In his book A Farewell to Alms, Gregory Clark argued that the demographic growth of the middle class caused the English gene pool to change for mental and behavioral traits, not only cognitive ability but also time preference and predisposition to personal violence. From the 12th century onward, the English population became, on average, more middle class in its values and behavior. "Thrift, prudence, negotiation, and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent, and leisure loving" (p. 166).

Georg W. Oesterdiekhoff has argued that a similar evolutionary change occurred throughout Western Europe during late medieval and early modern times.

Do we now have enough ancient DNA from Western European sources to test this argument? I know we can track evolution in cognitive ability by examining alleles associated with educational attainment. But what about time preference and violent male behavior?

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Is there a way to estimate the average genotypic g of a population from a (probably) unrepresentative sample of ancient genomes. or at least how can you better approximate the true population parameter?

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TE raised the question “Do you agree with Galton’s claim that the Ancient Greeks had particularly high average IQs (I believe he estimated it to be ~130).”

Francis Galton died in 1911, when the concept of IQ did not yet exist. Galton could not have known anything about Piaget’s developmental psychology and he had never heard of the Flynn effect.

When Galton suggested that the greatest concentration of extraordinary thinkers was to be found in ancient Greece, he was probably right – if one considers phenotypic intelligence and relates the comparison to contemporaries, that is, if one considers the cross-section.

In the longitudinal view, Galton was completely off the mark.

According to the Flynn effect, IQ in the most highly developed countries in 1900 was about 70. At the time of the ancient Greeks, it was miles below that.

Even the greatest thinkers of that time were on the cognitive level of children of modern societies.

Aristotle called himself the inventor of syllogism. That means Plato, Socrates and all the other predecessors and the contemporaries of Aristotle did not even know this simple pattern of thinking. Aristotle may have taken the very first steps toward formal-operative thinking, but as Piaget and Garcia (1989) have shown in great detail, the rest of his thinking is at the concrete-operational stage. For example, Aristotelian physics is of an incredible “primitiveness” that corresponds in all respects to the thinking of children.

The Hellenists advanced far beyond Aristotle in terms of mathematics and practical experimentation, but much of their thinking was also preformal.


These facts make it clear that PGS research without explicit consideration of phenotypic intelligence can lead to entirely misleading conclusions.

Without consideration of Piagetian stages of development, PGS studies of ancient humans remain incomplete and may lead readers to absurd conclusions. By far the best source on this subject is the seminal work of Georg W. Oesterdiekhoff. I am always amazed that, with very few exceptions, psychometric intelligence researchers do not want to take note of this tremendous treasure of knowledge. Numerous articles by Oesterdiekhoff can be downloaded free of charge at


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I'm curious about the prevalence of mental illness amongst the different ethnic groups over time. Has this been studied? There are GWAS studies done on schizophrenia, bipolar disorder, Alzheimer's, etc. But how does this compare over time?

Do people in ancient Rome for example have a higher rate of mental illness than today? Steven Pinker wrote a book about the decline of violence over time. I would guess that mental illness also decreased. But are there empirical data to support this?

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How does Cold Winters Theory explain the fact that the first advanced white civilizations of antiquity all arose in temperate Mediterranean climates?

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at what point did humans peak cognitively? are we at our peak now? I know there is some speculation that the Victorians were smarter.. etc. Would love to hear your thoughts.

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I have already made several posts, so it may become annoying. Nevertheless, I want to bring the matter to the point.

The Piffer-Dutton-Kirkegaard article is excellent, but it is incomplete because it certainly misleads many readers.

A key finding is that “During the Republican period however, polygenic scores were higher than they are now, nearly one full standard deviation higher.”

I have no doubt that this statement is correct relative to the PGS of the present sample. But how will the average reader interpret this statement? Probably he will conclude that Romans in the Republican period were much more intelligent than Italians today. Possibly he will calculate that the IQ was almost 115. Exactly this would be complete nonsense, because IQ does not refer to genotypic intelligence, but to phenotypic intelligence.

As Oesterdiekhoff and Breuer (2021) prove in great detail, the Romans were at the concrete-operational level, that is, at the cognitive level of modern children up to age 12. I quote at length from the authors' conclusion:

„The analysis of the branches presented, of animism, magic, religion, violence and morals, is sufficient to evidence that the differences between ancient and modern humans cover the whole range of world understanding and psyche, that is, are not restricted to certain branches or areas. The ancient human being stood altogether on lower psychological stages than modern humans do. Modern humans evolved from preoperational psychological stages to formal operational stages stepwise from generation to generation throughout the last 300 years or so. The ancient Roman citizen instead shared many traits with people called in former times savages or primitives, that is, with nature peoples or stone age peoples. Of course, he was a little bit higher developed although not enough to surmount the psyche of the child. According to (Friedell, 2012), the ancient Roman attained the stage of the 15th or 16th century European. Therefore, the judgment of Dinzelbacher is wrong who equalized the intellectual level of the ancient Roman to that of the present-day modern human being“ (p. 62).

The Romans may have had a more favorable genetic basis, but they could not unfold their potentials. Their phenotypic intelligence was much lower than ours. From our point of view, the ancient thinking appears semi-primitive.

It would be imperative to emphasize this fact, because it is not known to the vast majority of readers, including the vast majority of scientists.

And it would be imperative to discuss the consequences this has for research. One central consequence is:

Without reference to cultural environment, PGS are virtually worthless for predicting phenotypic intelligence.

Where the cultural preconditions are not fulfilled, people cannot develop their potential. Phenotypic intelligence is the result of genes and environment.


Oesterdiekhoff and Breuer (2021). Ancient Roman Civilization and Modern, Industrial Society a Contribution to the Sociological Theory of Long-Term Social Change.


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In yesterday’s post, I emphasized that one must strictly distinguish between genotypic and phenotypic intelligence. In an addendum, I quoted from Oesterdiekhoff and Breuer (2021):

"the ancient Roman attained the stage of the 15th or 16th century European".

The Flynn effect shows that the average IQ in the most advanced European countries in 1900 was about 70. People then were much more intelligent than in the 15th or 16th century. Accordingly, we must put the phenotypic IQ of the Romans well below 70.

If PGS studies were to report that the genotypic intelligence of the Romans was comparable to ours without at the same time pointing out the huge difference in phenotypic intelligence, readers would get a totally wrong impression.

Oesterdiekhoff and Breuer (2021). Ancient Roman Civilization and Modern, Industrial Society a Contribution to the Sociological Theory of Long-Term Social Change.


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It's sometimes said that average national IQ is not that significant because some "smart fraction" of society does everything important. Therefore, it's only important that a "smart fraction" class be sufficiently smart to run the whole system.

I think it would be interesting to explore how the **distribution** of IQ (or other behavioral traits), influences the health and fate of a civilization. Obviously, the distribution effects are mediated by the type of economy and political structure that the society has (with effects flowing in both directions based on distribution of IQ within the population).

Anyway, the question would be: What is the importance (or non-importance) of IQ *distribution* within a society? And how valid is so-called "smart fraction" theory?

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I'd be very interested in learning more about what we know about the evolution of Ashkenazi intelligence over the last hundreds of years. What is the evidence like, how sure are we etc. I’ve heard that we have hundreds of medieval Jewish genomes.

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What's the discernible rate of evolution/change when it comes to the behavioral/cognitive aspects? That will go toward answering how far in the past it makes sense to compare the homo sapiens of today to the homo sapiens of antiquity and have it be an apples to apples comparison, mostly as part of the evolutionary psychology sense-making toolset.

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One must strictly distinguish between genotypic and phenotypic intelligence. The Romans stood entirely on the concrete-operational stage. Only a vanishingly small part was capable of formal-operative thinking, and these only in a narrowly defined domain.

Against this background, what do PGSs tell us?

If an individual has a very high PGS, we know that it had a very high genotypic potential. On the other hand, we also know that it could not fully unfold this potential because the phenotypic level of Roman society was very much lower than ours. Without Piaget's developmental stages and without the seminal work of Georg W. Oesterdiekhoff, PGS research runs the risk of producing meaningless statements.

To avoid misunderstandings: I find PGS research exciting, but I have the impression that some researchers are not aware of the problem.

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Is there any genetic evidence for genetic pacification?

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Is large scale ancient genome sampling possible (a common remark made against your and Emil’s study is that the sample size was very low)? Do you agree with Galton’s claim that the Ancient Greeks had particularly high average IQs (I believe he estimated it to be ~130). How does the cold winters theory explain the relatively low American Indian IQ?

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I heard that hippos were the coolest creatures ever, especially the fashy blue ones? Is there any polygenic evidence of this?

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Is there a large batch of ancient genome samples coming soon? do you have an estimation on how many skeletons from the Roman era are available for DNA extraction?

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