Over at my Substack Iberia: Ancient Europe’s Edge of the Earth (part 1) – Unpacking prehistoric Spanish and Portuguese genetics elicited a comment from Walter Bodmer questioning the representative of ancient burials (i.e., were they just elites?).
My response:
– I bet forager societies were in HWE. That is, there’s no major stratification due to class since class differences are minimal/attenuated.
– A single genome has been pretty predictive of future and past diversity for a given population (e.g., WHG).
– There are populations, like India’s, that are highly stratified by class for many centuries (thousands of years?). But this is the exception, not the rule.
Sediment DNA can be compared to burial DNA. Lower quality coverage will have to be taken into account. But I wouldn’t expect much notable deviations from the main cluster of its time and place.
There can still be stratification but likely not perinnially on well defined class basis even close to the extent of what is found in castes. Quantitative comparison between the two can be made once there is, for example, enough sedimentary whg/villabruna cluster DNA to be compared to whg DNA from skeletal remains and then this variation can be compared to modern castes.
This is one of those things where IBD and RoH methods will help a lot.
If we can work out that person X was in a society of only 20,000 individuals, then its less likely that he/she was an elite, because its hard for the social structure to be there. Or on the other hand, if they’re in a larger society but lack any long range IBD to elite individuals elsewhere, then its also unlikely.
But anyway, there is the question of: “Why does this matter?”. If an individual is an elite person, but living in a society of 100,000 and there’s no real population barriers genetically , why are we interested, from a population genetic point of view?
This does particularly seem more the issue in the Iron Age and later, when social hierarchy and very salient burials does actually matter moire. And from a point of view of trait genetics. If we sample a bunch of Sarmatian warriors with some special warrior type burial, and someone does a GWAS for athletic ability, and we find that they are enriched for that trait, it could be problem to start inferring a population genetic difference on that basis (and not just, these are some people who had no population genetic adaptation but were just people from their society with unusual trait genetics who were buried a certain way).
That is Sir Walter Bodmer to you. It is a compliment to Razib and the quality of his writing that such an eminence grise has read the piece and commented on it.
Any of you who do not have a paid subscription to Razib’s substack shouls sign up, ASAP.
The big elaborate burials might just be elites, but even your average free person in those societies is going to have some type of ritualized burial if that’s the norm in their societies. I can’t recall any societies where it’s just wildly different in type such that you wouldn’t find any remains.
Referencing what Brett said: Of the currently existing remains have researchers made a catalogue of non-elaborate burials? This can be a third category.
Took a second, but just for those who did a double take as I did, HWE is referring to Hardy-Weinberg Equilibrium: “Allele frequencies (or percentages, if you prefer) in a population will remain in Hardy-Weinberg Equilibrium (HWE) from generation to generation if the following assumptions are met:
1. Natural selection is not occurring
2. Migration (Gene Flow) is not occurring
3. Mutation is not occurring
4. Genetic Drift is not occurring (drift is less likely in populations of large size)
5. Mating occurs at random”
Also, WHG refers to the “Western Hunter-Gatherer” ancestry that was predominant in Western Europe prior to encountering the first farmers of the European Neolithic era which started in the post-Last Glacial Maximum Mesolithic era ca 14,000 BCE, with WHG and EEF (early European Farmer) peoples (mostly from Western Anatolia now home to Western Turkey) starting to mix ca. 6,000-4,000 BCE, which a peak just before the arrival of people with ancestry from the Pontic-Caspian steppe began to arrive as early Neolithic farming was collapsing and people were reverting to hunting and gathering and absorbing ancestry from relict hunter-gatherer populations. Incidentally, WHG were predominantly Y-DNA haplogroup I and mtDNA haplogroup U (you could get more specific if you wished in both cases), although, in historical genetics, WHG is primarily used to refer to autosomal genetic profiles as a whole.
FWIW, I share Walter Bodmer’s concern about whether ancient burials were presentative, or if they were they just elites, at least in time periods when we know that there was a major demic shift in a region’s population genetics and some degree of stratification, as there probably was at the time of first contact with steppe people in Europe, and as there likewise probably was at the time of first contact between European hunter-gatherers and the first farmers. And, also, possibly following other mass invasions in the historic era.
Anthropologists usually judge social hierarchies by the accumulation of property by the elite, and the deposition of valuables in graves. But hunter-gatherers cannot accumulation much material wealth because they must move from time to time. That does not mean there are no hierarchies. There are, but they are based upon personal attributes like hunting or fighting ability.
@bob sykes
There are some hunter gatherer graves with content that looked like it would take a lot of time to make, thousands of hours even. There are also new discoveries which indicate that hunter gatherers may have built large temporarily occupied settlements for at least a portion of the year. Though it is true that the amount accumulated will not be as much as the neolithic onward. And pre-neolithic accumulations would be, as you said, more directly based on personal attributes.
@ohwilleke: “FWIW, I share Walter Bodmer’s concern about whether ancient burials were presentative, or if they were they just elites, at least in time periods when we know that there was a major demic shift in a region’s population genetics and some degree of stratification, as there probably was at the time of first contact with steppe people in Europe, and as there likewise probably was at the time of first contact between European hunter-gatherers and the first farmers”
But what would be the actual impact of that? Lower/higher estimates of initial admixture rates? Or would it mostly be ‘We might underrate how much initial y-dna diversity continued, and then got wiped out by later ‘internal’ expansions of high prestige lineages’ or something like this?
(Generally in this context I think it’s highly plausible that the Yamnaya represent a separated social group, because they’re tightly related over distance and their kurgans are pretty high investment/special burial places. But the early Corded Ware burials in generally less ostentatious graves seem more likely to be normal/typical people. Or at least there’s no evidence yet that I know of that they aren’t.)
@Matt
It would overestimate the speed of demic turnover, e.g., upon the arrival of steppe people in one instance and upon the arrival of the first farmers in another, and would miss the existence of potentially large reservoirs of relict or substrate populations that are absent from the ancient DNA record.
Another place this crops up is in a recent study of population genetic population structure in Europe in the historic era, which has homogenized much more slowly than crude estimates of migration rates would lead one to expect.
One concrete example is Bronze Age steppe family v. non-steppe family (not ancestry) based stratification, I’ll find the cite later if I can, involved someplace in Western Europe at the steppe v. non-steppe transition (presumably a Bell Beaker derived population), where they found that infant and child mortality was might higher in non-steppe household (including among non-steppe ancestry children of non-steppe wives in steppe male lead households) than outside steppe families, which the researchers hypothesized derived from better access to resources (especially food, but also possibly quality shelter and clothing) in ruling class steppe householder families. The gap was a big one (IIRC, a factor of two difference in survival rates for children, something that also reduces estimates of how polygamous steppe elites were by providing another explanation for their dominance).
Not exactly on point, but even though pre-migration, lactose persistence was very rare in steppe peoples and Neolithic Europeans, and the selective fitness effects at a level almost unprecedented in human evolution largely initially took place in the post-steppe migration area in Northwesternish Europe, I think I recall seeing studies from ancient DNA showing that the derived LP gene was much more elevated in people with lots of steppe ancestry in that transitional period than in people with low LP levels. This again is evidence of the kind of endogamy practices and class structure in the society that would make bias in ancient DNA samples relevant. The mechanism by which this disparity arose (as well as the precise mechanism that made LP such a selective fitness enhancing gene), however, while it can be speculated about, isn’t entirely clear.
@ohwilleke, OK, fair. I’d like to see that actual study on mortality rate differentials by steppe ancestry/y-dna(either? both? neither? geography from isotopes?) as I can’t remember anything much from the literature on that one.
The only thing I can remember on social inequality with adna was https://www.mpg.de/13979712/1009-wisy-052382-social-inequality-in-bronze-age-households , on the Lech Valley, where they were all basically homogenous on the y structure (at the level of primary haplogroups) and in terms of the steppe ancestry proportion. (There’s some other stuff here – https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241278 – but again that doesn’t seem like quite the same thing as what you’re talking about.)
I guess I also think there would need to be some good evidence that treatment of dead children was equal between the two groups, to get to the amount of observed dead being representative of different treatment, and sample size to get away from chance. That’s doable, in theory, though.