alt Hacker NewsBelow replacement would be terrifying if there were one thousand humans, it would be worrying if there were a million, and at least worthy of consideration if there were a hundred million, but there are almost ten billion simultaneous humans, we're fine.
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>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.
On a humanity-level: yes.
On an individual state-level: no.