Cognitive evolution in Western Europe

From medieval to modern times

Philosopher in meditation, Rembrandt (1606-1669)

At the height of the Middle Ages, most Western Europeans were still trapped in irrational ways of thinking — revealed truth, finalism, predestination, animism, and anthropomorphism. The stars, the moon, the sea, and the weather were all seen as conscious entities that could help or harm, depending on their mood. “Good luck” and “bad luck” were similarly viewed as intentional processes. There was no fine line between animate and inanimate, subjective and objective, or cause and effect (Oesterdiekhoff, 2012).

Some individuals did rise above this mindset, but they had few opportunities to meet others like themselves. Even as counsellors to monarchs, they were alone in the world, their full worth neither recognized nor appreciated, and their best ideas confined to unspoken thoughts. Intellectual progress remained slow without a critical mass of people who could understand new ideas, criticize them, improve on them, and put them into practice.

This situation began to change during the Late Middle Ages. A ferment was stirring among scholars, as shown by a renewed interest in ancient writings and the rise of scholasticism — the use of analytical argument to reconcile Christianity with pagan philosophy. “Men of reason” had more opportunities to come together. At first, they met in each other’s homes or at monastic schools; later, as they became more numerous, they gathered in more secular venues, like salons, coffeehouses, and learned societies. Such men would usher in the post-medieval era: a time of accelerating progress not only in the sciences but also in literature, music, and the arts (de Courson et al., 2023).

What caused this great advance to happen? For Gregory Clark, who has studied English demographic history, the cause was the growth of the middle class. As the market economy expanded from late medieval times onward, it created niches for young middle-class men and women, who could now marry earlier and have more children. But their higher rate of natural increase often overshot the number of niches created, forcing some children down the social ladder. Because the lower class was not reproducing itself, due to a higher death rate and lower marriage rate, the entire English population became increasingly of middle-class descent.

This demographic shift was paralleled by a mental and behavioral one: “Thrift, prudence, negotiation, and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent, and leisure loving” (Clark, 2007, p. 166; see also Clark, 2009; Clark, 2023).

Were the mental and behavioral characteristics of the middle class due to good upbringing or good genes? Likely both. Middle-class parents were passing on both a certain morality and a certain genotype, including alleles associated with higher cognitive ability. This is what we see in the data.

A new research tool

Our understanding of recent human evolution has undergone a sea change with the retrieval of DNA from human remains. By examining the alleles of certain genes at different points of history and prehistory, we can observe how human populations have evolved—not only physically but also mentally and behaviorally.

We can infer the evolution of cognitive ability from alleles associated with IQ or educational attainment. Although this polygenic measure is unreliable for any one person, it can be reasonably accurate for a group (Piffer, 2025). In fact, it shows a high correlation with mean population IQ, in the range of 0.82 to 0.98 (Piffer, 2019).

To chart the cognitive evolution of Western Europeans, geneticists Davide Piffer and Emil Kirkegaard compared 467 genomes from two periods: Late Antiquity to the Middle Ages; and the present day. Their comparison showed a large rise in cognitive ability over time — between one third and one half of a standard deviation (Frost, 2024a; Piffer & Kirkegaard, 2024).

The actual rise may have been even larger because the comparison was between medieval and present-day genomes. According to Gregory Clark, cognitive ability was already rising during the Late Middle Ages, at least in England and probably elsewhere in Western Europe. At the other end of the timeline, cognitive evolution seems to have stalled during the Victorian Era and then reversed in the 20th century (Frost, 2022; Kong et al., 2017; Woodley et al., 2013).

To identify the actual timeline, Davide Piffer and Gregory Connor did a second study with 269 genomes from one region of England (Cambridge and surrounding area) between the 11th and 19th centuries (Piffer & Connor, 2025a). This study brings the trend of cognitive evolution into sharper focus: little change at first, followed by a steady rise from the 1300s onward. Particularly impressive is the increase in the “smart fraction”: the top 1% in 1850 was as smart as the top 0.1% in the year 1000.

Piffer and Connor then did a third study with a larger sample of 600 genomes and a broader geographic and temporal scope — Belgium, Denmark, England, Germany, and the Netherlands between the 8th and 19th centuries (Piffer & Connor, 2025b).

They again found the same timeline:

• No clear change until about 1350, followed by a steady rise until 1850. The total increase was a little over three quarters of a standard deviation.

• The inflection point seems to be the Black Death (1346-1353). This major pandemic may have kickstarted cognitive evolution in Western Europe by weakening feudalism and freeing up human capital for the emerging market economy: “labour became scarcer, wages rose, and land and capital became relatively cheaper. In that new environment, individuals who could exploit opportunities in trade, crafts, and skilled work had strong advantages” (Piffer, 2025b).

• On a per capita basis, the highly intelligent became over ten times more numerous in Western Europe between 700 and 1850. In other words, the top 1% in 1850 were smarter than the top 0.1% in 700 (Piffer & Connor, 2025b; Piffer, 2025b).

Cognitive evolution in Western Europe from medieval to modern times. Was it kickstarted by the Black Death? (Piffer, 2025b)

Discussion

These findings shed new light on Western European history, particularly the arbitrary line drawn between the Middle Ages and later times — typically at the year 1500. In reality, the entry into modernity was gradual. If a line must be drawn between pre-modernity and modernity, it should be set at around 1350, when the Black Death ravaged feudal Europe, wiping out between 30 and 60% of the population and facilitating the rise of a new economic system and dominant class.

Its aftermath saw a sustained expansion of the market economy. Young middle-class men and women could marry earlier and have more children, who could also provide their family business with cheap labor. Such families formed a growing proportion of the population. With each passing generation, there were more and more people who could exploit market opportunities through their skills in literacy, numeracy, and planning. The new economic context was favoring their success and, hence, the success of their moral values and genetic traits.

In sum, a changing economy was coevolving with a changing genome, with each pushing the other forward. And the spillover effects on intellectual life went far beyond bookkeeping and merchandising. As mean cognitive ability increased, so did the numbers of the highly intelligent. They were becoming a class of their own.

The last point is crucial. Progress is driven not only by exceptional individuals but also by exceptional communities that can appreciate the worth of new ideas and put them to use. Otherwise, new ideas are left to rot on the vine. For example, the printing press was not really invented by Johannes Gutenberg in 1440 — this was when it became commercially viable. It could have been invented earlier, and traders had already seen movable-type presses in East Asia, but there was no need to mass-produce books, at least not in Europe. Now there was a need.

The big picture

The great cognitive advance after 1350 is part of a bigger picture. If we combine the recent study of genomes from Western Europe with an earlier one of genomes from central Italy, we can tentatively propose the following timeline from the Roman Period onward:

27 BCE – 300 (Imperial Era) - Cognitive ability declined on average, primarily because the elite was failing to reproduce itself (Frost, 2024b; Piffer et al., 2023). Possible causes:

1. Decline of marriage, as described by Augustus in a speech to the equestrian class: “[W]hen the knights were very urgent, during the games, in seeking the repeal of the law regarding the unmarried and the childless, he assembled in one part of the Forum the unmarried men of their number, and in another those who were married, including those who also had children. Then, perceiving that the latter were much fewer in number than the former, he was filled with grief” (Cassius Dio. Roman History, 56).

2. Hypogamy between elite men and women of low status, often slaves or ex-slaves. Elite women thus became less important to elite fertility. If a slave owner had no children by a wife, he could leave his estate to the children he had presumably fathered with slave women or to emancipated boys and girls for whom he had developed affection (Rawson, 1986, 2014, pp. 173-179).

3. Increase in the slave population. Previously, elite offspring could, if need be, find niches further down the social ladder. In this way, the lower class (which had negative natural increase) was continually replenished by the demographic surplus of higher classes. Mean cognitive ability thus rose progressively from generation to generation. During the Imperial Era, however, there was less downward mobility: lower social niches were deemed unfit for higher-class offspring and filled normally by slaves or freedmen. (Harris, 1999; Saller, 1994).

300 – 800? (Late Antiquity) - The decline of mean cognitive ability reversed with the rise of Christianity. Possible causes:

1. Aggressive promotion of monogamy by the Church, which forced elite men to focus on procreation with a lawful wife, usually of similar status, rather than on sex with prostitutes or slave women. Socioeconomic success thus translated into reproductive success, and hence into selection for cognitive ability.

2. Shift from orthopraxy to orthodoxy, i.e., from correct conduct (paganism) to correct belief (Christianity). The Church favored those who were better at learning its rules, teachings, and doctrines.

800? – 1350 (Middle Ages to the Black Death) - Cognitive evolution now entered a period of either stasis or slow increase that cannot be measured with current data. Possible causes:

1. Rise of feudalism, from the 9th century onward. Feudal manors provided security in exchange for personal freedom. With fewer life choices, and less scope for innovation, serfs had fewer cognitive demands to deal with (Schooler, 1976).

2. Rise of monasticism, especially the Cluniac movement (founded in 910). Monks came disproportionately from aristocratic families, who provided endowments and appreciated the education provided by monastic living (Janin & Carlson, 2023, pp. 14, 39). Their vows of chastity kept them from passing on their mental aptitudes.

1350 – 1850 (late medieval and post-medieval periods) - Cognitive evolution accelerated after the Black Death and continued at a fast pace until the Victorian Era. Possible causes:

1. Growth of the middle class, due to the expanding market economy.

2. Gradual demographic replacement of the lower class, through the downward mobility of surplus middle-class individuals and the failure of the lower class to reproduce itself due to a higher death rate and lower marriage rate.

1850 – present (Modern Era) - Mean cognitive ability plateaued and eventually declined (Frost, 2022). Possible causes:

1. Shift from cottage industry to factory capitalism, where a business no longer relied primarily on family members to do the work, and where the workforce could now be expanded or contracted at will through hiring or firing. Because businesses were no longer “ma and pa” shops, the owners, generally men, had no economic incentive to marry early and have children. Reproductive success was thus severed from socioeconomic success

2. Creation of new needs to maintain a middle-class lifestyle, including the maintenance of a wife and family. Children became more costly and offered fewer economic benefits.

3. Decline of religion, especially the relaxation of its restrictions on marriage, divorce and sexual behavior.

The pre-medieval timeline, like the later one already discussed, sheds new light on the historical process. The Imperial Era now seems less impressive. Despite its grandeur, it coincided with an unsustainable running down of human capital, as often happens in empires. This decline then reversed during Late Antiquity, which now seems less tragic. Yes, the Western Empire collapsed, as did much of Roman culture, but this period also brought the rise of Christianity and a reorganization of society on a more sustainable basis.

Future research

Hopefully, we will see more studies of the sort reviewed here, particularly for late medieval and post-medieval times. By charting the cognitive advance by region and by century, we may learn more about the historical processes leading to the Renaissance, the Reformation, the Scientific Revolution, the Enlightenment, and the Industrial Revolution, all of which are arbitrary segments of a single continuum extending across space and time.

Here are a few avenues for future research:

Did mean cognitive ability begin to rise earlier in some regions than in others? While the Black Death clearly assisted the rise of the market economy, and the consequent expansion of the middle class, both trends were already under way in North Sea ports from the 7th century onward and in Italy after the year 1000. Did these regions experience an earlier rise in cognitive ability? In Italy, for instance, scholasticism was already reaching its high point in the 1200s and early 1300s, well before the Black Death.

Were there “hot spots” of unusually strong cognitive evolution? Such hot spots may have arisen wherever cottage industry predominated between the 15th and 19th centuries, particularly in Westphalia, Saxony, the Zurich uplands, Piedmont, Lombardy, Alsace, Flanders, Brittany, Lancashire, Yorkshire, and Ulster. In such areas, semi-rural cottagers enjoyed a population boom due to low mortality and high fertility. On the one hand, they lived away from urban areas, where disease and malnutrition kept population growth in check. On the other, they employed family members in their workshops and had no other means to expand their workforce.

These cottagers produced their wares on contract for urban merchants. They thus operated in an elastic, competitive market, with some doing better than others. Those who did better, had more children — generally by marrying earlier and helping their offspring do likewise (Seccombe, 1992, pp. 205, 217). This translation of economic success into reproductive success must have created strong selection for cognitive ability.

Was the rise in mean cognitive ability part of a broader mental and behavioral shift? Clark (2007, p. 166) believes that the English population underwent a broad shift toward “middle class” qualities of mind and behavior — not only higher cognitive ability but also lower time preference, greater impulse control, and less willingness to settle disputes through violence.

Oesterdiekhoff (2023) has argued for a similar shift across Western Europe, describing it in terms of Jean Piaget’s stages of cognitive development. More and more people could go beyond “preoperational thinking,” which manifests itself in egocentrism, anthropomorphism, finalism, and animism. They could now achieve “operational thinking” — the ability to understand probability, cause and effect, and another person’s perspective.

Should the genomic data be controlled for socioeconomic status? Studies of cognitive evolution may suffer from sampling bias because the physical remains of elite individuals are more likely to survive the passage of time. Elite DNA would thus be overrepresented in older samples, and cognitive ability would seem to decrease over time. Of course, we generally see the opposite: an increase in cognitive ability over time. The actual increase may therefore be even greater than current findings suggest.

In any case, we should certainly attempt to control for the SES of ancient DNA, which can be determined from parish records or inferred through isotope analysis of bones and teeth. High SES is associated with an ample, high-meat diet, and low SES with coarse grains and malnutrition.

References

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