6 ms·

I'm not sure "peak baby" is a good thing, but agree with you that the other three peaks are encouraging. Arguments by smart people like Sabine Hossenfelder hav

• Lord-Jobo 2y ago
  I think peak baby is less about good or bad and more about a turning point for growth demand.
• jl6 2y ago
  Conventional wisdom on population growth is that it’s a solved problem and that the population will inevitably stabilize or decline. I say let’s not count our chickens just yet. There are still countries and groups where the growth rate hasn’t stabilized at all, and even if these are small today, exponential growth means they soon won’t be. Population growth will continue until everyone agrees it shouldn’t.
  • missedthecue 2y ago
    Due to the dynamics of demography, a population is either exponentially growing or exponentially shrinking. A stable population is an unrealistic goal.
    • svnt 2y ago
      You’ll have to provide a lot more context for this to be believable. Maybe it is an unrealistic goal for animals who aren’t interested in having a stable global population.
      • nostrademons 2y ago
        It follows naturally from differential equations that describe population: dPop / dt = fertility rate * pop (birth rate) - deaths Note the "current population" factor in that. As long as the number of births depends on the current population (i.e. anyone has a chance to give birth), this equation will result in an exponential curve. If the fertility rate is greater than replacement rate (that "deaths" term that I've handwaved away), the population will exponentially grow. If it's less than the replacement rate, the population will exponentially decay. But it is necessarily exponential, because it's a constant rate multiplied by the current population, and if you remember your calculus, an exponential is defined by a constant growth rate. There's a whole subfield of population dynamics, and I remember lots and lots of predator/prey models, resource constraint models, etc. from my applied calculus class. Some of those do have non-exponential growth curves, eg. a basic 2-species predator/prey model gives rise to sinusoidal population curves as the increase in prey leads to an increase in predators, which results in more of the prey being killed and eaten, which results in a decrease of food, which results in the predators dying off. But what they all have in common is death rates that are proportional to some function of the current population. In other words, you have to kill off proportionally more of the current population based on how many people they are, something which would be ethically unacceptable to most humans. If you just have natural deaths (i.e. a death rate proportional to Pop(t - life expectancy)), you always get either exponential growth or exponential decay, because that's the way the math works. I suppose there was one other population curve that gives a sigmoid function (i.e. a logistic curve that asymptotically approaches a limit but never reaches it). This is what you get when there is a natural resource limit to giving birth, i.e. when instead of births being fertility rate * total population, it's fertility rate * (exponentially decreasing fraction of the population). Many people find this scenario ethically challenging as well: in plain English, it means that only the elite can afford to have kids, or alternatively - cap the number of houses so that only the top X families can have a house and raise a child, and then create social stigma around having kids when you cannot afford those increasingly scarce markers of stability. It is disturbingly close to reality, though.
        • missedthecue 2y ago
          Fantastic explanation, better than I could have put into words. Thanks for filling in.
        • adrianN 2y ago
          Luckily there are many fertility rates that are indistinguishable from "stable population" over a span of a couple generations, say 100 years or so. That means there is plenty of time for policy shifts to incentivize or disincentivize having children.
          • missedthecue 2y ago
            At current fertility rates, Europe's population is going to halve in 3 generations, and who remains is going to be quite old on average. I don't know your age, but if you're young enough this will happen within your lifetime. It's not a distant and abstract problem. I am not accounting for immigration of course, but from the wider point of view, immigration is musical chairs. Sri Lanka is well below replacement and still falling fast. Who is going to immigrate there? Ditto for most other countries.
        • jl6 2y ago
          Right, but what most people mean by stable population is a population that doesn’t fluctuate outside of a range. A population that grows and shrinks but has some kind of negative feedback that causes it to oscillate around a value, is stable enough, even if the local behavior of the curve is exponential.
          • nostrademons 2y ago
            That sort of sinusoidally oscillating population is certainly possible, but be careful what you wish for. The negative feedback, as far as population is concerned, is "death". Before the exponentially-growing post-Industrial population, we'd have periodic wars/famines/plagues that result from the population of an area outgrowing its local carrying capacity. That's not generally considered a good thing.
  • colechristensen 2y ago
    It’s nothing about agreement. Everywhere has declining birth rates once they hit a modern standard of living for at least a couple of generations. Not because people think fewer children are a good idea, but because having many children in modern world is unpleasant and very few want more than two. I think it mostly has to do with increasing desires for a high standard of living when it becomes possible and the pressure of high density cities making lots of kids an unattractive prospect.
    • jl6 2y ago
      While we do observe a trend towards lower fertility rates as wealth/health/modernity increases, this isn’t universal. For example, there is a big gap between the fertility rates of religious and non-religious people in the arguably modern USA. It only takes one such group to carry on the tradition of exponential growth.
• faeriechangling 2y ago
  A shrinking population is fine, this planet has its limits. A rapidly shrinking population is not ideal.
  • jandrese 2y ago
    There is a lot of panic over shrinking population where people project it out 1000 years and find there are only like 5 people left in the world. Steady state population should be the long term goal, at least until we start moving into orbital colonies or something. But unfortunately that's an anathema to growth oriented economies which makes it the bad guy in economics and politics.
    • faeriechangling 2y ago
      I mean Japan hasn't been doing great but it's been doing fine, so I don't think the end of growth has to mean anything but a period of stagnation. The economy will be fine.
      • missedthecue 2y ago
        In your lifetime, Korea will have more than two 60+ year olds for every working person. They are screwed.
        • hi-v-rocknroll 2y ago
          Korea also has a cultural practice of extreme ageism. So much so that the elderly are frequently impoverished to the point of food insecurity and committing suicide by jumping from bridges.
    • missedthecue 2y ago
      At fertility rates of 1.6, it takes just 25 generations for the global population to go from 8 billion to 900k. Just 10 generations for the global population to drop below 1 billion. Pretty scary stuff.