply let in 100,000 immigrants to fix the growth rate. I know it's not as simple as that in a society like Korea's, but 100k is perfectly manageable for such a large country. Take primarily young people with some useful level of education. They'll work, learn the language, marry, and start new families that become primarily Korean.

Think like a state. No surplus population means that soldiers aren't disposable. No disposable soldiers might lead to vanishing from the world map.

According to Google, Russia's rate is -0.4%, this might be the last war they can afford.

China didn't end their one-child policy out of a great love for children.

Where is South Korea supposed to find 100,000 South Koreans to immigrate?

Like other immigrants around the world, they gradually become Koreans when they work, learn the language, marry, have children, and spend the rest of their lives there.

(Of course South Korea's case is very particular because they actually have an enormous reserve of eager potential immigrants who already speak the language, living just across their land border, an hour away from Seoul. The problem is that the other side of the border won't let anyone go.)

Is that supposed to be a joke? You have a lot to learn about genetics if you think that's why South Korea is full of South Koreans. I'm a White guy - it doesn't matter how hard I work or how good my Korean is, or even my marital status - I can never be a South Korean.

That's a problem of attitude, not genetics. A person born in Korea can become American, British, Swedish, Singaporean, Brazilian, etc. There's no fundamental reason why it wouldn't work the other way if Koreans wanted their society to be open to newcomers. With shrinking population they may want to have that national conversation eventually.

Anyway, when you bring in young single people, the primary cultural diffusion is through their eventual children. They will be Korean in a way that the immigrant parent might never personally feel.

I'm quite sure that South Koreans aren't so much concerned about the declining number of people occupying the area within the arbitrary geographical border known as "South Korea" so much as they are concerned about the declining number of ethnic South Koreans.

To put it crudely, if South Korea was invaded, the indigenous people genocided and the area colonised by a billion foreigners, I don't think South Koreans would regard that as a boon for their demographics.

Doing this more slowly via immigration is not fundamentally different.

It's entirely different if the newcomers are primarily young and single and start families with non-immigrant Koreans. Seeing that as problematic is a slippery slope into Nazi-style racial heritage mathematics where you'd be obsessing over who's only 3/8 Korean, etc.

We'll have to disagree there. I'd much rather be called names than be complicit in the demographic replacement and genocide of my people. I'd even argue that crossbreeding would be more catastrophic for the South Korean ethnicity than population decline. The latter is recoverable as the stock of the nation remains intact, while the former permanently alters the genotype of the population - even if the numbers recover, this is not fundamentally the same people as those who existed before.

dismissing the concept of ethnicity may be appealing in the Western bubble but you will find few takers in the rest of the world.

to reduce the NK situation to "they won't let anyone go" is also disingenuous. even if you ignore that the US refuses to allow any more meaningful peace so it can justify a continued military presence halfway across the globe, the US and South Korea are clearly more powerful and wealthy. clearly they are in a better position than NK to make concessions and pave the way for integration.

I suspect one reason NK developed nukes is precisely because their leadership don't want to be "integrated".

The claim is that they don't have to be Korean. This is generally true for most immigrants.

But if they did, and for whatever reason none of the emigrants wanted to go back to the old country, there's a whole extra Korea just on the northern border, and they used to be the same country…

North Korea

This -0.2% figure you're citing is hiding rapidly aging population. TFR is 0.8. They'd have to let in about half a million immigrants, every year.

Unless the immigrants adopt Korean culture, then even then, Korea won't exist.

So we should rather be saying that America and Canada and Sweden won't exist?

> Canada and Sweden

Both of these countries now have ethnical enclaves, thanks to multiculturalism. So I'd say yes.

Population decline happens much faster than you intuitively expect. Each generation is slightly smaller than the one before it.

Current fertility rate in Korea is 0.78/woman

Gen1 = 100 Gen2 = 78 Gen3 = 60 Gen3 = 46

You need 2 people for a couple. So it would be

Gen 1 - 100, Gen 2 - 39, Gen 3 - 16, Gen 4 - 6

Speaking off the cuff, I'm not sure that nations can be strictly, or even mostly, defined by their ethnicity. I would need to do some numbers to say anything more formally, but I constantly come back to Israel, Rome, Turkey, even China, where the "nation" had such imminent prestige that myriad ethnicities took on its "nationhood" upon entering/invading/outbreeding even while having zero common parentage with the founders. Did the meta-nations lose something in the process? Sure. Did they endure? I'd say yes. Your nation doesn't necessarily stop because its people are suddenly able to sprout fantastic moustachios. But boy, is that a sore topic. It might actually be the sorest.

Great piece, btw.

Japan is the example that immediately comes to mind for me of an ethnically-homogenous nation. My understanding is that someone who isn't ethnically Japanese can never truly "fully assimilate".

Yeah. As an industrialized country, you either subsidize childbirth, optimize immigration/naturalization/colonializations, or die. There's no third path that I can think of . . aside from deindustrialization. I guess Japan's working on artificial wombs and lots of robots? That might do the trick, I guess, but man . . what a brutal experiment that would be.

China and Rome for sure. But Turkey is a terrible example of your point. Byzantium (or the Roman empire as they called themselves) was absolutely conquered and replaced by foreigners.

Historically, the Turkish nation was ridiculously multi-ethnic though, wasn't it? You have Altai, Chuvash, Kyrgyz, actual Turcomen, who knows how many others. "I'm proud of my Turkish heritage and have been since I obtained it last week".

And yeah, Rome died hard in the East. No denying that. But it's worth noting they had, century after century, so many opportunities to ally and rebirth with other peoples - Syrians, Macedonians, Bulgars, Russians, French - only to stab them right in the kidneys at the absolute worst time. Byzantium was like if you took Black Adder and made him into an entire country. Or Cersei Lannister, in the bad years.

Have you considered that perhaps there are way too many people due to the industralization explosion and some negative population growth might be a good thing.

First off, this is just your anti-human opinion. "overpopulation" isn't anything approaching a fact.

Beyond that though, have you considered the second order effects of population reduction? What happens when the non-productive share of the population becomes 80%? How many things we enjoy in our way of life that are predicated on increasing populations?

Is it really pro-human to want to live like factory-farmed cattle? Nobody ever seems to engage with the fact that the population shot up, what, 10+ times in the last 200 years.

I'll happily engage with the fact. It's great news! Humans are awesome, all my favorite entities are humans! Everything good about my life was provided by me (a human) or another human. Hope it 10x's again!