>Below replacement would be terrifying if there were one thousand humans,

The funny part is that it should terrify you whether there are 10 humans or 10 billion. At the current rates, it's over in about 12-13 generations regardless of the number you start with. That's how it works... no matter how big the starting number, it's how many generations you have left.

Think of it this way? You know the dumb story they taught us in school, about the guy whose payment from the king for doing something clever was to have one grain of rice on the first chess square, and 2 on the second, 4 on the third, and so on... and how it bankrupted the king long before the 64th square? That's the same math with fertility rate of 1.0! (The Chinese have a fertility rate of 1.0, famously.) Each generation will be half the size of the previous. But how long before that is effectively zero? Will it be 1 million years, 250,000 years? No, about 300ish. 300 years. But long before you reach that point, your civilization has fallen apart. Those last 4 or 5 generations live life without electricity, anything but muscle power, or metallurgy.

And China's fertility rate isn't even the lowest! South Korea's rate just dropped to around 0.5! That's where each generation is one quarter the size of the previous.

The best part of all is that these rates haven't even bottomed out. We will almost certainly see rates right around 0 long before the century ends.

>but there are almost ten billion simultaneous humans, we're fine.

At least math illiteracy ought to console you guys towards the end.

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yoyohello13 4 hours ago | parent | next [-]

This whole comment rests on a very big assumption that these rates will never recover. Just because you can fit a trend line doesn’t mean the projections will pan out. It could just as easily be the case that once population starts meaningfully decreasing, the opportunity cost of children will also decrease and fertility rates will recover. This happens all the time in nature.

Our population absolutely exploded over the last 100 years. This can easily just be a reversion to the mean. There really is no reason to be worrying about human extinction right now. In fact, the ‘extinction’ rhetoric is harmful and dangerous since so many ‘solutions’ to fertility rates are less education and less freedom. I have no trouble believing a handmaids tail like faction emerging because they believe they are saving the species.

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NoMoreNicksLeft 3 hours ago | parent | next [-]

>This whole comment rests on a very big assumption that these rates will never recover. J

The opposite, actually. Your assumption is that the rates bounce up and down, mostly because you don't want to believe there's a problem.

The rates are transmissible, older generations to the younger. No one growing up in a world where people have few or just one child will say to themselves "hey, you know what, I want 10 kids when I'm an adult!"... but that's what would have to happen. You and everyone else on HN whines "the reason people aren't having kids is the economy is awful and we can't afford them"... but in a world with a shrinking, aging population the economy just gets worse.

You're the one making the very stupid assumption, and you can't even say why. I can, it's because you haven't thought about it. Perhaps it's uncomfortable to think that you're driving your species to extinction.

>Our population absolutely exploded over the last 100 years.

More nonsense. Our population isn't exploding, it's just big. And it will shrink rapidly. I already laid out the math... how long before 8 billion becomes 1000 when you're splitting it in half every generation (a generation is commonly held to be 20-25 years)? Can you do that math puzzle for us? There are only about 5 generations living on Earth at any given time. Just do the math already. None of this is pretty.

>There really is no reason to be worrying about human extinction right now.

Yes, there is. People are only generally capable of reproduction from the ages of 16 to 36... just 20 years. Every moment you waste "not worrying about it now" is the problem compounding with interest. You've already waited too long to worry about it.

>In fact, the ‘extinction’ rhetoric is harmful and dangerous since so many ‘solutions’ to fertility rates are less education and less freedom.

Well at least when our species dies out, the last few people will have masters degrees. That's the important part, right?

>I have no trouble believing a handmaids tail like faction emerging

It'd be because you and those like you forced the issue. Go ahead, stick your head in the sand some more. We all know that willful obliviousness to reality can change the rules of the universe themselves, right? Wish it all away!

	▲	tsimionescu 2 hours ago \| parent \| next [-]
		> The rates are transmissible, older generations to the younger. No one growing up in a world where people have few or just one child will say to themselves "hey, you know what, I want 10 kids when I'm an adult!"... but that's what would have to happen. And yet this exact thing happened, in reverse, everywhere in the world as certain social conditions were met. So it's not just not impossible, it's by far the likeliest scenario. > Our population isn't exploding, it's just big. And it will shrink rapidly. The whole population of the world slowly rose from some 10-50 million before 1 CE to some 100 million by 1000 CE, to maybe some 2-300 million by 1700 CE. And then it suddenly reached 1B in 1800, 2B in 1920, 4B in 1974, 8B in 2022. This is a massive population explosion, with the doubling rate increasing rapidly, especially before the 2000s. > People are only generally capable of reproduction from the ages of 16 to 36... just 20 years. This is wildly wrong. Children of 16 years should NEVER reproduce, it's an awful thing that this happened for so long of human history, a shameful reality that will hopefully never happen again. And as health has increased, women have become able to reproduce (with some medical aid) well into their 40s (note that the record is currently 74), while men can and often do reproduce well into their 60s+. Now, is it better if people who want to have children have them when they're younger, probably in their late 20s? Absolutely - mostly to keep generational gaps manageable, to benefit from grandparents' help, etc. But it's not in any way a strict biological necessity, and as fertility science advances, we have every reason to believe this will continue to improve. > Well at least when our species dies out, the last few people will have masters degrees. That's the important part, right? This is absurd hyperbole for the exact reasons above.
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AnimalMuppet 2 hours ago | parent | prev [-]

When will the trend recover? When civilization falls to the point that nobody can make birth control pills, if not before.

	▲	Jare 25 minutes ago \| parent [-]
		It recovers when having 1.1 kids per person on average does not mean making substantial sacrifices in quality of life over your entire life. Since many people will still not have kids, that sounds like 3 kids per couple being affordable in a comfortable, enjoyable, not stressful manner. Right now you can guess that for many couples, 2 kids becomes close to unaffordable, and 3 becomes nearly unmanageable. Individually, you will see couples choose to do it and even to do it in ways that others both envy and chastise; but overall, it's not happening. It requires many things to change not just in economy, but in society as a whole. It's not going to happen in a society devoted to growth, that's for sure.

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InsideOutSanta 35 minutes ago | parent | prev | next [-]

No, this should absolutely not terrify anyone, at all. The only reason it is a concern is that our economic system is built on infinite growth, which is going to fail one way or the other eventually. It's better it fail by people voluntarily having fewer kids than any of the other possible fail states.

The solution is to fix the economic system, not to worry that teenagers aren't getting accidentally pregnant so much anymore.

Productivity is increasing all the time, and we're very likely on the verge of another huge productivity increase with LLMs and robotics. The idea that we need to constantly increase the number of humans to maintain our current economic system is absolutely asinine.

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CalRobert 3 hours ago | parent | prev [-]

The way emissions are going we* won't make it another 12-13 generations either.

* Some humans will likely survive, but modern civilisation won't.