4 ms·

I agree that the demographic transition has occurred; I do not think it will last.

brlewis 11y ago
What mechanism do you think will cause it not to last? Why would the same mechanism allow it to occur in the first place? The U.S. had a lot of large families generations ago. This behavior not been generally inherited. What makes you think the future will be different from what we've observed so far?
- Symmetry 11y ago
  Evolution. The propensity to have many children in our current environment was not selected for previously because our species evolution didn't occur in this environment. But it is selected for now.
- WildUtah 11y ago
  We had two massively destructive events that devastated the human population in the twentieth century. The first was the development of reliable birth control and the second was widespread learning about fertility cycles. For the first time, people could be in control of their fertility without celibacy. Our genes programmed us to be mostly unable to be celibate but the allowed us to continue wishing that we could have fewer children so that we could care for them better and not see so many of them crowded in misery and starving. Once reliably vulcanized and molded rubber was practical around 1910, our wish for fewer children could be realized and evolution is slowly breeding out the desire to have a reasonable number of children and stop. The pill and rhythm just intensified the effect. You mostly see evolution in the form of population replacement. Educated and modern Iranians and Egyptians, along with other Middle East and Sahel populations filled up cities and created an Islamic rebirth of learned culture, education, and prosperity in the early and mid 1900s. The people who stayed behind in rural areas continued having eight babies each while the urbanites averaged one. It's amazing to see the photos of free educated modern young men and especially women on the streets of Cairo or Teheran in the 1950s. Those people planned to educate the next generation into modernity but the next generation weren't their children; they were the children of the villages they left behind. Now we have a fertile and intensely fundamentalist, rural, and violent predominant culture in those nations and the renascence exists only in exile populations in the West. European descended populations that plan ahead to have fewer babies are being replaced by more fertile populations from elsewhere across Europe and by native populations in Latin America. Within the USA, you can watch Mormons and fertile evangelicals expand their share of the white population every generation. The demographic transition is a temporary thing. Evolution absolutely demands it. Creationism or Lamarckism is not going to just start being true because it would be convenient to our demographic comfort.
  - selimthegrim 11y ago
    Your argument doesn't hold for Iran today - under the Islamic republic birthrates crashed due to a family planning program and expansion of female higher education, the former which they are now trying to row back a bit.
    - WildUtah 11y ago
      Iranian birth rates started falling rapidly around 1985 which should be counted as a major achievement of the current regime. Still, it was thirty years too late for the post-WWII liberal rebirth of Persian culture to survive. Maybe a return to fundamentalism in Iran was necessary to motivate the people to kick out abusively nasty Western-sponsored dictators, though; that was an ugly period.
  - astazangasta 11y ago
    This demographic picture of the wild rural savages out breeding the cultured urbanites is one possible explanation of why we have fundamentalism now, but I don't find this very compelling. Secular Arabs and Persians were not outbred, they were deposed and shot. The same kids who a generation ago would have been good Marxist PLO members are screaming "Takbir!" and wearing Hamas armbands. I watched this happen in the US around 2003. Culture moves much faster than selection.
    - WildUtah 11y ago
      "Marxist PLO members are screaming "Takbir!" and wearing Hamas armbands. I watched this happen in the US around 2003." You watched US PLO Marxists join Hamas in 2003?
      - astazangasta 11y ago
        I used to hang around with lots of Palestinians at various demos. Around that time (leading up to when Hamas was elected) it became more common to see kids with Hamas armbands, to have kids do Takbir call-and-response, have guys show up with prayer mats. It was a very sudden transition and the reason is obvious: there was a shift in who represented a credible opposition/resistance to American hegemony. Prior to that it was the PLO, still riding the wave of their Soviet-era influence. Now the radicals who were winning victories were Islamists. This is probably all as boring as just being about who has money (Communists then, conservative Saudis now), and thus, ultimately about oil. But I don't think it has much to do with population-level selection.

What mechanism do you think will cause it not to last? Why would the same mechanism allow it to occur in the first place? The U.S. had a lot of large families generations ago. This behavior not been generally inherited. What makes you think the future will be different from what we've observed so far?

Symmetry 11y ago
Evolution. The propensity to have many children in our current environment was not selected for previously because our species evolution didn't occur in this environment. But it is selected for now.
WildUtah 11y ago
We had two massively destructive events that devastated the human population in the twentieth century. The first was the development of reliable birth control and the second was widespread learning about fertility cycles. For the first time, people could be in control of their fertility without celibacy. Our genes programmed us to be mostly unable to be celibate but the allowed us to continue wishing that we could have fewer children so that we could care for them better and not see so many of them crowded in misery and starving. Once reliably vulcanized and molded rubber was practical around 1910, our wish for fewer children could be realized and evolution is slowly breeding out the desire to have a reasonable number of children and stop. The pill and rhythm just intensified the effect. You mostly see evolution in the form of population replacement. Educated and modern Iranians and Egyptians, along with other Middle East and Sahel populations filled up cities and created an Islamic rebirth of learned culture, education, and prosperity in the early and mid 1900s. The people who stayed behind in rural areas continued having eight babies each while the urbanites averaged one. It's amazing to see the photos of free educated modern young men and especially women on the streets of Cairo or Teheran in the 1950s. Those people planned to educate the next generation into modernity but the next generation weren't their children; they were the children of the villages they left behind. Now we have a fertile and intensely fundamentalist, rural, and violent predominant culture in those nations and the renascence exists only in exile populations in the West. European descended populations that plan ahead to have fewer babies are being replaced by more fertile populations from elsewhere across Europe and by native populations in Latin America. Within the USA, you can watch Mormons and fertile evangelicals expand their share of the white population every generation. The demographic transition is a temporary thing. Evolution absolutely demands it. Creationism or Lamarckism is not going to just start being true because it would be convenient to our demographic comfort.
- selimthegrim 11y ago
  Your argument doesn't hold for Iran today - under the Islamic republic birthrates crashed due to a family planning program and expansion of female higher education, the former which they are now trying to row back a bit.
  - WildUtah 11y ago
    Iranian birth rates started falling rapidly around 1985 which should be counted as a major achievement of the current regime. Still, it was thirty years too late for the post-WWII liberal rebirth of Persian culture to survive. Maybe a return to fundamentalism in Iran was necessary to motivate the people to kick out abusively nasty Western-sponsored dictators, though; that was an ugly period.
- astazangasta 11y ago
  This demographic picture of the wild rural savages out breeding the cultured urbanites is one possible explanation of why we have fundamentalism now, but I don't find this very compelling. Secular Arabs and Persians were not outbred, they were deposed and shot. The same kids who a generation ago would have been good Marxist PLO members are screaming "Takbir!" and wearing Hamas armbands. I watched this happen in the US around 2003. Culture moves much faster than selection.
  - WildUtah 11y ago
    "Marxist PLO members are screaming "Takbir!" and wearing Hamas armbands. I watched this happen in the US around 2003." You watched US PLO Marxists join Hamas in 2003?
    - astazangasta 11y ago
      I used to hang around with lots of Palestinians at various demos. Around that time (leading up to when Hamas was elected) it became more common to see kids with Hamas armbands, to have kids do Takbir call-and-response, have guys show up with prayer mats. It was a very sudden transition and the reason is obvious: there was a shift in who represented a credible opposition/resistance to American hegemony. Prior to that it was the PLO, still riding the wave of their Soviet-era influence. Now the radicals who were winning victories were Islamists. This is probably all as boring as just being about who has money (Communists then, conservative Saudis now), and thus, ultimately about oil. But I don't think it has much to do with population-level selection.