That seems dubious. One of the tallest peoples of the world live in the Dinaric Alps. Not the most accessible place.

this is a single variable model. it’s just stupid to conceive of it as so. that was kind of the point of my post, you have be really careful and not turn the model into a ‘toy’. so you’re comparing two different situations. what you need to do is compare the same region over time. there are probably some genetic potential differences in height across populations. this seems clear for the pgymies of central africa from the most recent genetic work.

And Africans, who are perhaps the same height as Euros, are not noted for their road-building skills. Some Sudanese groups have average heights exceeding 6 ft, and I can see on your map that Sudan is one of the hot spots for consanguinity.

you should work on your map-reading skills. or improve your knowledge base. sudan is not culturally homogeneous, as someone who follows the news might be cognizant of. even ignoring point #1 (there are other variables than just inbreeding), the northern sudanese muslims will probably have higher cousin marriage rates because of the norms among arabs and aspirant arabs.

For the Africans appearing normal height, although there is much consanguinity there is actually much more variation in the genome of Africans compared to the average non-African, as non-African genetic diversity only represents a subset of that outside of Africa. I haven’t thought this all through very well and would appreciate further clarification from others, but I suppose that a high amount of consanguinity in a population with high genetic diversity could lead to more genetic variation in individuals than a population that has low consanguinity but has little variation in both population anyway, so even population admixture doesn’t introduce much variation. You have to consider the variation that exists between the populations as well as the amount of admixture between them. If two neighbouring populations share all the same genetic diversity, then it doesn’t matter if you marry someone from ‘your’ or ‘their’ population, the labels are meaningless.

i’d need to look at the numbers for this, but i don’t think the high variance within african matters so much for inbreeding. remember, inbreeding is a problem because near kin carry many of the same negative recessive alleles. it doesn’t matter matter if you have a more varied set or not. there may be some dampening effect though if the population has higher heterozygosity, period, but i wouldn’t bet on it.

I’m wondering if changes from the extreme ends of the endogamy-exogamy spectrum could be very dramatic. If the human norm, through geography, poor transport etc, was very high consanquinity then the first few generations of greater exogamy might show very large drops with continuing but diminishing returns on later generations.

It could potentially work the other way too, for example take an initially relatively exogamous population in a steel town which closes down and the people there decay into an underclass. One aspect of the welfare underclass is the collapse of marriage and monogamy with women having children from multiple fathers and no-one really knowing who they’re related too, or rather it becoming too complicated to calculate except in the closest degrees.

Effectively after a few generations like this (and generations in these kind of contexts are closer to 15 years than 25) everyone living within each segment of those kind of closed environment is having children with (at least) cousins. People from that kind of background do seem to be getting shorter but i put it down to nutrition.

So i wonder if the percentage change in consanquinity when first moving from either of the two extremes could be dramatic.

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“Height ~ Genetic endowment + Environmental contingencies – Incest decrement”

Removing a decrement by greater exogamy sounds more plausible on the face, especially if some of those trial populations in Poland were from once very remote and rural populations.

If it’s true and if the above point re dramatic percentage changes in the first few generations is also true then given some of the dramatic changes post-WWII there ought to be examples of this all over the place (outside the original industrial nations) particularly among what you might call the new elite i.e. not the old aristocracy but the newly emergent larger middle class in places like India and China. If the above is true they ought to be getting taller with possibly larger jumps among the first few generations – although difficult to separate this out from nutrition.

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There’s a tie-in here with the idea of aristocratic in-breeding. Although the peasants existed in much greater numbers in total each village’s marrying pool may have been quite small as a product of an inability to travel. So although the aristocracy had smaller total numbers their marrying pool might actually have been much larger.

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Another thought that comes to mind is a possible connection to the Flynn effect.

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“That seems dubious. One of the tallest peoples of the world live in the Dinaric Alps. Not the most accessible place.”

If this is a general rule, and maybe it isn’t, then one possible cause for exceptions would be peoples who had developed in one environment getting pushed into mountains by invaders.

Another possibility might be particular diets outweighing any in-breeding effect i.e. a diet unusually high in protein. Maybe the Dinaric Alpine people live exclusively on milk?

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“And Africans, who are perhaps the same height as Euros”

Are they?

http://en.wikipedia.org/wiki/Human_height

For the Africans appearing normal height, although there is much consanguinity there is actually much more variation in the genome of Africans compared to the average non-African, as non-African genetic diversity only represents a subset of that outside of Africa. I haven’t thought this all through very well and would appreciate further clarification from others, but I suppose that a high amount of consanguinity in a population with high genetic diversity could lead to more genetic variation in individuals than a population that has low consanguinity but has little variation in both population anyway, so even population admixture doesn’t introduce much variation. You have to consider the variation that exists between the populations as well as the amount of admixture between them. If two neighbouring populations share all the same genetic diversity, then it doesn’t matter if you marry someone from ‘your’ or ‘their’ population, the labels are meaningless.

And Africans, who are perhaps the same height as Euros, are not noted for their road-building skills. Some Sudanese groups have average heights exceeding 6 ft, and I can see on your map that Sudan is one of the hot spots for consanguinity.