Ten Thousand Years of Patriarchy

Alice Evans has a long write-up of some of her ideas about the origins of patriarchy, Ten Thousand Years of Patriarchy:

Patriarchy has persisted for at least ten millennia. Cereal-cultivation, the plough and irrigation increased agricultural yields, enabling a taxable surplus, state-formation and social stratification across much of Eurasia. Land and herds were inherited by men, who maintained lineage purity by guarding women.

Eurasia then underwent an important divergence. South Asia and the Middle East saw tightening endogamy (caste and cousin marriage), alongside religious authoritarianism. The more visible the woman, the greater the suspicion and moral ambiguity. By preventing rumour, men preserved piety, honour, and inclusion within vital kinship networks. East Asia remained exogamous, while Europe became increasingly nuclear, democratic, and scientific. But as long as women laboured on family farms (lacking both economic independence and their own social organisations), this global variation in kinship, institutions and religion may not have made an enormous difference.

I was one of the people Alice corresponded with, so I knew the general outlines, but this is a massively interesting effort, and work in progress.

WEIRD cultures collapse traditional social technologies

In the comments Matt reminded me of this preprint that came out last week, Human Parental Relatedness through Time – Detecting Runs of Homozygosity in Ancient DNA. When I first skimmed it my thought was on how ingenious the methods for generating runs-of-homozygosity (to measure inbreeding) from lower coverage (i.e., low quality) ancient genomic results were. It was ingenious precisely because it had a “well, why didn’t I think of that!” quality.

But as Matt notes, the results on the data are interesting too! The first author shared the r.o.h. table, so you can look at them yourself. The major thing to note is that the estimates suggest cousin-marriage was far less common in the prehistoric and historic past than it is in some modern societies. In particular, it is far less common than it is today in the Islamic world and in India. That being said, the r.o.h values do decrease with agriculture from hunter-gatherer periods, indicating that large farming societies were more exogamous…before a recent shift in some areas to endogamy. Wouldn’t this pose some issues in regards to the arguments The WEIRDest People in the World?

How to make sense of all this?

There are several dynamics going on. First, these results put paid to the notion promoted by some behavioral ecologists and anthropologists that most marriages in the past were cousin-marriages. This is just not true. Even hunter-gatherers tended to be exogamous. So was there a cultural change that led to the shift in r.o.h with agriculture? (and its increase with pastoralism in their dataset) No. I think one of the issues we have to remember are simple structural parameters that have nothing to do with ideology.

Hunter-gatherers were at a much lower density than farmers. Elevated inbreeding was almost certainly a function of this ecological circumstance, as gene flow across hunter-gatherer populations was less common simply due to the lack of regular interaction. In the data, the authors point out that a lot of their elevated r.o.h. samples are from islands. Islands don’t impose ideology, they impose limits to contact. The rise of pastoralism and mobility on the steppe in some ways recapitulated the lifestyle of hunter-gatherers (note that I do believe less habitual contact probably meant more xenophobia, so the structural parameter probably had an ideological consequence which amplified what we’re seeing here).

So what explains the pattern in the modern world, and why is it some different from the past? The authors, for example, had transects from Pakistan, and in the past people in this region were not nearly as inbred. The dynamic that is important to remember is the confluence between population growth and the development of what Samo Burja calls “social technology”. In a modern world where societies are undergoing demographic transition and in the earlier stages of that process, so subject to massive growth, there will be lots of cousins to marry. In Malthusian societies, where families are just replacing themselves, there will not be as many cousins to marry. In other words, when there is a strong ideology of cousin-marriage, the limitation is going to be the number of cousins.

As many Islamic societies undergo demographic transition, I predict cousin-marriage will decrease as a phenomenon simply due to the reality that smaller families produce smaller kindreds from which one can select a mate.

But the second aspect here is social technology. In David Reich’s group’s work on India, it seems clear that strong endogamy as we see today did not really crystallize until ~1,500 years ago. Just as one can think of WEIRD culture as a social technology, so Islamic marriage and kinship norms, or that of Hindu jatis, are similar. The practices of these societies are not from time immemorial but develop due to the exigencies of history and social evolution. Practices that we see as “conservative,” such as arranged-marriage, are actually innovations.

Massive population growth has resulted in massive kindreds in many societies. These kindreds have well developed social technologies which are optimized to increase the group-level fitness. The combination of these dynamics has supercharged and spread practices such as arranged-marriage and consanguinity which in the past may have been rare, or accessible only to elites.

If Joe Henrich’s thesis in The WEIRDest People in the World is correct, between 500 and 1000 AD as other societies become more kindred based, the West became less so. It’s special-path diverged greatly up to the present because the combination of material and social technology is the recipe for the amplification of differences of trajectory. The West did not divergence from the rest, everyone diverged from the starting point in the past…

Addendum: Jim Wilson is not a co-author on this paper, even though it is about runs-of-homozygosity. But he is cited, of course (though only once!)

A WEIRD society and the extinction of informal alloparenting

Today I saw a Twitter thread where the issue of raising children came up, and how best professionals can manage the challenge when public schools are not available in the same way as they were in the past with distance learning (this is all due to COVID-19). All sorts of “culture war” topics get entangled into this.

For example, many groups of two-income families are entertaining the possibility of private instructors. This raises objections from those who assert that this exacerbates inequalities. It probably does. But what are the options right now for such families? Nothing I can see on the horizon.*

On a recent podcast, I asserted that my politics today begin and end with the question: “But is it good for the nuclear family?” I am not interested in a long philosophical inquiry into this question. Society is perpetuated by people who have children. Humans are a good. They are the ends. Not the means. I do not think reproduction should be incumbent on anyone, but neither do I think it is healthy that children are viewed now by some as a luxury consumption good.

The brittleness of modern child-rearing practices brings to mind something highlighted in Sarah Blaffer Hrdy’s Mothers and Others: in both our historical and evolutionary past “alloparenting”, where someone who is not the mother or father takes care of the child, has been ubiquitous. It is in developed WEIRD societies that alloparenting has faded. And, I believe that alloparenting has diminished the most in college-educated professionals, who often live far from their relatives, and exist in communities where independence and some level of self-containment is expected. Rather than informal and customary alloparents, children are taken care of by professionals.

Alloparenting has been rationalized. Made efficient. Transformed into economic units of exchange. Unfortunately, it seems this sort of alloparenting is more brittle to an exogenous shock.

This is I think related to the arguments in Joe Henrich’s The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous. The collapse of kindreds, the rise of atomized nuclear families, and the organic development of civil society generated the economic bounty and innovation we see around us today.

But reading Henrich’s book I began to worry that WEIRD individualist societies were fragile. And their equilibrium was meta-stable at best. Without growth, the frontier, and economic bounty, I am skeptical that the WEIRD way can maintain itself, as society retrenches back to the traditional social arrangements of kith and kin.

* One option is that one parent stays at home. That’s how we do it. But most people plan on a certain level of income, and some people are single-parents. So it’s not feasible to imagine millions of people shifting their lives so rapidly.

The Dark Age roots of Western modernity

Since Joe Henrich’s The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous isn’t out until September, I will wait to pitch a full review (probably to National Review) until then (well, actually, I’ll pitch later this month and have it ready to go with the book is out). But it’s a rich work which is stimulating food for thought, so I’ll post on it until then on this weblog. The author writes in a relatively academic and objective manner, so it doesn’t have an outrageous title such as “How the Roman Catholic Church invented the modern world in the Dark Ages.” But a lot of it does feel like that.

The key aspect, and most persuasive element, to me, is that the collapse of the Roman system presented an opportunity for the institutional Western Christian Church. Decisions in the early medieval period set in train a set of cultural changes and effects which resulted in the deep structural reasons why the modern world was likely to come out of the West. The author admits that he believes the power of cultural selection and evolution is such that it can overwhelm other factors (he is, after all, a cultural evolutionist!).

Two examples, of different levels of importance and strength. First, the fact that before 1900 cities were incredible demographic sinks implies that there was selection against the type of personality which would wish to live in cities (W.E.I.R.D.). There is a lot of evidence that premodern cities were black holes. They ate up the demographic base of the countryside and always needed more. With the development of independent free cities in the medieval period and their growth in the early modern stage, there was a strong genetic selection effect on the type of personality which might be attracted to cities. Nevertheless, society kept getting more W.E.I.R.D. Not less. A good analogy here I think is Roman Catholicism and France. In the early 19th century demographics (migration from Poland, for example) already worried secular French intellectuals that Roman Catholicism would make a massive come back. France was demographically undergoing transition, and Catholics kept having children.

Ultimately that didn’t happen, because the cultural force was just too strong to swing upstream against.

The second example is looking at selection against EDU (years of educational attainment) in terms of SNPs recently discovered. Henrich presents this result without critique but argues that the cultural context of intellectual work is such that we’re far more productive than we were one hundred years ago. This can be disputed some, but I think a lot of that argument has to do with “low hanging fruit.” Telsa and SpaceX are still doing things.

But there’s another example that came to mind as I was reading The WEIRDest People in the World. Like Jared Rubin in Rulers, Religion, and Riches: Why the West Got Rich and the Middle East Did Not Henrich is positive toward the idea that Protestantism and modernity go hand in hand. Think of it as a bit of neo-Weberianism. I don’t personally accept the psychological explanation without further evidence, though it seems that descriptively the correlation is robust. Rather, I want to highlight a countervailing trend of the Reformation: the increase in rates of cousin marriage and patriarchal authority within the family. One of Henrich’s major arguments, prefigured by other thinkers, is that the institutional power and incentives of the early Roman Catholic Church were arrayed against the coalescence of powerful aristocratic kindreds and descent-groups after the fall of Rome. Additionally, the Church served as an institutional escape valve for many women who wished to delay or avoid marriage, becoming part of religious orders and such. The collapse of the institutional Church in Protestant Europe initially resulted in the rise of cousin marriage among elite lineages, as well as greater control of fathers over the choices of their offspring in terms of partners. Readers of this weblog may know of the Darwin-Wedgewood family.

This is not a pattern exclusive to Protestant Europe. L. L. Cavalli-Sforza reported data from Italy where modern transportation resulted in decreased rates of consanguineous marriage…followed by anti-clerical sentiment produce a resurgence in some areas (as the Church no longer could enforce bans on distant cousins marrying).

Nevertheless, something like the Chinese clan system never reemerged in Europe, despite the structural forces. History is not a long unimpeded march, but the sum total outcome of periodic tensions, tremors, and disruptions. The obliteration of the Western European extended kinship system by the Church between 600 and 1000 A.D. seems to have been so total that it was not possible for shocks like the Reformation to reverse the pattern, despite local patterns.

Culture and the norm of reaction

A new preprint, Cultural Evolution of Genetic Heritability, is useful at least as a literature review for the uninitiated:

Behavioral genetics and cultural evolution have both revolutionized our understanding of human behavior, but largely independently of each other. Here we reconcile these two fields using a dual inheritance approach, which offers a more nuanced understanding of the interaction between genes and culture, and a resolution to several long-standing puzzles. For example, by neglecting how human environments are extensively shaped by cultural dynamics, behavioral genetic approaches systematically inflate heritability estimates and thereby overestimate the genetic basis of human behavior. A WEIRD gene problem obscures this inflation. Considering both genetic and cultural evolutionary forces, heritability scores become less a property of a trait and more a moving target that responds to cultural and social changes. Ignoring cultural evolutionary forces leads to an over-simplified model of gene-to-phenotype causality. When cumulative culture functionally overlaps with genes, genetic effects become masked, or even reversed, and the causal effect of an identified gene is confounded with features of the cultural environment, specific to a particular society at a particular time. This framework helps explain why it is easier to discover genes for deficiencies than genes for abilities. With this framework, we predict the ways in which heritability should differ between societies, between socioeconomic levels within some societies but not others, and over the life course. An integrated cultural evolutionary behavioral genetics cuts through the nature-nurture debate and elucidates controversial topics such as general intelligence.

I’m not sure that the modeling here really solved things too much, though it pushed the ball forward. But in any case, a cultural evolution framework clarifies and makes more precise what was always well understood from a quantitative and behavior genetic approach. Heritability is simply a population-level statistic that is always conditional on various environmental parameters. The heritability of height and intelligence likely are both higher in WEIRD environments because of cultural homogeneity. The homogeneity reduces the environmental factor and increases the impact of genetics on variation.

The authors take pains to distinguish their framework from gene-environmental interactions or gene-environment correlations. These two are widely explored in the behavior genetic literature. Rather, they suggest that cultural evolutionary pressures and characteristics over time modulate the effect size and direction of various SNPs on a trait. They suggest that cultural evolutionary modeling can help more easily explain the Flynn effect.

This preprint makes a lot more sense when you consider that the last author has written about the importance of theory in understanding and exploring scientific domains. I think the big theme of this preprint is basically to remove the environment from the domain of ad hoc noise residuals. In fact, they state this clearly, insofar as cultural variation is not simply ad hoc noise, but often exhibits directionality. In societies with more environmental variance on a trait, obviously the heritability will be lower, and vice versa. These are novel enough insights, though I’m not sure that one can say the problems were solved in their dual-inheritance modeling.

Update: I received the below from a friend who has a long critique of this preprint.

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Peasant cultures abide

Many years ago I read Tim Blanning’s The Pursuit of Glory: The Five Revolutions that Made Modern Europe: 1648-1815. Some portion of it was dedicated was the attempt of scientifically oriented rulers to encourage the cultivation of potatoes amongst their subjects. Today Russia is huge on potatoes, but during the reign of Catherine the Great, this was not the case. Blanning outlines the resistance of the superstitious and backward Russian peasant in particular to the new wisdom of the agronomists. Truth be told, these illiterate peasants really didn’t give reasons for potato aversion. They simply pointed out that planting potatoes was not “how it was done.”

This Russian skepticism was common among European peasant cultures. But there was a major exception: Ireland. The Irish cultivation of the potato allowed for prosperity and population growth. By 1800 one third of the population of the United Kingdom were Irish.

This changed. The potato famine led to mass starvation and emigration.

We all know the reason: the famine. The reality here is that Russian stubbornness may not have been easy to rationalize, but the rejection of “expertise” in this case was socially meritorious.

Why cultures explode and fizzle

David Warsh’s Knowledge and the Wealth of Nations: A Story of Economic Discovery is one of the few books on economic modeling which is written well enough to be a page-turner. Warsh’s narrative deals mostly with endogenous growth theory, which focuses on innovation as being the primary driver of economic growth (as opposed to classical dynamics such as gains through trade and division of labor).

I’ve been thinking about this because people often ask me about why cultures go through various efflorescences at particular periods, or why there is stagnation at other times and places. One-size-fits-all answers are generally not ones I find appealing. What confluence of factors produced 5th-century Athens? The Athens of Aeschylus, Sophocles, and Euripides. The Athens of Thucydides, Hippocrates, of Plato and Socrates. A small city-state on the knowledge of the Eurasian oikoumene.

One of my favorite essays is James F. Crow’s Unequal by Nature: A Geneticist’s Perspective on Human Differences. Written 2002, Crow simply observes that if excellence in a particular field is conditional upon being at the tails of several independent distributions, then very few people will be excellent, and subtle differences in distributions across populations can compound rather rapidly. Reading the essay one likely thinks of mental and physical abilities and endowments of particular individuals, but what if one imagines this as a metaphor for sets of societies?

Our understanding of the details of how societies function and integrate into an “organismic whole” is primitive. But we do know that different societies differ in their endogenous and exogenous parameters. Some societies go through external shocks that differ in kind and frequency (e.g., the relative regularity of the Nile compared to the Euphrates and Tigris). Others experience tumult that is purely internal (the secular cycle of decay due to elite overproduction predicted by Peter Turchin). If cultural efflorescence is due to a range of interlocking factors, searching for magical necessary conditions may not be easy (especially if there are different parameter conditions that are sufficient to produce the same result).

All this was on my mind reading a new preprint, Cultural evolution by capital accumulation. The authors refer to endogenous growth theory, and their model shares a great death with micro and macroeconomic ways of viewing the world. From the abstract:

…cultural knowledge creates wealth that can then be invested into the production of further knowledge, generating a positive feedback loop allowing significant accumulation and acceleration. These results prompt us to change the way we see cultural evolution. Instead of an accumulation of unintended random “mutations,” as in genetics, cultural evolution should rather be seen as an accumulation of assets that gradually improve productivity and allow individuals to learn, master and create an increasingly higher amount of further assets.

The paper outlines a model of individual “growth” where one can invest in disposable capital (getting bigger and healthier) and non-disposable capital (stuff that persists beyond death), as well as social learning and innovation. Certain cultural conditions hold whereby social learning and innovation become much easier due to accumulated cultural capital. An example given is the difference between the Roman and Arabic numeral system. Math proceeded much faster under the latter system than the former. Another is the fact that science is cumulative and contingent, so that modern students take for granted as basic discoveries that which had been exotic and cutting edge in earlier centuries. Like a modular machine, the authors describe a cultural system where interlocking specializations of learning yield gains to overall productivity in a very Adam Smith-like manner.

Cultural knowledge resulting in even more capacity to produce knowledge and skill is important. The authors note that extremely dense and large polities are not usually known for their creativity. Rather, smaller units of culture and organization, such as Athens in the 5th-century BC or Britain in the 19-century, seem to shine brightly for a period, before a new equilibrium is reached (Peter Turchin has observed that innovation and change tend to occur on political and civilization frontiers).

The mathematical formalism in the preprint above is not trivial and needs to be checked. But the stylized empirical predictions of stable equilibrium states of poverty, and then periodic shifts to a state of higher productivity, ring true. But, the treatment is deterministic, when it seems likely that the true paths tend to be impacted by stochastic forces.

Going beyond WEIRD dichotomies-cultural anthropology with a genetical lens

From my 10 questions for Luigi Luca Cavalli-Sforza I asked him about the reaction of anthropologists to Cultural Evolution and Transmission, a book written in the late 1970s with Marcus Feldman:

I entirely agree that the average quality of anthropological research, especially of the cultural type, is kept extremely low by lack of statistical knowledge and of hypothetical deductive methodology. At the moment there is no indication that the majority of cultural anthropologists accept science – the most vocal of them still choose to deny that anthropology is science. They are certainly correct for what regards most of their work.

He judged that Cultural Evolution and Transmission had little influence. But Peter Richerson and Robert Boyd learned the application of population and quantitative genetic modeling to cultural dynamics from Feldman in the 1980s. In their own turn, they trained researchers such as Joe Henrich.

Henrich in his turn helped train scholars such as Michael Muthukrishna. Here’s a preprint that has me really excited, Beyond WEIRD Psychology – Measuring and Mapping Scales of Cultural and Psychological Distance:

We present a new tool that provides a means to measure the psychological and cultural distance between two societies and create a distance scale with any population as the point of comparison. Since psychological data is dominated by samples drawn from the United States or other WEIRD nations, this tool provides a “WEIRD scale” to assist researchers in systematically extending the existing database of psychological phenomena to more diverse and globally representative samples. As the extreme WEIRDness of the literature begins to dissolve, the tool will become more useful for designing, planning, and justifying a wide range of comparative psychological projects. We have made our code available and developed an online application for creating other scales (including the “Sino scale” also presented in this paper). We discuss regional diversity within nations showing the relative homogeneity of the United States. Finally, we use these scales to predict various psychological outcomes.

For the people who know genetics, they have created a cultural analogy of Fst!!!. From the preprint:

Cultural FST (CFST) is calculated in the same manner as Genetic FST, but instead of a genome, we use a large survey of cultural values as a “culturome”, with questions treated as loci and answers treated as alleles.

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Rice culture reduces individualism

The above map comes from a 2014 paper, Large-scale psychological differences within China explained by rice versus wheat agriculture. From the abstract:

Cross-cultural psychologists have mostly contrasted East Asia with the West. However, this study shows that there are major psychological differences within China. We propose that a history of farming rice makes cultures more interdependent, whereas farming wheat makes cultures more independent, and these agricultural legacies continue to affect people in the modern world. We tested 1162 Han Chinese participants in six sites and found that rice-growing southern China is more interdependent and holistic-thinking than the wheat-growing north. To control for confounds like climate, we tested people from neighboring counties along the rice-wheat border and found differences that were just as large. We also find that modernization and pathogen prevalence theories do not fit the data.

Basically, rice has a higher per unit yield than wheat, but requires a lot more coordinated labor input. To grow paddy rice it takes a village.

This insight was not surprising to me, and introduced in David Sloan Wilson’s Darwin’s Cathedral: Evolution, Religion, and the Nature of Society. In this book Wilson argued for a rehabilitation of the tradition of evolutionary functionalism in the social sciences. Basically, viewing human societies as adaptive functional units. One of his examples to illustrate the necessity of examining group-level function was wet-rice paddy agriculture in Bali, which was only feasible through coordination and collective action between interdependent farms.

The 2014 results made total sense to me in light of what little I knew. Southern Chinese are stereotypically more patriarchal and clannish than Northern Chinese. My inference here being that the collectivist nature of rice agriculture meant that paternal clan units of social organization were more important in the South than the North.

I haven’t followed up on this work at all in all these years. Then I saw this on my Twitter feed: Teens in Rice County Are More Interdependent and Think More Holistically Than Nearby Wheat County.

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Learning from cultural anthropology as opposed to unlearning from cultural anthropology

On my other weblog one of the commenters, who I have nicknamed Syme (others call him Bentwig), proudly boasts about his training anthropology. Those who know me personally are aware that for me this is often a red flag for an individual who is willing to furiously declare that up is down if Edward Said stated that this was so in a footnote somewhere, or that black is the palest color if Michel Foucault averred this offhand in an interview. I exaggerate in the generality, though in the case of Syme/Bentwig there is a common tendency to proudly attempt to forestall arguments with comments of the form “Edward Said said….” or “According to Foucault.”

Of course, arguing from the authority of others isn’t always bad…but with far too many people with undergraduate anthropology backgrounds seem to engage in this sort of argument-by-citation and refutation-by-declaration-of-theory. Perhaps a contrast of interest are people educated in philosophy. There’s not much they know in thick detail, but they often exhibit analytic acuity when presented with startling and novel information. In contrast, many people with anthropological training may express befuddlement and then proceed to fury when confronted with facts which are outside of their domain and foreknowledge.

Enough punching down. Alex Mesoudi, a scholar in the field of cultural evolution, is publishing book chapters as preprints. The author of Cultural Evolution: How Darwinian Theory Can Explain Human Culture and Synthesize the Social Sciences, Mesoudi’s first submission, The study of culture and evolution across disciplines, should be read by anyone who is interested in the material on this weblog.

Mesoudi reviews the history of the field, from the rise and fall of human sociobiology in the 1970s to the birth of evolutionary psychology in the 1980s, and the gradual but consistent waxing of lesser-known disciplines such as cognitive anthropology and human behavioral ecology (out of which comes cultural evolution). A consistent binding feature of these disciplines is that they attempt to understand human cultural expression as a function of naturalistic processes, in particular, evolutionary ones. This is in contrast to the shift away from analysis to interpretation and description in much of cultural anthropology across the same time period, with the ultimate secession of much of the field from “science.” If you want to read a good primer on the division between scientific and non-scientific anthropology, I recommend Dan Sperber’s Explaining Culture or the anthropological introduction to D. Jason Slone’s Theological Incorrectness. Scott Atran also tackles the issue in In Gods We Trust. The reason this is necessary is that to understand and take in cognitive anthropology, you often need to unlearn or dampened tics obligate in cultural anthropology.

The flight of much of American cultural anthropology from crisp and powerful analytic frameworks, and toward linguistic obscurantism, to me explains the relative poverty of cognition of those students with only an undergraduate training. Without field-work and graduate courses and reading there’s not even the ability to obtain the deep knowledge required to enable feats of “thick description.”

In any case, the genius of the tradition in which Mesoudi operates under is that it allows for powerful analysis and prediction of cultural patterns and dynamics. Using similar formal frameworks, the idea is to do to culture what population genetics has done to biological evolution: produce a machine to generate predictions and test them with empirical data.

Here’s a taste of how researchers in this field think of “cultural patterns”:

Boyd and Richerson (1985) developed models showing that transmitted culture is favored when environments change moderately quickly, too fast for genes to track, but not so fast that the culturally transmitted behavior is out of date (see also Aoki et al., 2005). Transmitted culture also evolves when individual learning is costly (Boyd and Richerson, 1985). Under such conditions, however, social learning evolves but does not increase the average fitness of the population. This phenomenon became known as “Rogers’ paradox” after Alan Rogers, the first person to clearly point it out (Rogers, 1988). The fact that social learning does not enhance average population fitness is not inherently paradoxical, but does contradict the common claim that humans are so ecologically and demographically successful because of transmitted culture.

Rogers’ paradox occurs because the success of social learning is frequency-dependent. When rare, social learners do well because they forego the costs borne by individual learners. But when common, and environments change, social learners will be copying other social learners’ out-dated information. At equilibrium, social and individual learners have equal fitness, which will be equal to the fitness of a population entirely composed of individual learners (which is fixed, because their learning is not dependent on others). Thus, social learning evolves, but does not enhance fitness in a way that could be described as the ‘secret to our success’.

Two small quibbles with the chapter. First:

Bouckaert et al. (2012) reconstructed the cultural evolutionary history of the Indo-European language family, finding that it originally spread along with farming practices from present-day Turkey around 8,000 years ago.

Bouckaert et al. used valid phylogenetic methods, but it seems quite clear that these models have difficulty predicting the protean and punctuated character of many population expansions, which reshape the distribution and relationship of languages. Since 2012 a substantial amount of ancient DNA work has strongly pointed to the likelihood that the distribution of extant Indo-European languages in Europe is due to an expansion out of the Pontic steppe 5,000 years ago (with later secondary migrations into Southern Europe after 4,000 years ago). Though the Anatolian origin may still be preserved if one argues that the Pontic expansion was a secondary one, clearly most of the diversification of the Indo-European languages occurred in the period between 3000 and 1000 BC, in a 2,000-year radiation. The “Indo-European question” ultimately showed to me the limitations of phylogenetic methods because they are sensitive to particular assumptions within the model (e.g., continuous endogenous demographic expansion).


Note that this is different to Wilson’s (1976) earlier speculations that genetic differences might explain behavioral differences between groups of people. Tooby and Cosmides explicitly disavowed this, instead arguing that people everywhere are genetically far too similar to explain any behavioral variation directly (which concurs with modern genetic data: Feldman, 2014). Genes instead generate a set of universal responses to predictable environmental variation.

Considering the very rapid changes in cultural types across time and between closely related lineages, it seems hard to credit that most behaviorally based cultural variation is due to genetic variation (e.g., walk down a street in Finland and walk down a street in Italy, and see how differently the comportment of the typical passerby is). But, it seems quite possible, probably likely, that there are going to be some behavioral differences due to different distributions in polygenic quantitative traits. The question is more the extent of magnitude. That will depend on the phenotype and between population pair.

Also, there is clearly variation within the cultural evolution community on this issue. I know this from personal communication. Joe Henrich admits the possibility in The Secret of Our Success, without taking a position.

But, with those quibbles out of the way, go and read The study of culture and evolution across disciplines. I think it’s great that Mesoudi is putting out preprints for his book chapters. Makes his research accessible, and this is one field where more publicity would be good (shout out to Paul Smaldino, who apparently inspired Mesoudi on this track).