Long-term trends in human body size track regional variation in subsistence transitio

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https://www.pnas.org/doi/10.1073/pnas.2209482119
[h=2]Significance[/h]The transition from foraging to herding and farming influenced human health, but the impact of regional differences in trajectories of cultural change on human biology are poorly resolved. We investigate long-term trends in human stature and body mass of 3,507 skeletons from 366 archaeological sites in seven regions with varying trajectories of Holocene subsistence change. We observe declines in body size that preceded the transition to agriculture, and significant regional variation following the transition. Holocene statures and body mass remained relatively stable in primary regions of domestication; however, in areas such as Central and Northern Europe where non-native crops were difficult to establish, increases in stature and body mass coincide with the timing of selective sweeps for lactase persistence.
[h=2]Abstract[/h]Evidence for a reduction in stature between Mesolithic foragers and Neolithic farmers has been interpreted as reflective of declines in health, however, our current understanding of this trend fails to account for the complexity of cultural and dietary transitions or the possible causes of phenotypic change. The agricultural transition was extended in primary centers of domestication and abrupt in regions characterized by demic diffusion. In regions such as Northern Europe where foreign domesticates were difficult to establish, there is strong evidence for natural selection for lactase persistence in relation to dairying. We employ broad-scale analyses of diachronic variation in stature and body mass in the Levant, Europe, the Nile Valley, South Asia, and China, to test three hypotheses about the timing of subsistence shifts and human body size, that: 1) the adoption of agriculture led to a decrease in stature, 2) there were different trajectories in regions of in situ domestication or cultural diffusion of agriculture; and 3) increases in stature and body mass are observed in regions with evidence for selection for lactase persistence. Our results demonstrate that 1) decreases in stature preceded the origins of agriculture in some regions; 2) the Levant and China, regions of in situ domestication of species and an extended period of mixed foraging and agricultural subsistence, had stable stature and body mass over time; and 3) stature and body mass increases in Central and Northern Europe coincide with the timing of selective sweeps for lactase persistence, providing support for the “Lactase Growth Hypothesis.”

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Interesting.

"Recent evidence suggests that selection for LP in Central and Northern Europe may have been in response to famine or pathogen exposure, and the pattern of LP persistence alleles reflected in ancient DNA (aDNA) corresponds with incident solar radiation (46), patterns which may be explained in relation to the challenges of establishing crop species at higher latitudes (52) or increased prevalence of zoonotic diseases (53, 54). "
 
^^We're all still missing something, but I can't figure out what it is. Neolithic people had been consuming cheese and probably fermented yoghurt for thousands of years. Why wasn't that enough? Why did they have to start drinking milk? Plus, in those days cattle only calved what, once a year, so what about the rest of the year?

In my own area of Italy there was historically not enough flat or even semi-flat land for cattle, and sheep had to substitute. We may not have lived well, but we survived on fish, game, wild foraged plants and fruits, which were mostly available year-round, and sheep's milk cheese, or pecorino. Later, thanks to the Romans we had chestnuts, bread and pasta made from chestnut flour to supplement expensive wheat, olive oil for good fats, and grapes for wine. Even in the middle of the plague, which devastated us, with sometimes 40% dying, we didn't have cows whose milk we could drink, so maybe that's why there was no selection for it?

Maybe the famine was so terrible or the climate so inhospitable that they didn't have these other nutritional sources?
 
The way the authors described LP spread, makes you think there were times when only milk drinkers survived.

Milk is also a fluid source, useful when drinking water is not available or is contaminated. The more processed the product becomes, the more water it tends to lose. I guess this explains high LP in Arabian Peninsula and East Africa, as seen on this map from Wikipedia.

AAF318FD-7D86-4DEC-A7FD-F68C9B27BB63.jpg

Cows actually lactate for almost a year, sheep and goats for multiple months. It is possible to time the pregnancies in the herd so that milk is available at all times.

There are also some theories that drinking milk increases immunity. And there’s increased calcium absorption with lactose that probably doesn’t apply to processed dairy products.

What is the consumption of any sort of dairy products in societies that are mostly lactose intolerant?
 
If you're talking about "milk immunity", that's the immunity which baby humans get from the mother's, i.e. human milk. Cow milk is for baby cows. That's why many women, like me, chose to nurse their babies.

Bovine milk "contains both immunoglobulins A and G, but in contrast to human milk where IgA is the most abundant, IgG is more abundant.[4]Secretory Component, IgM, both anti-inflammatory and inflammatory cytokines, and other proteins with antimicrobial functions are also present in bovine milk.
[3]"


There are no inflammatory agents in human milk.

You're right about the calcium in milk, but plain yoghurt contains more calcium than an equal amount of milk, and one 1.5 ounce serving of mozzarella provides more calcium than a glass of milk. The calcium is concentrated in the cheese making.

There's also lots of calcium in sardines, salmon etc., with the added benefit of Vitamin D, and also in greens like spinach, kale, and nuts like almonds.

The Chinese and other east Asians are very lactose intolerant, and it doesn't seem to have hurt their population numbers. :) Fish and shell fish and green vegetables seem to be enough. In the coastal Liguria of old it was the same, although they also had cheese and even butter occasionally.

As for dairying, I thought I recalled a paper (although I can't find it now) which stated that the cows of the Bronze and Iron Age did not produce the amount of milk produced by modern cows. Even the teats were much smaller, and that, as my father's family did in the Appennines, cows, where the gestation period is 10 months, were bred in the summer and calved in the spring. They were milked until late fall, but not later, because there wasn't enough grass to support lactation. Of course, things are different now, and they buy hay to run their dairy farm.

Still, with all these changes, I read somewhere that in the "off" season in the U.S. we still import a lot of milk from the Southern Hemisphere.

In terms of the hypothesis that lactose tolerance rose through selection in northern Europe more than in Southern Europe because of famine I suppose a little milk is better than nothing, but I still don't understand the "nature" of the famine. I'm assuming the famine was because crops failed. If crops fail because of drought or overuse so does grass for grazing, so the cows wouldn't produce milk, would they, or at least not in the winter months? Why also would you drink the milk rather than making cheese from it. Liquid cows milk can get contaminated very easily; it was the cause of a lot of infant death in the Victorian Age, for example.
 
There are conditions when grasses thrive and grains fail, like very rainy harvest times that cause the grain to sprout or not stand up any more. Or hot and dry summers when the grain doesn’t grow. Grasses are much more resilient and I’m guessing haymaking was discovered in the higher latitudes along with domestication.

There is an article focusing on this from last summer, not sure if we’ve discussed that.

[URL="https://www.nature.com/articles/s41586-022-05010-7"]Dairying, diseases and the evolution of lactase persistence in Europe


https://www.nature.com/articles/s41586-022-05010-7[/URL]


“We propose that lactase non-persistent individuals consumed milk when it became available but, under conditions of famine and/or increased pathogen exposure, this was disadvantageous, driving LP selection in prehistoric Europe.”

On lactose and calcium, the point is that the body is able to process calcium better when lactose is present. This would support bone growth. See for example https://www.sciencedirect.com/science/article/abs/pii/S0958694611002160

On immunity, perhaps this claim is associated with milk containing several vitamins, minerals and amino acids, in addition to the antimicrobial qualities and probiotics. Some of these disappear during processing and (natural) fermentation, some increase in quantity.

A benefit in consuming raw milk is also in reducing risk from spoiling the milk during processing. I understand that even these days with our knowledge and extreme sanitation in industry there are batches that go bad. In earlier times it may have been much more hit-and-miss, crucial during times of hardship.

The seasonal variability of milk production seems to have been taken care about already some time ago, this article from 1923 speaks about calving at all seasons: https://www.journalofdairyscience.org/article/S0022-0302(23)94079-8/fulltext.

In harder climates, people used to live indoors together with animals in the winter. This is great support for calving at any time of year.
 
Seasonal calving in European Prehistoric cattle and its impacts on milk availability and cheese-making

https://www.nature.com/articles/s41598-021-87674-1

Seasonal calving prevailed in Europe between the 6th and 4th millennia cal BC. These results suggest that cattle agropastoral systems in Neolithic Europe were strongly constrained by environmental factors, in particular forage resources. The ensuing fluctuations in milk availability would account for cheese-making, transforming a seasonal milk supply into a storable product.



In traditional herding systems, keeping males and females together throughout the year can result in year-round breeding. The main advantage of this practice is continuous milk supply for the household, but it presupposes good nutritional level throughout the seasons to ensure regular fertility.



Studies involving stable isotope analysis in tooth enamel, conducted on sites dated to the early sixth to fourth millennia cal BC across Europe, have revealed either a restricted birth period2,15,16,17,18,19,20,21, or multiple birth seasons5. Multiple-season calving, perhaps even year-round calving, was also observed at more recent sites dated to the Early Bronze Age and Iron Age in the British Isles3,4



The identification of a birth season of three months (68% of births) at most of the sites and the overall similarity in the calving period in 18 sites across time and space throughout Europe suggest seasonal calving. The consistency of these results contrasts with multiple season calving reported at the Funnel Beaker (3950–3500 cal BC) site of Almhov in Sweden5



A comparison of the timing and duration of the birth period in cattle and sheep would indeed allow for discussions on the complementarity of both species in terms of the availability of animal products throughout the year and the organization of pastoral tasks



Although the birthing season cannot be inferred from our results, out-of-season births seem to occur six months apart from the main calving season (Fig. 3). If the main calving peak took place in the spring, out-of-season births occurred in autumn.
….
Ethnographic literature provides ample evidence for the practice of producing very hard dry cheeses in pastoral societies, where milk is a seasonal food70,71,72,73. Sedentary communities also produce cheeses with a long shelf life. At Kizilkaya in Central Anatolia, for example, each family prepares c. 15–20 kg of cheese, mostly made from sheep's milk, or a mixture of sheep's and cows’ milk, for storage and consumption during winter
 
There are conditions when grasses thrive and grains fail, like very rainy harvest times that cause the grain to sprout or not stand up any more. Or hot and dry summers when the grain doesn’t grow. Grasses are much more resilient and I’m guessing haymaking was discovered in the higher latitudes along with domestication.

There is an article focusing on this from last summer, not sure if we’ve discussed that.

Dairying, diseases and the evolution of lactase persistence in Europe

https://www.nature.com/articles/s41586-022-05010-7


“We propose that lactase non-persistent individuals consumed milk when it became available but, under conditions of famine and/or increased pathogen exposure, this was disadvantageous, driving LP selection in prehistoric Europe.”

On lactose and calcium, the point is that the body is able to process calcium better when lactose is present. This would support bone growth. See for example https://www.sciencedirect.com/science/article/abs/pii/S0958694611002160

On immunity, perhaps this claim is associated with milk containing several vitamins, minerals and amino acids, in addition to the antimicrobial qualities and probiotics. Some of these disappear during processing and (natural) fermentation, some increase in quantity.

A benefit in consuming raw milk is also in reducing risk from spoiling the milk during processing. I understand that even these days with our knowledge and extreme sanitation in industry there are batches that go bad. In earlier times it may have been much more hit-and-miss, crucial during times of hardship.

The seasonal variability of milk production seems to have been taken care about already some time ago, this article from 1923 speaks about calving at all seasons: https://www.journalofdairyscience.org/article/S0022-0302(23)94079-8/fulltext.

In harder climates, people used to live indoors together with animals in the winter. This is great support for calving at any time of year.

Thanks for the link to the article about seasonal vs almost year-round calving. Interesting, though, that seasonal calving still goes on, and still went on then in some areas. Doubtless because, as in the case I described, there might not be enough food for the cows over the winter.

I suppose, as you say, the scientists may be envisioning a famine because of crop failures, but a situation where at least the grass was still plentiful enough to produce enough to store for winter fodder for the animals.

Yes, some people kept the animals indoors with them even to modern times, say the early 20th century. In Italy, especially in the colder, more northern regions, the animals would sometimes be in the ground floor and the humans in the second floor of the house, which was accessed by an outdoor staircase. The smell must have been atrocious, and of course there was disease spread from the animals to the humans with such close habitation, but you could keep an eye on your precious animals, and the heat from the animals would rise to the second floor.

On my mother's ancestral family property in the Lunigiana, the house was built along a rise in the ground, and while there was a cantina or storage area under the house, the animals were in a barn downhill but right next door, with also another barn further across the central work area. The air was more salubrious, and it didn't matter as much that the animals didn't provide heat because it gets to freezing at night in the winter for maybe one night every four years. Rarely does it go below forty degrees F. Also, people used to practice vertical transhumance because of our proximity to the mountains. In summer the animals would go to mountain pastures, and in winter there was still grass cover.

This may all help to explain why the sweep for LP was more intense in northern Europe.

Interesting also that lactose makes the calcium in milk more accessible. I can see where that might increase height, but I don't at all think it affects overall health. East Asians don't consume dairy at all, and they seem to do very well in terms of health, if not height. So do Italians, who have much lower levels of LP than, say, Scandinavians, and yet have longevity rates that are very similar. When I was growing up, the older contadini still worked the land, worked our land too, and they were almost indestructible.
 

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