if the total fertility rate drops and stays below global replacement rate, will humans disappear? - eviltoast

After watching this video I am left with this question.

The video ultimately claims that humans will not disappear, but doesn’t do a great job explaining why.

Correct me if I’m wrong, but for the (or a) population to be and remain stable, the total fertility rate needs to be equal to the global replacement rate (which recently was 2.3).

And since the total average fertility rate appears to be currently at this 2.3, any drop in the fertility rate in place A would have to be compensated with a rise in the fertility rate in place B (assuming that, at some point, we would like to stop population decline)?

I guess one way for a population to remain stable, while women are having fewer than 2.3 children, would be to have fewer men? If a population has 100 women and 10 men, each woman would only have to have on average (a bit more than) 1.1 child? (Which would of course also require a collective form of prenatal sex selection.)

I realize that would be bonkers and unethical. Just wondering out loud.

  • Mediocre_Bard@lemmy.world
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    4 months ago

    If a generation is 25 years, there 7.9 billion people on Earth, and the replacement rate is 1.0, then humans will disappear in about 800 years.

    If we enforced a 1.0 replacement rate for two generations, the global population would decrease by 75%, leaving 1.9 billion people in play. This is the global population in 1919. If we go three generations, we could get down to 985ish million prople.

    That would be amazing for our climate goals and would be considered ethical and humane by most.

    • lovely_reader@lemmy.world
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      4 months ago

      Would the shrinkage in the labor force make it impossible to provide end of life care and financial support as the larger generations age?

      • LordGimp@lemm.ee
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        4 months ago

        Unlimited reproductive rights is also unethical. Unlimited growth is not sustainable in a finite environment. As masters of our environment, it is our moral responsibility to ensure our existence does not destabilize everything else. We’ve done so poorly as a species that the world is about to undergo a cataclysmic shift.

        • yes_this_time@lemmy.world
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          4 months ago

          Agreed we are not in a good spot and unlimited population is not sustainable. However, sex education, access to birth control, and strong women’s rights is the answer in my opinion not ‘enforcing’ limits - which reads as an authoritarian dystopia to me. Economic growth is good as long as it’s decoupled from natural resource use/impact.