I wrote up a draft post, focusing on heritability; any thoughts before I publish it? I’m especially curious why you think evolution is too slow—if there’s already significant variation within humanity, and we’re in a new period than started recently with birth control + sex ed + lower taboos, it seems to me like it could be just a few generations before people with genetically higher desires for having their own children are having a large fraction of the kids?
My money is on a non-insignificant period of depopulation.
I’d bet on that too—I just think it’s way less than 300y, and we only see modest drops before reversal.
I disagree with this point about financial costs. The cross-section and time-series evidence that richer places and times have fewer children is too hard to square with that claim, in my opinion.
I think my point on housing was wrong—in places with declining populations a more typical pattern is probably that less desirable areas, with the least economic opportunity, depopulating faster. So there’s still expensive housing in places where you can get good jobs, and prospective parents still face large costs if they choose to have kids.
most people I know who don’t have kids wouldn’t press the button
But (a) your non-parent friends may not be the marginal parent and (b) some people would probably now press the button dozens of times.
Robo-nannies or something that made a serious dent in the time parents felt they should spend with their kids seems like a more important margin to me.
My impression is this as well, but more as a cost issue and not a time issue. Childcare is very expensive (it’s our family’s largest expense, with three kids), and automation might be able to help with that? Not sure.
Great—glad you wrote that post up on intergenerational dynamics (and remarkably quickly!). I haven’t read through the details in a while, but I think the best paper I’ve seen trying to estimate heritability at the family-level is this one by Tom Vogl, which you might find interesting to dig into. I believe his headline finding is that in low fertility settings that this composition effect accounts for fertility rates being ~4% higher in this generation than it would otherwise be (but that’s just a refresher from my quick skim just now).
My skepticism about evolution is skepticism about the existing variance in biological preferences for children. Obviously that’s not something we can easily get at, since outcomes are the product of environment + constraints + culture + preferences, etc. But (1) this preference isn’t currently common enough to push some economically developed countries above replacement rate and (2) once social/​economic conditions that generate low-fertility stabilize, this sort of mental-model would always predict increasing fertility rates (since every generations composition becomes more favorable to high-fertility). I’m not sure there’s even a single country with moderate to low fertility that’s seen an increase over the last 10-20 years, even though the demographic transition occurred in some countries a few generations ago. (And we only have a few more, ~7-10, generations worth of time until we’re at pretty low population levels).
Though I’m happy to admit that this is hard to generate convincing evidence on, so maybe in a few more generations it could start to show up in aggregate numbers. But until there’s a country or two with consistent increases in fertility, through policy or evolution or whatever, I will remain very concerned that the decline will not be self-correcting.
Don’t have much to add on the other points you made :)
Thanks!
I wrote up a draft post, focusing on heritability; any thoughts before I publish it? I’m especially curious why you think evolution is too slow—if there’s already significant variation within humanity, and we’re in a new period than started recently with birth control + sex ed + lower taboos, it seems to me like it could be just a few generations before people with genetically higher desires for having their own children are having a large fraction of the kids?
I’d bet on that too—I just think it’s way less than 300y, and we only see modest drops before reversal.
I think my point on housing was wrong—in places with declining populations a more typical pattern is probably that less desirable areas, with the least economic opportunity, depopulating faster. So there’s still expensive housing in places where you can get good jobs, and prospective parents still face large costs if they choose to have kids.
But (a) your non-parent friends may not be the marginal parent and (b) some people would probably now press the button dozens of times.
My impression is this as well, but more as a cost issue and not a time issue. Childcare is very expensive (it’s our family’s largest expense, with three kids), and automation might be able to help with that? Not sure.
Great—glad you wrote that post up on intergenerational dynamics (and remarkably quickly!). I haven’t read through the details in a while, but I think the best paper I’ve seen trying to estimate heritability at the family-level is this one by Tom Vogl, which you might find interesting to dig into. I believe his headline finding is that in low fertility settings that this composition effect accounts for fertility rates being ~4% higher in this generation than it would otherwise be (but that’s just a refresher from my quick skim just now).
My skepticism about evolution is skepticism about the existing variance in biological preferences for children. Obviously that’s not something we can easily get at, since outcomes are the product of environment + constraints + culture + preferences, etc. But (1) this preference isn’t currently common enough to push some economically developed countries above replacement rate and (2) once social/​economic conditions that generate low-fertility stabilize, this sort of mental-model would always predict increasing fertility rates (since every generations composition becomes more favorable to high-fertility). I’m not sure there’s even a single country with moderate to low fertility that’s seen an increase over the last 10-20 years, even though the demographic transition occurred in some countries a few generations ago. (And we only have a few more, ~7-10, generations worth of time until we’re at pretty low population levels).
Though I’m happy to admit that this is hard to generate convincing evidence on, so maybe in a few more generations it could start to show up in aggregate numbers. But until there’s a country or two with consistent increases in fertility, through policy or evolution or whatever, I will remain very concerned that the decline will not be self-correcting.
Don’t have much to add on the other points you made :)
Thanks! Published the post.