If there is some general effect of latitude on IQ, then I would not expect America to look, long-term, like Britain or France. Indeed, I’d expect about half of the US to eventually look like North Africa, and the upper half of the US to look more like Spain, Italy, and Turkey.
The US has historically been a land of great abundance–a land where a small founding population like the Amish might grow from 5,000 people in 1920 to over 290,000 people today.
One of the side effects of abundance has been lower infant mortality; indeed, one of the side effects of modernity has been low infant mortality.
In the Middle Ages, a foundling’s chances of surviving their first year were down around 10%. What did orphanages do without formula? (Goat’s milk, I suspect.) Disease was rampant. Land was dear. Even for the well-off, child mortality was high.
My great-great grandparents lost 6 or 7 children within their first week of life.
Things were pretty harsh. An infant mortality rate of 50% was not uncommon.
American abundance, warm climate, industrialization, and modern medicine/hygiene have all worked together to ensure that far more children survive–even those abandoned by one or more parents. (As someone who would have died 3 or 4 times over in infancy without modern medicine, I am not without some personal appreciation for this fact.)
I recently read an interesting post that I can’t find now that basically posited the theory that all of these extra surviving people running around are depressing the average IQ because they have little sub-optimal bits of genetic code that previously would have gotten them weeded out. There’s a decently strong correlation between intelligence and athleticism–not necessarily at the high end of intelligence, but it does appear at the high end of athleticism. Good athletes are smarter than bad athletes. Smart people, Hawking aside, are generally pretty healthy. For that matter, there are strikingly few fat people at the nation’s top universities. So it is not unreasonable to suspect that a few deleterious mutations that result in some wonky side effects in your kidneys or intestines might also cause some wonky side effects in your brain, which could make you dumber or just really fond of stuffed animals or something.
Okay, but this post is not actually about the theory that low infant mortality is turning us all into furries.
My theory is that America + Modernity => more children of single mothers surviving => long therm changes in marriage/divorce rates => significant long term changes in the structure of society.
Historically, if we go a little further south to Sub-Saharan Africa, monogamy has not been a big thing. Why? Because the climate is generous enough that people don’t have to store up a ton of food for the winter, and women can do most of the food production to feed their children by themselves, or with the help of their extended kin networks. In these places, polygyny is far more common, since men do not need to bear the burden of providing for their own children.
As we head north, the winters get colder and the agricultural labor more intensive, and so the theory goes that women in the north could not provide for their children by themselves. And so Fantine, unwed, dies attempting to provide for her little Cosette, who would have died as well were it not for the ways of novels. The survivors were the men and women who managed to eek out a living together–married, basically monogamous.
But take away the dead Cosettes and Olivers–let them survive in more than just books–and what do we have? Children who, sooner or later, take after their parents. And even if one parent was faithful ’till death, the other certainly wasn’t.
Without any selective pressure on monogamy, monogamy evaporates. So now you can get a guy who has 34 children by 17 different women, and all of the children survive.
Meanwhile, neurotic types who want to make sure they have all of their career and personal ducks all lined up in a row “just can’t afford” a kid until they’re 38, have one if they’re lucky, and then call it quits.
Guess who inherits the future?
Those who show up, that’s who.
I suspect that the effects of low infant mortality have been accumulating for quite a while. Evolution can happen quite quickly if you radically change your selective parameters. For example, if you suddenly start killing white moths instead of grey ones, the moth population will get noticeably darker right after you kill the moths. Future generations of moths will have far fewer white moths. If you then top killing the white moths, white moths will again begin to proliferate. If white moth start having even more babies than grey moths, soon you will have an awful lot of white moths.
Long term, I expect one of the effects of abandoned children surviving is that the gene pool ends up with a lot more people who lack a genetic inclination toward monogamy. At first, these people will just be publicly shamed and life will continue looking relatively normal. But eventually, we should get to a tipping point where we have enough non-monogamous people that they begin advocating as a block and demanding divorce, public acceptance of non-marital sex, etc.
Another effect I would expect is a general “masculinization” of the women. Women who have to fend for themselves and raise their own children without help from their husband have no practical use for femininity, and the more masculine among them will be more likely to thrive. Wilting, feminine flowers will fade away, replaced by tough dames who “need a man like a fish needs a bicycle.”
Only time will tell if the future will belong to the Amish and the Duggers, or to Jay Williams’ progeny.