Very interesting, the bell curve. It make me wonder about how very high IQ communities formed in other parts of the word. This piece suggests cottage industries passed down the generations and could easily apply in many regions.
Cottage industry could drive cognitive evolution where:
1) - the market economy was relatively large and elastic; and
2) - successful entrepreneurs translated their economic success into reproductive success.
Unfortunately, these two conditions were far from universal. The market economy was relatively small and static in most of the world until the past century or so. In addition, successful entrepreneurs in some regions would use their economic success to buy slaves (and slave women as secondary wives).
Something that has held my interest for some time is the increase in cognitive ability, if one uses physics discoveries as a proxy, during the era from, say, 1850 to 1930. Any comments?
The genomic evidence indicates a decline in mean cognitive ability since at least the 1910s. This was the finding of a genomic study of 129,808 Icelanders born between 1910 and 1990 (Kong et al., 2017). A similar decline was found in a genomic study of 11,822 Americans of European ancestry born between 1931 and 1953 (Beauchamp, 2016). The cause was a sharp drop in the fertility of middle-class couples.
Even if the decline in mean cognitive ability had begun c. 1900, it would have become apparent only 30 to 55 years later. Academics tend to peak in their late 30s or early 40s in terms of raw publication counts and in their 40s to early 50s in terms of high‑impact work and major grant success.
Sources:
Beauchamp, J.P. (2016). Genetic evidence for natural selection in humans in the contemporary United States. Proceedings of the National Academy of Sciences, USA, 113, 7774-7779. https://doi.org/10.1073/pnas.1600398113
Kong, A., Frigge, M.L., Thorleifsson, G., Stefansson, H., Young, A.I., Zink, F., Jonsdottir, G.A., Okbay, A., Sulem, P., Masson, G., Gudbjartsson, D.F., Helgason, A., Bjornsdottir, G., Thorsteinsdottir, U., & Stefansson, K. (2017). Selection against variants in the genome associated with educational attainment. Proceedings of the National Academy of Sciences USA, 114(5), E727-E732. https://doi.org/10.1073/pnas.1612113114
"A similar decline was found in a genomic study of 11,822 Americans of European ancestry born between 1931 and 1953 (Beauchamp, 2016). The cause was a sharp drop in the fertility of middle-class couples."
Point of clarity. If there was a drop off in the fertility of middle-class couples, who was responsible for the 'Baby Boom'?
Almost everyone. The baby boom wasn't due to some people having more babies than previously. It was due to more people getting married and having babies.
"... in all western countries during this period, average ages at marriage dropped and the proportions ever marrying increased, the proportions still single at ages 20–25 dropped by 10 percentage points or more in many countries. the proportions ever marrying climbed by 4 to 10 percentage points over the course of 25 birth cohorts, starting from women born around 1910 and reaching unprecedented high levels among women born around 1935."
Van Bavel, J., & Reher, D. S. (2013). The Baby Boom and Its Causes: What We Know and What We Need to Know. Population and Development Review, 39(2), 257-288.
"Were there “hot spots” of unusually strong cognitive evolution? Such hot spots may have arisen wherever cottage industry predominated between the 15th and 19th centuries, particularly in Westphalia, Saxony, the Zurich uplands, Piedmont, Lombardy, Alsace, Flanders, Brittany, Lancashire, Yorkshire, and Ulster. In such areas, semi-rural cottagers enjoyed a population boom due to low mortality and high fertility. On the one hand, they lived away from urban areas, where disease and malnutrition kept population growth in check. On the other, they employed family members in their workshops and had no other means to expand their workforce.
These cottagers produced their wares on contract for urban merchants. They thus operated in an elastic, competitive market, with some doing better than others. Those who did better, had more children — generally by marrying earlier and helping their offspring do likewise (Seccombe, 1992, pp. 205, 217). This translation of economic success into reproductive success must have created strong selection for cognitive ability."
It seems to me that the production of wares on contract is perhaps not the key factor for selection for cognitive ability in this scenario. Rather, it might instead be a matter of a family-corporation, where your children are your labor force, and it's economically rational to procreate insofar as your kids generate economic surplus, or something like that. If so, this argument could also work for e.g. family farms on the American frontier, as described in e.g. the Little House on the Prairie books. (Recall that Jamestown was founded in 1607, so there's a fair amount of overlap in terms of the time period.) Thoughts?
That's a key precondition for cognitive evolution, but it's not a sufficient precondition in and of itself.
In feudal Europe, parents relied on work by their children. There were slaves, but they were few in number, particularly in Western Europe. There was also a belief (often disregarded) that Christians could not be enslaved.
Yet, despite this dependence on child labor, cognitive evolution remained sluggish, if not static. There was a difference in family size between successful artisans and unsuccessful ones, but it was not a big difference. In any case, this embryonic middle class was proportionately very small.
With the transition from feudalism to a market economy, the middle class entered a much more dynamic and volatile economic environment. Goods were now produced on short-term contracts, instead of long-term ones.
"Winners" could thus win a lot more, and "losers" could lose a lot more. A successful "ma and pa" shop could greatly increase production, but the only way to increase their workforce was to have more children, usually by marrying earlier and encouraging their kids to marry early. There was also serial polygyny. One of my ancestors had over twenty kids by three successive wives.
It was this discrepancy between "winners" and "losers" that fueled cognitive evolution in Western Europe from the 14th to 19th centuries. In the 19th century, with the rise of factory capitalism and labor markets, it became easier to hire workers from outside one's family. Hired workers became preferred because they could be hired and fired at will. Consequently, children became a net cost, and the middle class had fewer and fewer of them.
I think the US is interesting as an intermediate case here.
It didn't really have feudalism (at least in the North where the majority of the white people were). Northern farmers used the labor of their kids, Southern farmers did if they couldn't afford slaves.
It *did* have a market economy.
And like Europe after the Black Death, there was a surplus of natural resources relative to population. Side note: As an alternative frame which might be useful, in evolutionary biology, it's common to talk about colonizing vs competing. The phenotype which works best for colonization (greenfield calorie production, low population sizes) is not necessarily the one which works best for competition (system is in Malthusian equilibrium). So one hypothesis related to this discussion, is that the optimal human phenotype for colonization is more IQ-boosted than the optimal human phenotype for competition. Or colonization is more eugenic or whatever. The continental US and Canada was rather sparsely populated by natives, perhaps 1% of its current population density, and that's *before* epidemics swept through. See https://en.wikipedia.org/wiki/Population_history_of_the_Indigenous_peoples_of_the_Americas#Estimations
I suspect rural farming in pre-industrial times was rather cognitively demanding, since trade is limited; low population density means less specialization, more executive decisionmaking per-capita (especially once mechanization starts kicking in the mid-1800s) and you end up making a lot of stuff for yourself around the farm. IIRC, a lot of the Little House on the Prairie books consist of descriptions of pioneer methods for making things that nowadays we would just buy at Target. I also remember reading somewhere that a number of early computer pioneers were farm boys who found that the "systems thinking" mindset from the farm transferred well to early computers.
So the key question seems to be the importance of the long vs short term contract factor. The best farmers are presumably able to translate child labor into cash more effectively than the worst farmers. But how does this affect fertility? My understanding is that the early US had more of an arranged marriage system on the basis of economic prospects, and there were [sometimes] many more men than women due to male-biased immigration, so women could e.g. pick a guy whose parents were prosperous farmers and used their surplus to buy the son a big farm. On the other hand, with land so abundant, acquiring a farm might not be super challenging even if you're a lousy farmer. (And, how does this fit in with the Black Death stuff? Presumably, getting a job after the Black Death is easy even if you're bad at your job, if there's a labor shortage.)
I'm familiar with Crémieux's reasoning. It's difficult to say because there have been demographic changes on both sides of the Atlantic over the past two centuries. War took a heavier toll on Europe than on North America, and the people unfit for military service tended to be less intelligent (among other things). In fact, military service generally requires a certain minimum level of cognitive ability.
There were also various revolutions, which tended to single out those who belonged to the former elite.
As to your points on farming in North America, I was surprised in my research on French Canada to discover that many people who identified as "farmers" to the census-taker had businesses that brought in more income than their farming (i.e., innkeeping, retail trade, etc.) They nonetheless identified as farmers because farming was more prestigious than business. It implied that they owned land.
If post black-death conditions lead to a revolution in thought in the population and economic model than the economically and politically induced social stagnation in the wake of the boomers clinging to power with immigration driving down wages has cannibalized long term social and evolutionary good in the name of short term profit. We were about to hit a Black death-like bottleneck and it's been sabotaged or halted entirely, preventing the genetic development of the species.
Yes, labor scarcity causes a shift to "smarter work." People concentrate on higher-order tasks while eliminating simple tasks through automation, robotization, or simply a more rational use of labor resources.
Labor shortages were a "problem" throughout the postwar era, and employers were grateful when it became easier to import workers after the mid-1960s. Yet the postwar era was a time of rising productivity. Liberalization of immigration has reduced the pressure on employers to find more efficient ways of using labor. The word "liberalize" is itself a misnomer in this context because "liberal" immigration has had the effect of encouraging employers to hang on to old ways of doing things.
Its the same way that slavery halted industrial innovation and intellectual development at the height of Rome, the Ottoman Empire, or even in the American South. Makes life easier for a while but ultimately slavery breeds weakness and complacency.
1- does this apply only to Italy or west Europe in general
2- how big was difference in congenetive ability predicting alleles between the more "civilized" iron age inhabitants of Italy classical Greece and different Greek colonies and Carthage (we have genetic samples from all ) on one hand and iron age inhabitants of France Britain Denmark/Scandinavian countries and the cultural iron age groups of European low lands like Hallstatt and if there was wouldn't gene flow (that with certainty know happen) from the more civilized areas of Europe like Greece Italy and agean towards central Europe and Iberia has the opposite effect?
1. The situation was probably the same throughout the Romanized portions of the Empire. I say this for two reasons:
- The collapse of elite fertility was commented on by a number of contemporary writers throughout the Empire.
- We have genomic data from Greece (unpublished), and it seems to show the same decline in mean cognitive ability during the Imperial Era.
2. The Classical Period stretches from the 8th century BC to the 5th century AD. In my opinion, mean cognitive ability began to decline around the time of Christ. Prior to that, mean cognitive ability was at its peak, and this is probably why there was much more scholarly production during those times than later.
I don't know whether pre-imperial Greece had a cognitive edge over the rest of Europe. A research team is still going through the genomic data from Greece, so we'll have to sit on our hands until they publish their findings. As I said, the preliminary results resemble what we see for central Italy.
But is it statistically significant? I agree that something was happening before the Black Death, but the nature of feudal society acted as a brake on cognitive evolution. There could be no strong selection for cognitive ability as long as the feudal economy persisted.
Feudalism is a static system that discourages change and innovation. Serfs didn't own their land; in fact, they didn't really own themselves. The Lord had the last word on most things.
I don’t have the raw data to see for myself but it seems pretty significant to me. You seem to have a very pessimistic view of feudalism, also feudalism wasn’t a monolith for all of its history. It looks like something happened to me. Just because we don’t have an obvious explanation for something doesn’t mean it didn’t happen.
"Dividing the sample into pre and post Black Death period using 1350 CE as the cutoff date, the statistically significant positive time trend is confined to the post-Black Death period."
I agree that feudalism wasn't a monolith, but there was much less change in the feudal economy than in the market economy. The feudal system, by its very nature, discouraged change. Serfs couldn't make major decisions on land use or use of surplus capital.
Loved reading this and in particular that you connected this to Piaget’s developmental stages. That seems very likely. What I’m wondering, in general, is about the mechanism: is it really just that smarter people were able to have more kids? Because dumb people also seem to have lots of kids too.
Before the late 19th century, poor people were less likely to get married and have children. Even if they had children, they would lose many to early death (usually infections).
All this began to change with the rise of factory capitalism. Poor people could find a single place of employment with regular pay, and more of them could get married. This was also a time when many public hygiene measures were first introduced. Infantile mortality began to decline, particularly among the poor. Later, in the early to mid-20th century, social welfare policies were introduced. It became possible to have children without a husband and without employment income.
Factory capitalism had the opposite effect on the middle-class families. They had less incentive to have kids. If they needed more hands at the factory, they could just hire more workers. There was also peer pressure to send children to prestige schools and buy them expensive clothes, games, etc. Children thus became a net cost, and the middle class reduced its average family size accordingly.
Globalization is a process that began before the discovery of the New World, essentially during the period from 1350 to 1500. Initially, this process involved the replacement of localized market and pre-market economies within Western Europe. This Western world system then expanded overseas, becoming increasingly dominated by Britain and the United States.
Very interesting, the bell curve. It make me wonder about how very high IQ communities formed in other parts of the word. This piece suggests cottage industries passed down the generations and could easily apply in many regions.
Cottage industry could drive cognitive evolution where:
1) - the market economy was relatively large and elastic; and
2) - successful entrepreneurs translated their economic success into reproductive success.
Unfortunately, these two conditions were far from universal. The market economy was relatively small and static in most of the world until the past century or so. In addition, successful entrepreneurs in some regions would use their economic success to buy slaves (and slave women as secondary wives).
Excellent, interesting, and informative article.
Something that has held my interest for some time is the increase in cognitive ability, if one uses physics discoveries as a proxy, during the era from, say, 1850 to 1930. Any comments?
The genomic evidence indicates a decline in mean cognitive ability since at least the 1910s. This was the finding of a genomic study of 129,808 Icelanders born between 1910 and 1990 (Kong et al., 2017). A similar decline was found in a genomic study of 11,822 Americans of European ancestry born between 1931 and 1953 (Beauchamp, 2016). The cause was a sharp drop in the fertility of middle-class couples.
Even if the decline in mean cognitive ability had begun c. 1900, it would have become apparent only 30 to 55 years later. Academics tend to peak in their late 30s or early 40s in terms of raw publication counts and in their 40s to early 50s in terms of high‑impact work and major grant success.
Sources:
Beauchamp, J.P. (2016). Genetic evidence for natural selection in humans in the contemporary United States. Proceedings of the National Academy of Sciences, USA, 113, 7774-7779. https://doi.org/10.1073/pnas.1600398113
Kong, A., Frigge, M.L., Thorleifsson, G., Stefansson, H., Young, A.I., Zink, F., Jonsdottir, G.A., Okbay, A., Sulem, P., Masson, G., Gudbjartsson, D.F., Helgason, A., Bjornsdottir, G., Thorsteinsdottir, U., & Stefansson, K. (2017). Selection against variants in the genome associated with educational attainment. Proceedings of the National Academy of Sciences USA, 114(5), E727-E732. https://doi.org/10.1073/pnas.1612113114
"A similar decline was found in a genomic study of 11,822 Americans of European ancestry born between 1931 and 1953 (Beauchamp, 2016). The cause was a sharp drop in the fertility of middle-class couples."
Point of clarity. If there was a drop off in the fertility of middle-class couples, who was responsible for the 'Baby Boom'?
Almost everyone. The baby boom wasn't due to some people having more babies than previously. It was due to more people getting married and having babies.
"... in all western countries during this period, average ages at marriage dropped and the proportions ever marrying increased, the proportions still single at ages 20–25 dropped by 10 percentage points or more in many countries. the proportions ever marrying climbed by 4 to 10 percentage points over the course of 25 birth cohorts, starting from women born around 1910 and reaching unprecedented high levels among women born around 1935."
Van Bavel, J., & Reher, D. S. (2013). The Baby Boom and Its Causes: What We Know and What We Need to Know. Population and Development Review, 39(2), 257-288.
Thanks again for your reply.
Thanks for your reply.
"Were there “hot spots” of unusually strong cognitive evolution? Such hot spots may have arisen wherever cottage industry predominated between the 15th and 19th centuries, particularly in Westphalia, Saxony, the Zurich uplands, Piedmont, Lombardy, Alsace, Flanders, Brittany, Lancashire, Yorkshire, and Ulster. In such areas, semi-rural cottagers enjoyed a population boom due to low mortality and high fertility. On the one hand, they lived away from urban areas, where disease and malnutrition kept population growth in check. On the other, they employed family members in their workshops and had no other means to expand their workforce.
These cottagers produced their wares on contract for urban merchants. They thus operated in an elastic, competitive market, with some doing better than others. Those who did better, had more children — generally by marrying earlier and helping their offspring do likewise (Seccombe, 1992, pp. 205, 217). This translation of economic success into reproductive success must have created strong selection for cognitive ability."
It seems to me that the production of wares on contract is perhaps not the key factor for selection for cognitive ability in this scenario. Rather, it might instead be a matter of a family-corporation, where your children are your labor force, and it's economically rational to procreate insofar as your kids generate economic surplus, or something like that. If so, this argument could also work for e.g. family farms on the American frontier, as described in e.g. the Little House on the Prairie books. (Recall that Jamestown was founded in 1607, so there's a fair amount of overlap in terms of the time period.) Thoughts?
That's a key precondition for cognitive evolution, but it's not a sufficient precondition in and of itself.
In feudal Europe, parents relied on work by their children. There were slaves, but they were few in number, particularly in Western Europe. There was also a belief (often disregarded) that Christians could not be enslaved.
Yet, despite this dependence on child labor, cognitive evolution remained sluggish, if not static. There was a difference in family size between successful artisans and unsuccessful ones, but it was not a big difference. In any case, this embryonic middle class was proportionately very small.
With the transition from feudalism to a market economy, the middle class entered a much more dynamic and volatile economic environment. Goods were now produced on short-term contracts, instead of long-term ones.
"Winners" could thus win a lot more, and "losers" could lose a lot more. A successful "ma and pa" shop could greatly increase production, but the only way to increase their workforce was to have more children, usually by marrying earlier and encouraging their kids to marry early. There was also serial polygyny. One of my ancestors had over twenty kids by three successive wives.
It was this discrepancy between "winners" and "losers" that fueled cognitive evolution in Western Europe from the 14th to 19th centuries. In the 19th century, with the rise of factory capitalism and labor markets, it became easier to hire workers from outside one's family. Hired workers became preferred because they could be hired and fired at will. Consequently, children became a net cost, and the middle class had fewer and fewer of them.
I think the US is interesting as an intermediate case here.
It didn't really have feudalism (at least in the North where the majority of the white people were). Northern farmers used the labor of their kids, Southern farmers did if they couldn't afford slaves.
It *did* have a market economy.
And like Europe after the Black Death, there was a surplus of natural resources relative to population. Side note: As an alternative frame which might be useful, in evolutionary biology, it's common to talk about colonizing vs competing. The phenotype which works best for colonization (greenfield calorie production, low population sizes) is not necessarily the one which works best for competition (system is in Malthusian equilibrium). So one hypothesis related to this discussion, is that the optimal human phenotype for colonization is more IQ-boosted than the optimal human phenotype for competition. Or colonization is more eugenic or whatever. The continental US and Canada was rather sparsely populated by natives, perhaps 1% of its current population density, and that's *before* epidemics swept through. See https://en.wikipedia.org/wiki/Population_history_of_the_Indigenous_peoples_of_the_Americas#Estimations
I suspect rural farming in pre-industrial times was rather cognitively demanding, since trade is limited; low population density means less specialization, more executive decisionmaking per-capita (especially once mechanization starts kicking in the mid-1800s) and you end up making a lot of stuff for yourself around the farm. IIRC, a lot of the Little House on the Prairie books consist of descriptions of pioneer methods for making things that nowadays we would just buy at Target. I also remember reading somewhere that a number of early computer pioneers were farm boys who found that the "systems thinking" mindset from the farm transferred well to early computers.
So the key question seems to be the importance of the long vs short term contract factor. The best farmers are presumably able to translate child labor into cash more effectively than the worst farmers. But how does this affect fertility? My understanding is that the early US had more of an arranged marriage system on the basis of economic prospects, and there were [sometimes] many more men than women due to male-biased immigration, so women could e.g. pick a guy whose parents were prosperous farmers and used their surplus to buy the son a big farm. On the other hand, with land so abundant, acquiring a farm might not be super challenging even if you're a lousy farmer. (And, how does this fit in with the Black Death stuff? Presumably, getting a job after the Black Death is easy even if you're bad at your job, if there's a labor shortage.)
BTW, Crémieux argues that whites in the US and New Zealand outperform on standardized tests, and this is due to selection rather than on-site evolution. https://xcancel.com/cremieuxrecueil/status/1822296863879450861
Note that I myself am a white American so that bias may be affecting my thoughts on this topic.
I'm familiar with Crémieux's reasoning. It's difficult to say because there have been demographic changes on both sides of the Atlantic over the past two centuries. War took a heavier toll on Europe than on North America, and the people unfit for military service tended to be less intelligent (among other things). In fact, military service generally requires a certain minimum level of cognitive ability.
There were also various revolutions, which tended to single out those who belonged to the former elite.
As to your points on farming in North America, I was surprised in my research on French Canada to discover that many people who identified as "farmers" to the census-taker had businesses that brought in more income than their farming (i.e., innkeeping, retail trade, etc.) They nonetheless identified as farmers because farming was more prestigious than business. It implied that they owned land.
If post black-death conditions lead to a revolution in thought in the population and economic model than the economically and politically induced social stagnation in the wake of the boomers clinging to power with immigration driving down wages has cannibalized long term social and evolutionary good in the name of short term profit. We were about to hit a Black death-like bottleneck and it's been sabotaged or halted entirely, preventing the genetic development of the species.
Yes, labor scarcity causes a shift to "smarter work." People concentrate on higher-order tasks while eliminating simple tasks through automation, robotization, or simply a more rational use of labor resources.
Labor shortages were a "problem" throughout the postwar era, and employers were grateful when it became easier to import workers after the mid-1960s. Yet the postwar era was a time of rising productivity. Liberalization of immigration has reduced the pressure on employers to find more efficient ways of using labor. The word "liberalize" is itself a misnomer in this context because "liberal" immigration has had the effect of encouraging employers to hang on to old ways of doing things.
Its the same way that slavery halted industrial innovation and intellectual development at the height of Rome, the Ottoman Empire, or even in the American South. Makes life easier for a while but ultimately slavery breeds weakness and complacency.
I have questions regarding imperial era stuff :
1- does this apply only to Italy or west Europe in general
2- how big was difference in congenetive ability predicting alleles between the more "civilized" iron age inhabitants of Italy classical Greece and different Greek colonies and Carthage (we have genetic samples from all ) on one hand and iron age inhabitants of France Britain Denmark/Scandinavian countries and the cultural iron age groups of European low lands like Hallstatt and if there was wouldn't gene flow (that with certainty know happen) from the more civilized areas of Europe like Greece Italy and agean towards central Europe and Iberia has the opposite effect?
1. The situation was probably the same throughout the Romanized portions of the Empire. I say this for two reasons:
- The collapse of elite fertility was commented on by a number of contemporary writers throughout the Empire.
- We have genomic data from Greece (unpublished), and it seems to show the same decline in mean cognitive ability during the Imperial Era.
2. The Classical Period stretches from the 8th century BC to the 5th century AD. In my opinion, mean cognitive ability began to decline around the time of Christ. Prior to that, mean cognitive ability was at its peak, and this is probably why there was much more scholarly production during those times than later.
I don't know whether pre-imperial Greece had a cognitive edge over the rest of Europe. A research team is still going through the genomic data from Greece, so we'll have to sit on our hands until they publish their findings. As I said, the preliminary results resemble what we see for central Italy.
That sharp increase between 1000 and 1250 is certainly interesting.
But is it statistically significant? I agree that something was happening before the Black Death, but the nature of feudal society acted as a brake on cognitive evolution. There could be no strong selection for cognitive ability as long as the feudal economy persisted.
But actually, why not ? I guess compared to antique slavery and latifundia type farms, the feudal peasantry would be selected for intelligence ?
Feudalism is a static system that discourages change and innovation. Serfs didn't own their land; in fact, they didn't really own themselves. The Lord had the last word on most things.
I don’t have the raw data to see for myself but it seems pretty significant to me. You seem to have a very pessimistic view of feudalism, also feudalism wasn’t a monolith for all of its history. It looks like something happened to me. Just because we don’t have an obvious explanation for something doesn’t mean it didn’t happen.
It doesn't seem to be significant:
"Dividing the sample into pre and post Black Death period using 1350 CE as the cutoff date, the statistically significant positive time trend is confined to the post-Black Death period."
I agree that feudalism wasn't a monolith, but there was much less change in the feudal economy than in the market economy. The feudal system, by its very nature, discouraged change. Serfs couldn't make major decisions on land use or use of surplus capital.
Loved reading this and in particular that you connected this to Piaget’s developmental stages. That seems very likely. What I’m wondering, in general, is about the mechanism: is it really just that smarter people were able to have more kids? Because dumb people also seem to have lots of kids too.
Before the late 19th century, poor people were less likely to get married and have children. Even if they had children, they would lose many to early death (usually infections).
All this began to change with the rise of factory capitalism. Poor people could find a single place of employment with regular pay, and more of them could get married. This was also a time when many public hygiene measures were first introduced. Infantile mortality began to decline, particularly among the poor. Later, in the early to mid-20th century, social welfare policies were introduced. It became possible to have children without a husband and without employment income.
Factory capitalism had the opposite effect on the middle-class families. They had less incentive to have kids. If they needed more hands at the factory, they could just hire more workers. There was also peer pressure to send children to prestige schools and buy them expensive clothes, games, etc. Children thus became a net cost, and the middle class reduced its average family size accordingly.
Globalization is a process that began before the discovery of the New World, essentially during the period from 1350 to 1500. Initially, this process involved the replacement of localized market and pre-market economies within Western Europe. This Western world system then expanded overseas, becoming increasingly dominated by Britain and the United States.