5 ms·

Birth rates dropped to below replacement rate in the 70s near universally among developed countries, far before many of them became increasingly more individual

Birth rates dropped to below replacement rate in the 70s near universally among developed countries, far before many of them became increasingly more individualistic. American culture and attitude seeping into most of those countries kicked into overdrive the 21st century, but birthrates were already low by then.

CPLX 4y ago
The hidden variable here is the newly available innovation of birth control pills.
- deleted 4y ago
  [deleted]
- klipt 4y ago
  It's just nature's way of filtering out people who like sex but don't want kids. Prior to birth control, having a genetic predisposition toward liking sex was enough. In the future, most people will also have a genetic or cultural disposition towards wanting kids.
  - CPLX 4y ago
    > It's just nature's way of filtering out people who like sex but don't want kids. More like: It's just nature's way of filtering out people who like sex but don't want [more] kids [right now]. That’s a lot of people, and thus, less kids.
    - taneq 4y ago
      Taking it to its logical conclusion, it’s nature’s way of filtering out people who either (a) have good short term but poor long term planning, or (b) have good impulse control. Uhoh.
  - trashtester 4y ago
    Exactly this. A couple of centuries from now, people will laugh about that time people thought that the population will collapse. Most likely, there is an enormous selection pressure right now for any genes that predispose people (and in particular women) to want to have (many) kids. If those genes are as common as I believe, they should be dominant within about 10 generations (counting from approximately 1970).
    - jkhdigital 4y ago
      And that selection pressure hasn't existed for the entire history of life? I don't think genetics have nearly as much to do with it because we are not living in a "state of nature" where genetics are the dominant factor in reproductive fitness. Even Richard Dawkins recognized this many decades ago when he coined the term "meme" to refer to the units of cultural lineage that clearly influence evolutionary fitness by altering the behavior of the people who hold them. edit: I mean, you're not wrong, but I'd posit that there is enormous selection pressure for memes that promote fertility.
      - trashtester 4y ago
        > And that selection pressure hasn't existed for the entire history of life? Not at all. For most of evolutionary time, organisms didn't even have any kind of cognitive capacity at all (being single celled organisms). Even after brains started to develop, mating behavior was primarily instinctual. And even up until this day in humans, the sexual drive may easily overpower any desire to prevent pregnancy if people (and women in particular) doesn't have access to birth control. Arguably, the sexual drive may have been so strong that there may have been a selection pressure favoring INHIBATION of reproductive behavior (K selection). https://en.wikipedia.org/wiki/R/K_selection_theory https://en.wikipedia.org/wiki/R/K_selection_theory Especially so in females, as under some conditions, having fewer offspring and investing more in each may provide a higher number of surviving offspring than giving birth to more, but with less investment in each. Without birth control, even K-selection strategies ended up with 5 or so offspring per woman, on average, with about 2-3 surviving children on average. With child survival rates near 100%, K-selection strategies are now strongly disfavored compared to r-selection strategies, even without birth control. (So r-selection has probably been selected for at some level for the past 150 years or so in the West). Birth control simply multiplies this effect. > because we are not living in a "state of nature" This, I'm sure, is a fallacy. The rate of genetic adaptation is directly linked to the strength of selection pressures, where "selection pressures" are not just survival rates, but rather the number of surviving offspring. To quote wikipedia: "Contrary to popular belief, not only are humans still evolving, their evolution since the dawn of agriculture is faster than ever before" https://en.wikipedia.org/wiki/Recent_human_evolution https://en.wikipedia.org/wiki/Recent_human_evolution > "meme" to refer to the units of cultural lineage that clearly influence evolutionary fitness by altering the behavior of the people who hold them. Memes (as coined by Dawkins, not the pop culture use) are their own replicators. They code for the replication of thoughts and ideas. Memes are not very tightly coupled to the physical fleshbags they inhabit. Like regular viruses, they often pass from host to host laterally, even though some forms are often transferred to children. But there is no reason to think that this has limited genetic evolution (meaning adaptation, not necessarily "improvement"). This is basically orthogonal to whatever the memes are doing. (Though there is an interaction term where genes and memes form part of the natural environment of each other as replicators). Genes may not be the dominant factor in reproductive fitness right now, but unlike for memes, the relative frequency of genes depend directly on reproductive fitness, meaning whatever variance DOES ALREADY exist in the genome for reproductive fitness are under a massive selection pressure right now. For many, if not most memes, reproductive the reproductive fitness of the hosts has little impact on the ability of the meme to replicate. For some memes (or meme-plexes) like religions, one _could_ argue that they attach themselves strongly enough to families that they are inherited in a way similar to genes. However, I would argue that memes can lose this power much more quickly than genes can. Just consider how quickly Christianity have been losing power over most Western linages lately. Meanwhile, genes will continue to build up momentum for as long as the selection pressure remains. Currently, that pressure is for women to WANT to have children. While cultural effects may come and go, any genes coding directly for that will be reinforced. If these genes already exist, this will take a few hundred years. If mutations are needed, it could take 10x longer. Eventually, though, if the selection pressure persists, having babies will have the same pull on female brains as sugar, sex or serotonin-inducing social affirmation. At some point, though, REAL overpopulation is likely to be a limiting factor. Real, as in famine or disease will place a hard cap and re-introduce child mortality rates of 50%+.
  - api 4y ago
    A quote from a prof in college (that he perhaps wouldn’t say today for fear that it might be misinterpreted): “You don’t understand evolution unless you understand how contraception could cause overpopulation.” I do wonder if this falling population in developed countries trend will last more than 1-2 more generations. We’d better have the rockets ready to go by 2100.
    - badpun 4y ago
      Wouldn't it be far easier to colonize Earth ocean floors than to colonize Mars? Both are seem similarly hopeless, but ocean floors seem easier, just because of transportation difficulties alone.
  - jkhdigital 4y ago
    > having a genetic predisposition toward liking sex was enough Maybe re-read that a few times. Is it reasonable to believe that a significant portion of the population would not like sex? Is there any possible evolutionarily-sound explanation for that?

CPLX 4y ago

The hidden variable here is the newly available innovation of birth control pills.

deleted 4y ago
[deleted]
klipt 4y ago
It's just nature's way of filtering out people who like sex but don't want kids. Prior to birth control, having a genetic predisposition toward liking sex was enough. In the future, most people will also have a genetic or cultural disposition towards wanting kids.
- CPLX 4y ago
  > It's just nature's way of filtering out people who like sex but don't want kids. More like: It's just nature's way of filtering out people who like sex but don't want [more] kids [right now]. That’s a lot of people, and thus, less kids.
  - taneq 4y ago
    Taking it to its logical conclusion, it’s nature’s way of filtering out people who either (a) have good short term but poor long term planning, or (b) have good impulse control. Uhoh.
- trashtester 4y ago
  Exactly this. A couple of centuries from now, people will laugh about that time people thought that the population will collapse. Most likely, there is an enormous selection pressure right now for any genes that predispose people (and in particular women) to want to have (many) kids. If those genes are as common as I believe, they should be dominant within about 10 generations (counting from approximately 1970).
  - jkhdigital 4y ago
    And that selection pressure hasn't existed for the entire history of life? I don't think genetics have nearly as much to do with it because we are not living in a "state of nature" where genetics are the dominant factor in reproductive fitness. Even Richard Dawkins recognized this many decades ago when he coined the term "meme" to refer to the units of cultural lineage that clearly influence evolutionary fitness by altering the behavior of the people who hold them. edit: I mean, you're not wrong, but I'd posit that there is enormous selection pressure for memes that promote fertility.
    - trashtester 4y ago
      > And that selection pressure hasn't existed for the entire history of life? Not at all. For most of evolutionary time, organisms didn't even have any kind of cognitive capacity at all (being single celled organisms). Even after brains started to develop, mating behavior was primarily instinctual. And even up until this day in humans, the sexual drive may easily overpower any desire to prevent pregnancy if people (and women in particular) doesn't have access to birth control. Arguably, the sexual drive may have been so strong that there may have been a selection pressure favoring INHIBATION of reproductive behavior (K selection). https://en.wikipedia.org/wiki/R/K_selection_theory https://en.wikipedia.org/wiki/R/K_selection_theory Especially so in females, as under some conditions, having fewer offspring and investing more in each may provide a higher number of surviving offspring than giving birth to more, but with less investment in each. Without birth control, even K-selection strategies ended up with 5 or so offspring per woman, on average, with about 2-3 surviving children on average. With child survival rates near 100%, K-selection strategies are now strongly disfavored compared to r-selection strategies, even without birth control. (So r-selection has probably been selected for at some level for the past 150 years or so in the West). Birth control simply multiplies this effect. > because we are not living in a "state of nature" This, I'm sure, is a fallacy. The rate of genetic adaptation is directly linked to the strength of selection pressures, where "selection pressures" are not just survival rates, but rather the number of surviving offspring. To quote wikipedia: "Contrary to popular belief, not only are humans still evolving, their evolution since the dawn of agriculture is faster than ever before" https://en.wikipedia.org/wiki/Recent_human_evolution https://en.wikipedia.org/wiki/Recent_human_evolution > "meme" to refer to the units of cultural lineage that clearly influence evolutionary fitness by altering the behavior of the people who hold them. Memes (as coined by Dawkins, not the pop culture use) are their own replicators. They code for the replication of thoughts and ideas. Memes are not very tightly coupled to the physical fleshbags they inhabit. Like regular viruses, they often pass from host to host laterally, even though some forms are often transferred to children. But there is no reason to think that this has limited genetic evolution (meaning adaptation, not necessarily "improvement"). This is basically orthogonal to whatever the memes are doing. (Though there is an interaction term where genes and memes form part of the natural environment of each other as replicators). Genes may not be the dominant factor in reproductive fitness right now, but unlike for memes, the relative frequency of genes depend directly on reproductive fitness, meaning whatever variance DOES ALREADY exist in the genome for reproductive fitness are under a massive selection pressure right now. For many, if not most memes, reproductive the reproductive fitness of the hosts has little impact on the ability of the meme to replicate. For some memes (or meme-plexes) like religions, one _could_ argue that they attach themselves strongly enough to families that they are inherited in a way similar to genes. However, I would argue that memes can lose this power much more quickly than genes can. Just consider how quickly Christianity have been losing power over most Western linages lately. Meanwhile, genes will continue to build up momentum for as long as the selection pressure remains. Currently, that pressure is for women to WANT to have children. While cultural effects may come and go, any genes coding directly for that will be reinforced. If these genes already exist, this will take a few hundred years. If mutations are needed, it could take 10x longer. Eventually, though, if the selection pressure persists, having babies will have the same pull on female brains as sugar, sex or serotonin-inducing social affirmation. At some point, though, REAL overpopulation is likely to be a limiting factor. Real, as in famine or disease will place a hard cap and re-introduce child mortality rates of 50%+.
- api 4y ago
  A quote from a prof in college (that he perhaps wouldn’t say today for fear that it might be misinterpreted): “You don’t understand evolution unless you understand how contraception could cause overpopulation.” I do wonder if this falling population in developed countries trend will last more than 1-2 more generations. We’d better have the rockets ready to go by 2100.
  - badpun 4y ago
    Wouldn't it be far easier to colonize Earth ocean floors than to colonize Mars? Both are seem similarly hopeless, but ocean floors seem easier, just because of transportation difficulties alone.
- jkhdigital 4y ago
  > having a genetic predisposition toward liking sex was enough Maybe re-read that a few times. Is it reasonable to believe that a significant portion of the population would not like sex? Is there any possible evolutionarily-sound explanation for that?