Comment by somenameforme | Hacker News Reader

Comment by somenameforme | Hacker News Reader

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When we speak of the decline of Japan, what makes it so undesirable? Is it that the geographic location around 36N 138E will no longer have as large a human presence? Or is it that the culture of that region will fade from society? Obviously we both agree that it'd be the culture. Where we disagree is you want to argue that it's not going to disappear, but instead just be changed. And that's reasonable, since cultures do constantly change. Tempura is a great example. People think it's Japanese, and in some ways it is, but it was borrowed, more or less wholesale, from Portuguese traders.

But I'm sure you'd agree that if a culture changes 'quickly enough', it's not really changing it but basically deleting it. For instance I'm sure if you squint hard enough today, maybe there's some Native American influence on American culture, but for the most part we just destroyed it. And I don't think it was the violence, so much as the raw numbers. Something similar happened to the Maori in New Zealand without anywhere near the scale of violence, just lots of immigration and lots of babies.

So how fast will fertility change things? A fertility rate of 1 means each generation decreases in size by about 50%, but that's compounding. The length of a generation is proportional to the window of human fertility, which is about 20 years. So in an average human lifetime we'll each get to see around 4 generations play out. With a 50% compounding decline that means a generational decline in size of 94% in a human lifetime.

So if you want to try to deal with fertility declines with immigration, you're basically going to be replacing the entire population in extremely rapid order. So I don't think we really need to debate what 'quickly enough' means because it's way slower than what fertility collapse is going to do. And this is all far more true in places like Japan where you, out of necessity, are speaking of bringing in immigrants who the locals can't comfortably communicate with and who come from radically different cultures. So basically, from my perspective, I think you're speaking of having your cake and eating it too.

> So if you want to try to deal with fertility declines with immigration, you're basically going to be replacing the entire population in extremely rapid order.

Are you basing this on history and data because America is country of immigrants and its culture has survived for hundreds of years now by absorbing the cultures of immigrants and assimilating them within 1 generation. I haven’t looked at the numbers as closely but I feel that Canada and Australia have largely done the same. The countries with major issues are the ones with little to no experience with assimilation like France, Germany, or the UK

Also Japan and South Korea have tried nearly everything sans immigration like media (shows promoting Natalism), monetary incentives and other benefits, and so on, but nothing even made a dent except for immigration. Why do you think there are so many foreign workers in Japan now? For show?

Fertility imo is an even harder problem to solve than immigration issues because it’s not just a socioeconomic issue. Pollution with endocrine disrupters like BPA and PFAS are the likely culprits but they’re too embedded in our supply chain and there’s even less incentive to fix them

Indeed I am! The data are very surprising at first. This [1] is the US foreign born population since the census started measuring that in 1850. The US foreign born population peaked in the late 19th century, at 14.7%. That's about when you started seeing a bunch of anti-immigrant sentiment rising with people thinking it was having a negative affect on culture, society, labor, etc.

That sentiment gradually led to various restrictions on immigration sending it to a valley of 4.7% in 1970. In 1965 a new immigration act was passed that loosed the requirements and immigration rates began skyrocketing to where they are today at around 14.8%, with rising anti-immigrant sentiment emerging for the same reasons, at almost exactly the same percent.

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I 100% agree that getting fertility rates back up will be much harder than it was to bring them down, but fortunately I don't think environmental or other issues are playing a significant role yet, at least not in terms of direct infertility. The vast majority of people that are not having enough children are (or were) still fertile.

But ultimately it's not even a choice. On top of the cultural issues, I think immigration is simply also unrealistic on a long-term scale. All you do is just kick the can, and not even especially far. And even in places like South America, they're also experiencing a fertility rate collapse. Humanity is simply going to have to change how we're doing things, in a rather dramatic way.

It's not existential because it is the most absurdly self-correcting problem imaginable, but I'd rather we all just start having more babies than ending up in a world dominated by the e.g. Amish and Haredim. Though it'd be pretty funny if we do finally meet an alien intelligence, it turns out they went through the same sort of crisis, and as a result these enlightened aliens everybody has attributed every positive characteristic to end up being Space Mormons. 'Ah Earthling, can I have a minute to talk to you about Gazurazu the Great?'

[1] - https://www.census.gov/library/stories/2026/07/foreign-born-...

"Space Mormons" So, regular, "orthodox" Mormons?

> The US foreign born population peaked in the late 19th century, at 14.7%.

This is flawed because you're not even bothering to count the 2nd generation or generations after. The effect of immigration doesn't go away after the 1st.

> with rising anti-immigrant sentiment emerging for the same reasons, at almost exactly the same percent.

Yes, you've repeated this from another one of your comments. You're still pretending that assimulation doesn't happen.

"Yes, in the 19th century there was a lot of racism and prejudice directed towards the Irish, German, and Italian immigrants. Not surprisingly, they did not destroy US society or culture. Instead, the US absorbed respective parts of their cultures and assimulated all of their populations over decades. now they are an integral part of America"

> fortunately I don't think environmental or other issues are playing a significant role yet, at least not in terms of direct infertility > It's not existential because it is the most absurdly self-correcting problem imaginable

Unfortunately, there is mounting evidence that the more industrialized a country becomes, the more its populuation becomes infertile. Related studies account for socioeconomic changes i.e. even without socioeconomic changes like the sexual revolution, fertility would still trend down. Air pollutants, endocrine-disrupting chemicals, and heavy metals are linked to reduced sperm motility in men and accelerated ovarian aging in women globally, even in places that are more traditional culturally. The only region untouched now is Central Africa.

> But ultimately it's not even a choice. On top of the cultural issues, I think immigration is simply also unrealistic on a long-term scale.

America has relied on it since its inception. It has only reversed course recently. It's been proven to work for hundreds of years now. Canada has also relied on it since the 1970s since their birthrate was no longer sustainable. They also only reversed course recently.

What we're fundamentally speaking about is the scale of things. I'm certainly not aiming for a level where immigrants have no impact - I think controlled immigration where immigrants assimilate, and also bring their own flavor to society, is a great thing and win-win thing for everybody. But there's a point where if you bring in too many people you start essentially wrecking the host culture and causing social instability, exactly as Western colonization did to the various indigenous cultures in place we colonized.

Based on US history, the number seems to be around 15% of the population being foreign born at any given time. This ballpark also seems to be playing out throughout Europe as well. Germany's at 20.9%, Sweden ~20%, UK 19%, and so on. The exceptions that exist like in the Mideast are quite different. For instance Saudi Arabia has around 40% of their population foreign born, but those are all just temporary workers who will never be granted citizenship, and live under a very two-tier system. The temporary residents do not have anywhere near the social impact people who might eventually become citizens, or live in the country forever, do.

Now getting back to fertility collapse. A shared fertility rate of 1 will trend towards you losing approximately 2.5% of your population per year, compounding. So after 80 years, a single human lifetime, you'd have lost 87% of your population. If we're speaking of maintaining population levels with immigration, you'd need to have 87% foreign born at that point in time. So what I'm getting at with the 15% is we can argue whether it's 10%, 15%, 25% or whatever else. But whatever the exact number of 'good' immigration may be, it's much less than 87%.

And furthermore, when you start looking at the actual numbers involved here, it is literally impossible. If we say e.g. 60% of the world, by population, is losing 80% of their population of that timeframe, then there literally are not enough people to replace them in the rest of the world. That'd be a population decline of 48% (of the global population) and only 40% of people in the rest of the world. And that's if you're willing to just accept literally anybody, regardless of whether they have any skills, education, or can even speak your language. It's just not realistic at all.

Yeah, my understanding in Japan, South Korea, and most countries with "fertility problems" is that they have almost zero correlation with any personal human's "fertility problems": they instead have to do with too many humans simply choosing not to reproduce (and for shockingly many of them, choosing to avoid romantic partnership altogether).

The core of that in turn is that capitalism treats human beings as replaceable and disposable cogs in the "earn me enough money for another yacht" machine and nobody wants to reproduce when treated that way.

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