french canadians still evolving

(~_^)

i haven’t had a chance to read the research article yet, but here from nicholas wade in the nyt:

“Natural Selection Leaves Fresh Footprints on a Canadian Island”

“From parish records in a French-Canadian island, researchers have uncovered what may be the most recent known instance of human evolution in response to natural selection.

“The island, Île aux Coudres, lies in the St. Lawrence River 50 miles northeast of Quebec. Its church registries hold an unusually complete record of births, marriages and deaths. From this data, a team of researchers led by Emmanuel Milot and Denis Réale of the University of Quebec at Montreal have extracted the histories of women born on the island between 1799 and 1940.

“Over this 140-year period, the age at which a woman had her first child — a trait that is highly heritable — fell to 22 years, from 26. Because of this change, women on average had four more children during their reproductive lifetime, the researchers report.

“The finding ‘supports the idea that humans are still evolving,’ the researchers write in Monday’s issue of The Proceedings of the National Academy of Sciences.”

cool!

but wait! there’s more:

“Dr. Milot said the genetic changes in his study showed up so clearly because other factors that might cloud them had been held to a minimum by the particular social conditions on Île aux Coudres. The island was granted by royal decree to the priests who managed the Quebec seminary and was settled by 30 families who arrived between 1720 and 1773. The families took up farming, then other professions, like fishing. Throughout the period, considerable equality was maintained, and the population lacked the gradations of wealth that can influence who has how many children.

Also, because most people married locally, the island’s population became considerably inbred, despite a ban on marrying first or second cousins.

“These two factors, and the homogeneity of the population, left the field open for genetic effects to become prominent, Dr. Milot said.”

inbreeding?! wait, wait, wait. of course this somewhat isolated population could’ve evolved faster ’cause they were homogeneous so the “genetic effects” could more quickly “become prominent.” but couldn’t it be that they just had more babies ’cause they were inbreeding?! (or maybe the two are the same thing….)

i gotta go look at the research article.

(see, françois? a post about french canadians! at least one sub-group of you guys anyway. (^_^) )

see also: amish paradise from greg cochran.

(note: comments do not require an email. i <3 canada!)

13 Comments

  1. Merci :)

    There’s a great movie called “Pour la suite du monde”[For The Ones to Come] where, for the purpose of the film, old-timers from Île-aux-Coudres were persuaded to revive a local whale-catching practice.

    http://www.nfb.ca/film/pour_la_suite_du_monde_en/ (English subtitles)

    “a trait that is highly heritable”

    Is the same true also for men? I’m from a long line of late bloomers. I’m 29 and my great-grandfather was born in 1853.

    Reply

  2. I remember some commenter at Sailer’s blog talked about how all the French-Canadians are heavily inbred.. he made some amazing claim that they were descended from the same few hundred colonists who first arrived

    doesn’t pass the smell test to me (what, one or two ships travelled to Quebec over all those years of colonization? come on…) but then what do I know about French colonization… not much.

    I suspect it’s a situation of how every British American has an ancestor from the Mayflower or how everyone in Europe is descended from Charlamagne by some insignificantly distant and tiny connection.

    cool study though

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  3. I am unconvinced. This could easily be a wealth or cultural change. Nothing presented shows genetic cause. If this happened in, say, 13th century England, we would assume plague deaths offered more land for producing babies…..

    S. Pengler

    Reply

  4. @luke – “How do you find all this cool stuff?”

    this story i actually found in that wonderful british tabloid, the daily mail. (^_^) i googled the researcher’s name, and then found that greg cochran had already blogged it. (since i’ve been checking out harpending & cochran’s new blog everyday, i guess i would’ve eventually come across it that way. (^_^) )

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  5. @francois – “There’s a great movie called ‘Pour la suite du monde’ [For The Ones to Come] where, for the purpose of the film, old-timers from Île-aux-Coudres were persuaded to revive a local whale-catching practice.”

    neat! that sounds like it’s right up my alley. thnx!

    @francois – “Is the same true also for men? I’m from a long line of late bloomers. I’m 29 and my great-grandfather was born in 1853.”

    apparently not — at least not in finns. whether or not what is true of finns is true of the rest of us … who knows? (~_^)

    btw — thnx for bringing to my attention the fact that french canadians had such a small founding population. i never knew that before you mentioned it here previously. now i’m keen on learning more about you guys! (^_^)

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  6. @bleach – “I remember some commenter at Sailer’s blog talked about how all the French-Canadians are heavily inbred.. he made some amazing claim that they were descended from the same few hundred colonists who first arrived.”

    well, it wasn’t a few hundred, but apparently the number of french settlers to quebec was ca. 5000 (<< opens pdf). that's not a great number, really!

    Reply

  7. @s. pengler – “I am unconvinced. This could easily be a wealth or cultural change. Nothing presented shows genetic cause.”

    well, the researchers have concluded that it was not culture — not in this case anyway. from the research article:

    “Finally, cultural transmission of fitness (CTF) can cause nongenetic inheritance in human traits, and was documented in the nearby Saguenay-Lac-St-Jean French-Canadian population (46). However, we would have expected CTF to be partly reflected in family effects, which again were negligible in all of our analyses.”

    here’s a link (opens pdf) to that research on saguenay-lac-st-jean.

    unfortunately, i can’t evaluate whether the current work done on the population of Île-aux-Coudres is valid or not. they used some sort of bayseian something-or-other statistics and, well, they lost me before they ever got started. they do note, tho, that their methodology has some potential problems, but like i said, i’m not the one to evalute those problems:

    “Crucially, the above conclusion relies on the reliability of PBVs [predicted breeding values]. Here we used a Bayesian analysis intended to avoid the anticonservatism characterizing previous tests of microevolution (23, 24). One potential issue with this approach is its sensitivity in the choice of prior distributions for variance parameters (41). However, the test of microevolution in AFR was robust for various weakly to moderately informative priors. Another potential problem is that when limited information from relatives is available or when relatives share similar environments, PBVs can grasp part of the variation due to nongenetic sources (24, 42). However, the animal model is robust to this kind of bias when supplied with deep and intricate pedigrees because it uses all degrees of relatedness among individuals to estimate genetic parameters. In addition, nongenetic sources of variation can be accounted for explicitly. Here we controlled for temporal trends in traits that might arise from other causes than a change in BVs (24) and for shared familial environment effects that could bias heritability estimates. Actually, there is accumulating evidence that PBVs measured from such multigenerational pedigrees are measuring genetic effects (e.g., 43).”

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  8. hmm. Allow me to counter this: females can give birth (easily) at 15. this measures the age of first birth in practice, not theory. I cannot see any reason for this to be ANYthing other than culture. Is there even a disease that puts back first birth? (I know PCOS would, I guess, as producing eggs is harder, so it would, on average, take longer). Anything else?

    I don’t mean to sound anti-science, I know that is passe now, but I expect this to get ignored/found to be wrong/un-replicatable.

    Basically, when I was in grade 8, a girl in my class got pregnant. I grade nine, 2 did. and about 2-4 a year after that. And, as far as I can tell, the only thing that stopped the rest from doing it was birth control (brought in from fear of ostracization, parents, babies, etc).

    Pengler

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  9. @s. pengler – “I cannot see any reason for this to be ANYthing other than culture. Is there even a disease that puts back first birth? (I know PCOS would, I guess, as producing eggs is harder, so it would, on average, take longer). Anything else?”

    personality traits, which are highly heritable. they can obviously be selected for — imagine a crowded europe where timidity would pay off more than more histrionic-types. then you could have large majorities putting off mating. but, when times are better — when you move to a new environment where there’s plenty of space and resources — more wild-and-crazy personality types might thrive.

    but, you make a very good point. culture sounds like a likely candidate and the authors did consider it. they ruled it out for some mathematical reason that, as per usual, went right over my head.

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  10. @s. pengler – “I don’t mean to sound anti-science, I know that is passe now….”

    you’re allowed to sound anti-science around here! (^_^) especially when you question findings … which is actually quite … scientific in thinking, really. (more scientists should do so.) (^_^)

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  11. @s. pengler – “I cannot see any reason for this to be ANYthing other than culture. Is there even a disease that puts back first birth? (I know PCOS would, I guess, as producing eggs is harder, so it would, on average, take longer). Anything else?”

    personality traits, which are highly heritable. they can obviously be selected for — imagine a crowded europe where timidity would pay off more than more histrionic-types. then you could have large majorities putting off mating. but, when times are better — when you move to a new environment where there’s plenty of space and resources — more wild-and-crazy personality types might thrive.

    but, you make a very good point. culture sounds like a likely candidate and the authors did consider it. they ruled it out for some mathematical reason that, as per usual, went right over my head.

    Well let me try a less mathematical approach. During the Early modern period, common people delayed marriage until they had the resources to start a household. In about 1600 that meant women and men were getting married at say 26+ (I think 28 for men). This would have been the cultural expectations of the time. Now tied to heritability and the Ile aux Coudres.

    Getting married takes resources. Ability to get resources rests on natural talent (skills, IQ, etc) things which are highly heritable, and on environmental factors, like the end of the Little Ice Age meaning the ability to grow more food – remember until 1910 in the US 1/2 of the population was rural. I imagine in Canada, it was later, And to the point I’m trying to make, most of the people on the island were probably working occupations tied to food production. So the end of the LIA means the probability that more food was available.
    So those more successful at getting resources at a younger age, married younger, bringing the age down from 26 to 22. This does not mean they couldn’t become pregnant at 15 or 16, just that cultural norms prevented much out of wedlock birth, and that everyone else following the normal path would be at after marriage.
    So we are looking at 1 outcome (age of mother at first child) and discussing 2 different issues. The biological capacity, and the social expectations. Both are heritable, but one is more explicitly dependent on bio-chemistry than the other. I’d suspect the authors are making the claim based on the heritability of the social aspects over the absolute biological factors (ok technically the nutrition of a person would affect the start of menses, but I’m lumping that under biology, and assuming that it happened well before marriage)

    Reply

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