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I strongly suspect that our species is already on its way to inevitable extinction, and much more quickly than a few hundred years. Barring some science fictio

I strongly suspect that our species is already on its way to inevitable extinction, and much more quickly than a few hundred years. Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Children who grow up in a low-fertility environment learn behaviors and personality traits that encourage and enhance the already-low fertility, and any who are atypical and have above-replacement fertility themselves are never enough to get the global average back to (or above) replacement. Not only have we trained the kids to have few kids themselves, we've trained them to train those few kids of their own the same (but with extra!). You can disagree, almost everyone does. But the implications of disagreement are bizarre, you must imagine some future where all 5th generation-only children wake up and say "I want 2.1 children" or 10 percent of those 5th generation children wake up and say "I want 20 children".

grondilu 11y ago
Long ago I read "essai de prospective demographique"[1] written by French demographers. They were raising the concerns you mention and were trying to warn the public of a coming "demographic winter". So your point of view is not rare. That being said, even if a demographic winter would probably have very adverse consequences, as it is not clear how well the industrialized society would fare if the population was drastically reduced, I have hard time picturing how that could lead to the complete extinction of mankind. There will always be pockets of population with high fertility, at the very least among highly religious communities. Even if as you suggest reproductive behavior is transmitted, that works both ways, and simple natural selection will always, in the end, favor the reproductive behavior that leads to increasing numbers. Demographic winter is a serious concern, but I can't imagine it leading to a complete extinction. 1. https://books.google.fr/books/about/Essai_de_prospective_d%C3%A9mographique.html?id=lz9mPQAACAAJ&hl=fr https://books.google.fr/books/about/Essai_de_prospective_d%C...
- NoMoreNicksLeft 11y ago
  > There will always be pockets of population with high fertility, What makes you say that? Is there some underlying principle I've failed to consider? > I have hard time picturing how that could lead to the complete extinction of mankind. It's simple math. Below-replacement fertility leads to extinction. More people die than are born, and since the original number is finite, the end number must be zero. If you think that will not happen, what you're imagining is that the fertility rate will either rise at some point in the future, or at least plateau at whatever number leads to a stable population. Why would they rise? If you grow up in a world where everyone around you has few children, then you grow up thinking/feeling that few children is the way things should be. You have few yourself. You might even have fewer than your parents' generation... but you'll rarely if ever have more. On average, you'll never have more. Even in the fertility hot spots, this is true. They're above replacement fertility still, but each generation has a lower number. It's not exactly some sort of hidden trend, it's pretty basic. > at the very least among highly religious communities. It looks like the children of these communities break away from their religious upbringing at a higher rate than their pious siblings can replace with nephews and nieces. Especially in those religious communities that are unable to achieve a healthy economy... the FLDS communes that dispose of their sons, the ultraorthodox jews in their own self-imposed ghettos where there is little employment to be had. > Even if as you suggest reproductive behavior is transmitted, That's a little silly of me, actually. It must be the one behavior pattern that isn't transmissible. > and simple natural selection will always, in the end, favor the reproductive behavior The natural universe has no favorites. It does not preclude this sort of extinction. Those few who buck this trend will be starved for adequate mates at some point, and will raise their own children in a culture that ostracizes fertility...
  - grondilu 11y ago
    > What makes you say that? Is there some underlying principle I've failed to consider? Low fertility rates is a statistical rule. It's not absolute. There will always be people with high fertility, at the very least because they will be at the edge of the bell curve. Also again, look at religious communities, like the Amish. Those people do exist. Among seven billion human beings, you certainly can find a few millions that are very much willing to make babies. It only takes a small minority to ensure that the numbers will not go to zero. > The natural universe has no favorites. It does not preclude this sort of extinction. The lineage of people who don't have children will simply disappear, leaving room for the lineage of people who do. It's as simple as that. > Why would they rise? The fertility rate will rise because people with low fertility rate will die with no children. What will remain will be the children of people with high fertility rate, and presumably those children will have a similar reproductive behavior than their parents. Low fertility reproductive behavior will be "naturally" filtered out. > Those few who buck this trend will be starved for adequate mates at some point, and will raise their own children in a culture that ostracizes fertility... Fertility declines, but it's quite a stretch to talk about ostracization of fertility. And ostracization is not prohibition.
mikeash 11y ago
Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one. Use Japan's fertility rate and you can roughly double those numbers. I also don't see why disagreement has bizarre implications. World fertility rate is still somewhat above replacement, so all you really need is for the populations currently having lots of babies to keep on doing so. And even if the trend continues way downwards, reversal doesn't require weird scenarios where all children suddenly decide to have twice as many children as their parents. If fertility rates go from 1.5 to 2.5 over the course of ten generations, that would do it too. Nobody really understands why fertility rates drop with wealth, so it's not weird to think that further changes could cause them to increase again, especially in a world with a much lower population than today.
- NoMoreNicksLeft 11y ago
  > World fertility rate is still somewhat above replacement, World fertility is only above replacement because of a few hot spots that have high fertility. As those cultures are converted to something more western-looking, fertility plummets. You're postulating that, somehow, this will reverse and those places will convert the west to something not-so-western-looking, or that they'll fail to convert. Both of these seem very unlikely. Do you see any trends or evidence that either of those will come to pass? > Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one. It's a compounding effect. When there are only one thousand people, you still expect those who grew up in such an environment will still somehow manage a fertility rate of 1.0? What will allow you to hit 1.0 and plateau at that for 33 generations? > Nobody really understands why fertility rates drop with wealth, That's easy to understand. As individuals can be mentally ill, so can large groups of people be so collectively. And collectively, the world is neurotic. > so it's not weird to think that further changes could Yes, miracles will happen.
  - 11y ago
dragonwriter 11y ago
> Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Its dropped because of shifting economic incentives. Its pretty simple to shift those incentives to shift it back the other way to some degree (and almost certain to happen if, for an extended period of time, the developed world sees negative overall growth counting both natural growth and immigration.) > You can disagree, almost everyone does. But the implications of disagreement are bizarre, you must imagine some future where all 5th generation-only children wake up and say "I want 2.1 children" or 10 percent of those 5th generation children wake up and say "I want 20 children". No, I just imagine a future where policymakers -- having known for generations the policy factors which promote low birth rate -- look at the situation in their countries, recognize that negative natural growth is no longer being offset by immigration, tweak the policies so that reproduction is more incentivized, resulting in the overall growth rate rising out of negative territory. Its not people magically waking up with different preferences, its people reacting to different situations with different policies and changing the payoff matrices people face in society with the same preferences.

grondilu 11y ago

Long ago I read "essai de prospective demographique"[1] written by French demographers. They were raising the concerns you mention and were trying to warn the public of a coming "demographic winter". So your point of view is not rare. That being said, even if a demographic winter would probably have very adverse consequences, as it is not clear how well the industrialized society would fare if the population was drastically reduced, I have hard time picturing how that could lead to the complete extinction of mankind. There will always be pockets of population with high fertility, at the very least among highly religious communities. Even if as you suggest reproductive behavior is transmitted, that works both ways, and simple natural selection will always, in the end, favor the reproductive behavior that leads to increasing numbers. Demographic winter is a serious concern, but I can't imagine it leading to a complete extinction. 1. https://books.google.fr/books/about/Essai_de_prospective_d%C3%A9mographique.html?id=lz9mPQAACAAJ&hl=fr https://books.google.fr/books/about/Essai_de_prospective_d%C...

NoMoreNicksLeft 11y ago
> There will always be pockets of population with high fertility, What makes you say that? Is there some underlying principle I've failed to consider? > I have hard time picturing how that could lead to the complete extinction of mankind. It's simple math. Below-replacement fertility leads to extinction. More people die than are born, and since the original number is finite, the end number must be zero. If you think that will not happen, what you're imagining is that the fertility rate will either rise at some point in the future, or at least plateau at whatever number leads to a stable population. Why would they rise? If you grow up in a world where everyone around you has few children, then you grow up thinking/feeling that few children is the way things should be. You have few yourself. You might even have fewer than your parents' generation... but you'll rarely if ever have more. On average, you'll never have more. Even in the fertility hot spots, this is true. They're above replacement fertility still, but each generation has a lower number. It's not exactly some sort of hidden trend, it's pretty basic. > at the very least among highly religious communities. It looks like the children of these communities break away from their religious upbringing at a higher rate than their pious siblings can replace with nephews and nieces. Especially in those religious communities that are unable to achieve a healthy economy... the FLDS communes that dispose of their sons, the ultraorthodox jews in their own self-imposed ghettos where there is little employment to be had. > Even if as you suggest reproductive behavior is transmitted, That's a little silly of me, actually. It must be the one behavior pattern that isn't transmissible. > and simple natural selection will always, in the end, favor the reproductive behavior The natural universe has no favorites. It does not preclude this sort of extinction. Those few who buck this trend will be starved for adequate mates at some point, and will raise their own children in a culture that ostracizes fertility...
- grondilu 11y ago
  > What makes you say that? Is there some underlying principle I've failed to consider? Low fertility rates is a statistical rule. It's not absolute. There will always be people with high fertility, at the very least because they will be at the edge of the bell curve. Also again, look at religious communities, like the Amish. Those people do exist. Among seven billion human beings, you certainly can find a few millions that are very much willing to make babies. It only takes a small minority to ensure that the numbers will not go to zero. > The natural universe has no favorites. It does not preclude this sort of extinction. The lineage of people who don't have children will simply disappear, leaving room for the lineage of people who do. It's as simple as that. > Why would they rise? The fertility rate will rise because people with low fertility rate will die with no children. What will remain will be the children of people with high fertility rate, and presumably those children will have a similar reproductive behavior than their parents. Low fertility reproductive behavior will be "naturally" filtered out. > Those few who buck this trend will be starved for adequate mates at some point, and will raise their own children in a culture that ostracizes fertility... Fertility declines, but it's quite a stretch to talk about ostracization of fertility. And ostracization is not prohibition.

mikeash 11y ago

Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one. Use Japan's fertility rate and you can roughly double those numbers. I also don't see why disagreement has bizarre implications. World fertility rate is still somewhat above replacement, so all you really need is for the populations currently having lots of babies to keep on doing so. And even if the trend continues way downwards, reversal doesn't require weird scenarios where all children suddenly decide to have twice as many children as their parents. If fertility rates go from 1.5 to 2.5 over the course of ten generations, that would do it too. Nobody really understands why fertility rates drop with wealth, so it's not weird to think that further changes could cause them to increase again, especially in a world with a much lower population than today.

NoMoreNicksLeft 11y ago
> World fertility rate is still somewhat above replacement, World fertility is only above replacement because of a few hot spots that have high fertility. As those cultures are converted to something more western-looking, fertility plummets. You're postulating that, somehow, this will reverse and those places will convert the west to something not-so-western-looking, or that they'll fail to convert. Both of these seem very unlikely. Do you see any trends or evidence that either of those will come to pass? > Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one. It's a compounding effect. When there are only one thousand people, you still expect those who grew up in such an environment will still somehow manage a fertility rate of 1.0? What will allow you to hit 1.0 and plateau at that for 33 generations? > Nobody really understands why fertility rates drop with wealth, That's easy to understand. As individuals can be mentally ill, so can large groups of people be so collectively. And collectively, the world is neurotic. > so it's not weird to think that further changes could Yes, miracles will happen.
- 11y ago

dragonwriter 11y ago

> Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Its dropped because of shifting economic incentives. Its pretty simple to shift those incentives to shift it back the other way to some degree (and almost certain to happen if, for an extended period of time, the developed world sees negative overall growth counting both natural growth and immigration.) > You can disagree, almost everyone does. But the implications of disagreement are bizarre, you must imagine some future where all 5th generation-only children wake up and say "I want 2.1 children" or 10 percent of those 5th generation children wake up and say "I want 20 children". No, I just imagine a future where policymakers -- having known for generations the policy factors which promote low birth rate -- look at the situation in their countries, recognize that negative natural growth is no longer being offset by immigration, tweak the policies so that reproduction is more incentivized, resulting in the overall growth rate rising out of negative territory. Its not people magically waking up with different preferences, its people reacting to different situations with different policies and changing the payoff matrices people face in society with the same preferences.