I was invited to speak at the Royal Navy workshop, hosted by the Royal United Services Institute, UK’s leading defense and security think tank.
I discussed the evolution of innovation through collective intelligence, drawing examples from history and archaeology. I also highlighted how modern societies can benefit from past civilizations’ collective intelligence to promote progress and innovation. The papers most relevant to this talk are:
Schimmelpfennig, R., Razek, L., Schnell, E., & Muthukrishna, M. (2021). Paradox of Diversity in the Collective Brain. Philosophical Transactions of the Royal Society B: Biological Sciences. [Download] [Summary Post] [Publisher] [Twitter]
Muthukrishna, M., Bell, A. V., Henrich, J., Curtin, C., Gedranovich, A., McInerney, J. & Thue, B. (2020). Beyond Western, Educated, Industrial, Rich, and Democratic (WEIRD) Psychology: Measuring and Mapping Scales of Cultural and Psychological Distance. Psychological Science, 31(6), 678-701. [Download] [Supplementary] [Code] [Summary Post] [Publisher] [Twitter]
It was an insightful exploration of the role of collective intelligence in human innovation in a defense context. My thanks to RUSI for inviting me and organizing the event.
Robin Schimmelpfenning and I discussed our co-authored paper on the paradox of diversity in the collective brain. We discuss how the rate of innovation depends on sociality, information fidelity, and cultural trait diversity. While cultural trait diversity offers the largest potential for empowering innovation, it also brings with it potential coordination and cooperation challenges. Diversity, in other words, is both a source of innovation and divisive; a double-edge sword. We then propose using cultural evolvability as a framework for resolving this paradox.
Our presentation was followed by a discussion session and subsequently a panel discussion chaired by Dominic Abrams.
Here’s the take home: diversity empowers innovation through recombination but also by definition divides us. We call this the paradox of diversity. A principled way to resolve this tension is by considering cultural evolvability.
We discuss implications for entrepreneurship, polarization & a nuanced take on diversity. This framework can also guide researchers and practitioners in how to reap the benefits of diversity by reducing costs.
Let’s start with innovation: A folk understanding of innovation is that it’s driven by a talented few – the giants upon whose shoulders we stand. But that view is inconsistent with theoretical and empirical work in cultural evolution.
Instead, innovations emerge as ideas flow through our social networks, requiring a specific innovator no more than your thoughts require a specific neuron. See: Innovation in the Collective Brain
People are often unaware of how little they actually deeply understand about the world – what’s referred to as the “knowledge illusion” or “illusion of explanatory depth”. The Knowledge Illusion is a good pop book on the topic.
The world is not only complicated, but more complicated than our psychology allows us to believe. Innovations emerge through incremental improvements through partial causal models and large leaps through serendipity & recombination.
Three key levers that affect innovation are sociality (size & interconnectedness of a population), transmission fidelity (how well you can transmit information between people), & cultural trait diversity. Diversity has the most potential benefit and the largest challenges.
Let me say a bit about each. 1. Sociality: in general +ve relationship, because large pops had to solve the coordination problem to become large. Interconnectivity has an optimal point. Small work groups can be easily overconnected; large pops should be more connected.
2. Transmission fidelity: under selection as cultural complexity increases. Hunter-gatherers not much explicit instruction.Industrial revolution eventually led to schools to download a minimum common cultural package – reading, writing, arithmetic, algorithms for thinking.
Today we have the printing press, radio, TV, Internet, social media, and Zoom. But there’s still too much to learn. Unless you get a PhD, 21C students don’t learn mathematics developed after 1900; scientific training is longer, & major contributions are made at an older age.
We spend longer learning, delaying kids. Theres limit to pop size & transmission; how long you can delay being productive. Another path is to divide up info & labor-specialize. Get smart at 1 thing & stupid at everything else: cultural trait diversity
Different kinds of diversity & different ways to measure it. Our focus is on cultural trait diversity-beliefs, behaviors, assumptions, values, technologies, & other transmissible traits. e.g. languages, processing techniques, technical skills, family structure & occupation.
In the public discourse, diversity often refers to ancestry or physical characteristics-skin color, ethnic origin, religion, sex, gender, sexual orientation, or ability. These may correlate with cultural trait diversity, but correlation may weaken over generations.
For example, Americans with different ancestries may possess similar WEIRD psychology (part of why I have an issue with the WEIRD=White take, though that’s a separate issue). I’ll use diversity from herein, but that’s what we mean.
Diversity can be distributed in different ways: Diversity between pops culturally evolves as pops adapt to local differences, influencing future generations through historical path dependence created by past conditions or founder populations. See also: Psychology as a Historical Science
Diversity within populations evolves as information and labor are divided as discussed above.
Within-population diversity includes disciplinary differences, such as the sciences and humanities, industry specialisations, guilds, and firms. Diversity can be structured as ‘cultural clusters’ by ethnicity, class, wealth, occupation, politics, religion, or incidental geographic layout. Cultural clusters may intersect, such as in ethnic occupation specialization-lots of examples. See also: Beyond WEIRD Psychology: Measuring and Mapping Scales of Cultural and Psychological Distance
Diversity may also exist within certain individuals—multicultural individuals, ‘third culture kids’ (like Barack Obama), interdisciplinary researchers, and so on.
Diversity is therefore both the product of cultural evolution and fuel for the engine of further innovation
But without common understanding & common goals, the flow of ideas in social networks is stymied, preventing recombination, and reducing innovation. Consider communication without a common language or collaborations between scientists & humanities, or different scientists.
We formalize this paradox of diversity trade off in the paper and will be exploring solutions in future work. Check out the paper for details. We argue cultural evolvability is the right way to think about this.
Evolvability refers to not how well adapted a population is to current circumstances, but its ability to evolve to future circumstances. Variation or diversity, and the forces that create and stabilise that diversity are key factors that create evolvability.
Cultural evolvability is a balance between diversity and selection, exploring and exploiting, sampling and specialising, convergent and divergent thinking, stability and change, efficiency and flexibility.
Lots of related work on diversity and selection, explore-exploit or sampling-specialising trade-off in development, search for global solutions & avoidance of saddle points within machine learning.
As an aside, ML insights: in a sufficiently high dimensional space there are effectively no local optima, only saddle points with some dimension that allows escape. Biological & cultural systems have large dimensionality, there are no true evolutionary stable equilibria.
Next, we review the diversity literature through the lens of cultural evolvability. First we lay out 9 challenges to interpreting the literature. It’s a literature that would be benefit from theory. See also: A Problem in Theory
Diversity overlaps with challenging aspects of psychology, norms & institutions: racism, prejudice, xenophobia, sexism, discrimination, power differences, social and economic inequalities.
Love to write about at some point, here we focus on coordination challenges, which influence and are influenced by these problematic features of the world. Our goal is to review the overall patterns in the literature and make sense of these in light of cultural evolvability.
Here’s some of the mixed lit: Within countries, diversity is often approximated by birthplace diversity, professional diversity, ethnic diversity or linguistic diversity. Research looking at the relationship between diversity and economic growth suggests: positive effect of birthplace diversity, but -ve effect of ethnic and linguistic diversity. Research asking questions about immigrants in general often ignore the heterogeneity – cultural distance and education (effectively the cultural traits in your head) matter. Even more mixed in firms. Overall, educational diversity and deep level diversity seem to be positive for innovation within a firm. Mixed effects within teams – we think the paradox of diversity can disentangle.
We derive some insights:
1. Cultural evolvability means tolerance for diversity. Currently less adaptive traits may be more adaptive when the environment changes. Different environments lead to different evolvability strategies. In materially insecure societies, not following a successful “Tiger Mom” strategy—working hard to secure scarce educational opportunities and subsequent employment opportunities—has a much larger cost. But this leads to incremental over radical innovation.
2. Cultural evolvability means under-optimization & inequality. Cultural evolvability necessarily means inequality in outcomes, because not all will have the optimal strategy for the current environment.
Firms face a tradeoff: strategies that favour efficiency & strategies that favour flexibility. Consistent, strong cultures perform well in stable markets, but poorly during times of change. Under-optimizing and allowing for flexibility increases a firm’s evolvability.
Not all firms can bear the cost of under-optimising in the short term-high risk, high value approaches better suited to larger firms or larger countries. Read about Satya Nadella and Microsoft:
Compromize strategies: skunkworks, ecosystems of different firms trying different strategies (e.g. Silicon Valley), or countries composed of different states or regions trying different approaches (e.g. what Justice Brandeis described as “laboratories of democracy”).
In shared multi-agent reinforcement learning, diversity increases performance through exploration and individualized behaviors. Evolvability means many approaches will be suboptimal or even fail, but the successful approaches can be spread and benefit the group as a whole.
Indeed one of the benefits of access to multiple cultures in pluralistic, multicultural societies is the ability to create new approaches by learning, borrowing, copying from each other and other cultures. We should do more of that.
3. Cultural evolvability helps explain levels of entrepreneurship. Cultural evolvability requires doing something different. Most new businesses fail & the willingness to take a risk depends on personal and population-level costs and benefits.
A. personal cost of deviation: many deviations will result in lower payoffs than following the majority trait. If it were obvious how to do better, most of the population would already use the better strategy. Tolerating diversity in traits, thus, means tolerating failure.
Reducing cost of failure increases entrepreneurship: bankruptcy laws, social safety nets, rich parents – a child with parents in the top 1% income distribution is 10 times more likely to be an inventor than a child born below the median, controlling for measures of ability.
B. population-level benefit of deviation. In a large economy with a large customer base comes large rewards for large innovations – the few winners can win bigger. Amazon can make more money in the United States than in Australia. Here’s a great video of Bezos describing his vision back in 1997:
C. Who pays the cost and who benefits from the innovation at a population-level, a function of the scale of cooperation. Even if at an individual-level the benefits of entrepreneurship don’t outweigh costs, they may do so at a population-level.
Silicon Valley offers an example. For every Apple & Amazon, there are 1000s of start-ups that have failed – most start-ups fail & the overwhelming majority never receive funding (114) – ‘unicorns’ are called unicorns for a reason. But the few successes pay for the failures.
4. Cultural evolvability prevents polarization & cultural speciation. Harshly punishing minor deviations increases extremism. If you’re harshly punished anyway, may as well take the extreme position. If there weretolerance for diverse view points, I’d moderate my position.
Model and results also inform debates on freedom of speech, predicting large sanctions for small deviations may encourage a divided society. By corrolary tolerating multicultural diversity of opinions and cultural traits may prevent polarization.
Cultural clustering complicates everything, but I’ll let you read about that in the paper. It gets into colonialism, resource competition, and intergroup violence. 50/ To conclude, diversity has been central to the success of all life. Until around 1.2 billion years ago the source of that diversity was mutation – genetic innovation through serendipity and incremental improvement alone. Single cells reproducing by simple replication.
Sex unlocked the recombinatorial power of diversity, increasing evolvability and the speed of evolution. So too with culture, but there are many barriers to cultural traits meeting and recombining.
We live in an increasingly connected & multicultural world. Migration is a constant feature of the human story, but since the Age of Mass Migration, more people from more culturally distant societies live side by side. Their countries of origin must coordinate as never before.
So much human potential is lost through unequal access to information and adaptive cultural traits. The goal of any society or org should be to reap the benefits of diversity and minimize the costs, thereby maximizing human potential. We discuss several strategies.
Humans are a deeply cooperative species. Our greatest achievements and our worst atrocities are both cooperative acts. In a more diverse world, the challenge is greater, so too are the potential gains.
I was a keynote speaker at the Cooperative AI workshop at the 2021 Conference on Neural Information Processing Systems (NeurIPS). I spoke about “Cultural Evolution and Human Cooperation” and its relevance for understanding problems in cooperative AI. Some of the topics covered included, an introduction to dual inheritance theory and cultural evolution, how and why humans cooperate, and why human cooperation varies in scale, intensity, and domain across societies.
🚨New paper (& #RStats pckg) in Psych Methods: “Parsimony in Model Selection: Tools for Assessing Fit Propensity” w/ Carl Falk
Say you have 2 theories rep in 2 stats models. Which theory/model is correct? The one that best fits the data right?
Ok, but what about parsimony?
Occams razor: given 2 equally fitting models, all else being equal pick the simpler / more parsimonious, model. But how do you quantify parsimony?
Some researchers equate parsimony with degrees of freedom, but as we show you can have fewer parameters, but less parsimony.
Another way to think about it is what Kris Preacher called “fit propensity”. Some models may fit the given data better not because they represent a more correct theory, but because they would fit any data better. Even nonsensical data. It’s the opposite of parsimony.
Incidentally, the context for this research is the theory crisis and the importance of formalizing theory, even if in a statistical model. More here:
New paper: we argue that the replication crisis is rooted in more than methodological malpractice and statistical shenanigans. It’s also a result of a lack of a cumulative theoretical framework: & (nature.com/articles/s4156…)(muth.io/theory-nhb)
Back to fit propensity.
Fit propensity is often ignored in model selection. Perhaps because the answer to “how do we assess fit propensity?” has been “not easily”. In this paper, we fix that.
We offer a toolkit and 5 step process for researchers to assess parsimony of SEMs using an R package (ockhamSEM).
Basic idea: generate random data (or constrained random data, e.g. only positive) as covariances and see which model fits better in this universe of nonsense.
So in the opening model, using standard model selection approach, you might conclude that 2A is a better model than 1A. 2A has a lower AIC so it’s the best theory for generating the data, etc. But you’d have ignored that 2A lacks parsimony.
2A fits a wider range of data better – even nonsense.
Between these models, you might think the factor model is a better fit than the simplex model, but it lacks parsimony – much more so if the data are all positive covariances!
To show some of the complexities of considering parsimony, we investigate the factor structure of the Rosenberg Self-Esteem Scale.
Spoiler: fit indices interact with fit propensity.
The fifth Future of Government Disruptive Debate hosted by the World Bank tackles the issue of citizens’ trust in government. Together with a diverse group of high-profile practitioners, renowned experts, and thought leaders, I discuss how the natural state of affairs is corruption and the challenges government face in getting citizens to trust higher levels of cooperation.
My opening remarks can be found from 7:12 to 14:07 in the recording above. A rough summary of my talk can be found on my substack: https://muthukrishnalab.substack.com/p/trust-governance-and-cultural-evolution
The fifth Future of Government Disruptive Debate will tackle the issue of citizens’ trust in government. The Disruptive Debate series aims is to bring together a diverse group of high-profile practitioners, renowned experts and thought leaders to generate new knowledge and perspectives.
The issue of trust has been a frequent theme arising during the Disruptive Debate series. The panel addressed questions such as: Why is trust important for poverty reduction and shared prosperity? What is the relationship between inequality and trust? What can governments do to increase, or re-build, trust? How can citizens influence and hold governments to account? What has been the role of information, data and social media, particularly during COVID-19?
Some quick background: Religions bind people into communities with moral norms about what is right, good, & true. Ever notice that major world religions seem to have some broad stroke similarities like big families and being nice to neighbors? Why is that?
One hypothesis is that having those helped those religions grow in the competition with other religions. Not all religions in history share these features. The Shakers, for example, an offshoot of the Quakers, practiced celibacy not just for a priestly class, but for all.
The Shakers are no longer with us.
But religions also have plenty of differences, not only in explicitly religious beliefs, but in broader cultural values that affect national culture. Jesuits and Mainline Protestants, for example, historically increased levels of education. And Protestant values may help explain America’s traditionalism, individualism, and moralization of work. Religions are also shaped by national culture, taking on regional forms. Here’s a buff, Korean Jesus:
Some have also argued that “religion” is mostly a label or an identity, swamped by national culture – think nominal Christians. Or religion may just predict overtly religious beliefs, rituals, and moral attitudes.
For the cultural-group selection theory to work, major world religions should be “super-ethnic” identities, binding people beyond their ethnicity or national borders. That is, those who share a religion living in different countries should be more similar to those who don’t share the religion.
Using a new method for measuring cultural distance called the Cultural Fixation Index (CFst; read more about it here: https://www.michael.muthukrishna.com/beyond-weird-psychology-measuring-and-mapping-scales-of-cultural-and-psychological-distance/), we looked at cultural distance between major world religions in the World Values Survey. What did we find?
CFst are large enough to have competition between distinct cultural-groups of cultural traits, even if you remove overtly religious beliefs. The “People of the Book”—Christian, Muslim, and Jewish people—share cultural similarities. Christians are about as culturally similar to both Jewish and Muslim people as Americans are to Canadians or Australians are to Brits. But just as the United States is similarly geographically distant from Uruguay and Ukraine, but Uruguay and Ukraine are not geographically close to each other, Jewish and Muslim people are a similar cultural distance as people in the United States and the Philippines.
You can take a look at national cultural distance with this app: https://world.culturalytics.com/
As a side note, Buddhists are interesting. They look like Hindus, as fellow Dharmist, but also like Christians, Muslims & Jews.
But of course, these broad generalizations hide a lot of cultural clustering within countries. Fellow citizens more culturally similar than co-religionists in a different country, but foreigners who share a religion are more similar than those of a different religion. And that similarity is stronger if they’re highly religious.
And this broad generalization was true in our data even for places we didn’t expect. Like Muslims in India and Pakistan.
All of this holds true controlling for religious freedom, geographic, linguistic, & genetic distance.
We also looked at the interaction between national and religious culture, showing that non-American Christians are most similar to Americans. America is still a very Christian country and Christianity might therefore be considered the WEIRDest religion (using America as a proxy for WEIRD). That’s consistent with Joe Henrich’s hypothesis for the role of Christianity in creating WEIRD psychological and cultural traits: https://en.wikipedia.org/wiki/The_WEIRDest_People_in_the_World
And finally, non-Americans with no religious denomination are also similar to Americans without religious traits. That’s consistent with other work showing that the US looks like other secular, developed nations except when it comes to traditional religious values.
Considering the limitations of psychology today, I discussed ways in which we can move beyond WEIRD (Western, Educated, Industrialized, Rich, and Democratic) psychology in a global collaborative manner and strengthen the links between basic and applied policy research. I also discussed the importance of historical psychology.
Many thanks to Joseph Henrich for the enthusiastic introduction.
Matthew Syed looks at how kids’ TV got smart, and what we can learn about the developing mind from the program makers who led the way. I discuss the role of cultural evolution in this phenomenon.
Boston, Massachusetts. 1970. A group of mothers and young children assembles outside the offices of the local TV station. It’s the first phase of a fight to improve kids’ TV that would go all the way to the United States Senate. In the late 1960s, children’s television in the US was dominated by cheap cartoons and adverts for sugary snacks. Peggy Charren had something to say about it. She formed a grassroots activism group in her living room with other concerned mothers – Action for Children’s Television. It would become one of the most influential broadcast lobbying groups in history. Peggy was part of a wave of people who were starting to take kids’ TV seriously. From the creators of Sesame Street to psychological researchers like Professor Daniel Anderson who brought science into children’s program-making, Matthew draws out what we can learn from these innovators who know how to create a hit show.
So many great points included from the other guests:
Debbie Charren, Peggy’s daughter, and former schoolteacher and reading specialist;
Robert Krock, Action for Children’s Television’s former development director;
Daniel Anderson, Professor Emeritus at the Department of Psychological and Brain Sciences, University of Massachusetts Amherst;
and Andrew Davenport, creator, writer and composer of In the Night Garden, Moon and Me, and Teletubbies.
In an age of social media ’cancel culture’ might be defined as an orchestrated campaign that seeks to silence or end the careers of people whose thoughts or opinions deviate from a new set of political norms. So if this threat exists for anyone expressing an opinion online in 2021, what’s it like for scientists working in academia and publishing findings that might be deemed controversial?
In this edition of Analysis, I assess the impact of modern social justice movements on scientific research and development.
Is fear of personal or professional harm strengthening conformism or eviscerating robust intellectual debate? Can open-mindedness on controversial issues really exist in the scientific community? Or is rigorous public assessment of scientific findings helping to achieve better, more equitable and socially just outcomes?
So many great points I wish could have all been included from the interviewees who have found themselves in the firing line of current public discourse or who question the severity of this phenomenon and its political motives (in order of appearance):
Long post, but an important topic that helps to resolve controversies such as IQ differences.
Quick summary: We reconcile behavioral genetics and cultural evolution under a dual inheritance framework. A cultural evolutionary behavioral genetic approach cuts through the nature–nurture debate and helps resolve controversies such as IQ.
Business is booming in behavioral genetics. We’re in the midst of a GWAS gold rush. Powerful computers and sequenced DNA of millions has led to an industrious search for SNPs that correlate with a variety of traits. Some even claim the curse of reverse causality has been lifted.
There’s also been a parallel revolution in cultural psychology and cultural evolution. Genes, culture, and the environment have often co-evolved, shaping our species. But the revolutions in behavioral genetics and cultural evolution have largely been independent. But, given the extensiveness of the cultural and culturally-shaped environment, cultural evolution offers an important but typically missing complement to otherwise insightful methodological and empirical analyses within behavioral genetics. Genes and culture are intertwined. For example, our jaws too weak and guts too short for a world w/o controlled fire & cooked food. It’s obvious that lower environmental variation will lead to higher heritability scores. Less obvious is how culture can mask or unmask genetic variation. Or how diffusion and innovation can increase or decrease heritability. Or how to define a single society for the purposes of measuring heritability, without being able to identify cultural cleavages that can lead to Scarr-Rowe type effects: en.wikipedia.org/wiki/Scarr-Row…
Reconciling behavioral genetics & cultural evolution offers insights for differences in heritability between and within populations, differences in heritability across development, and the rise in IQ (Flynn Effect). We’d like a discussion that nuances common interpretations of the nature and nurture of behavior.
First, let’s quickly get a common misinterpretation of heritability out of the way: Heritability is not an index of the genetic basis of a trait nor a measure of the relative contribution of nature compared to nurture. It’s the proportion of phenotypic variance for some trait that is explained by genetic variance. So obviously variability in genes, in environment, and in traits will all matter. A quick illustration: skin pigmentation and UV levels. Genes affect level of skin pigmentation and propensity for tanning instead of burning; ancestral adaptations to UV radiation at different latitudes.
Migration means melanin is mismatched to latitude: Aussies with European ancestry are more susceptible to skin cancer; Europeans with African and South Asian ancestry have higher rates of vitamin D deficiency.
A Gene×Environment approach won’t predict how heritability estimates change over time as non-genetic adaptations compensate for genetic mismatches: fairer Australians wear sunscreen, a hat, & covered clothing; darker Europeans consume vitamin D supplements & vitamind D-rich or fortified foods. Here it’s easier to see that heritability is a function not only of genes, traits, and ecology, but also of an evolving cultural environment. The environment is not an inert backdrop against which genes should be evaluated. It evolves in relation to both genes and ecology.
Four lessons before we continue. The first is obvious to behavioral geneticists, the second sometimes noted, the third and fourth are typically missing.
Lesson 1
There is no overarching, one-quantity heritability of a trait to be discovered. There is no fixed answer to the question, “What is the heritability of skin cancer?”
Lesson 2
Heritability will depend not only on ecology, but also on culture & specifically on diffusion and innovation—both of which can rapidly change and therefore rapidly change heritability estimates.
Lesson 3
Diffusion and innovation are broadly directional. Cultural diffusion of sunscreen, clothing, shade & sunglasses, and cultural innovation toward more effective screening and treatment of melanomas all work to reduce heritability estimates due to a masking effect.
Were any of these an example of culture unmasking genetic effects, such as tanning salons that induce differential risk according to skin pigmentation level, we would have predicted an increase in heritability.
Lesson 4
We might expect a stronger cultural response where ecological and cultural selection pressures are stronger—skin cancer mitigation in Australia but Vitamin D supplementation in northern Europe. Not been tested to our knowledge, but the predictions are clear.
“Which SNPs are associated with skin cancer?” is similarly culturally dependent. Societies where sunscreen use is common, we expect SNPs associated with skin pigmentation to be less predictive of skin cancer compared to societies where this is not the case.
Similarly, we would expect SNPs associated with antioxidant metabolism to be less predictive of skin cancer in societies whose foods are rich in antioxidants—such as in traditional Mediterranean cuisine.
Section 2.2 is on how cultural evolution shapes heritability through diffusion and innovation. We live on the peaks climbed by cultural evolution – human environments have already been shaped by cumulative cultural evolution—functionally overlapping with genetic evolution.
Diffusion and invention can mask or unmask genes. Examples using language, fertility, and schooling.
Language example
If Cantonese or Yoruba (both tonal) spread, heritability of language ability would increase proportional to variation in “tone” genes.
If Norwegian or Russian (both non-tonal) spread in the same population, heritability of language ability would decrease.
Fertility example
Contraception and social values in 20th century unmasked the effect of genes associated with reproductive behaviors and preferences (heritability rose in US). But a one-child policy or rigid childbearing norms masks the genetic effect.
School example
School is a powerful mechanism for cultural diffusion. Heritability of literacy in:
Australia: Kindergarten: 0.84 Grade 1: 0.80
Scandinavia: Kindergarten: 0.33 Grade: 0.79
Why?
Cultural diffusion of literacy.
Australian children begin receiving compulsory literacy instruction in kindergarten, while in Scandinavia the kindergarten curriculum emphasizes social, emotional, and aesthetic development—literacy instruction only begins in Grade 1.
Assessing the genetic basis of literacy without accounting for particulars of curricula on cultural diffusion is a selection bias of unknown magnitude. Note that literacy in the home environment is already shaped by cultural evolution; there is no ‘baseline’ heritability. Heritability is a composite measure that captures both genes and culture. Saying literacy heritability in Scandinavia jumps up to 0.79 in Grade 1 reveals as much if not more about the disseminative power of modern schooling than it does about the genetic basis of literacy. Similar dynamics with innovation. Read about it in the paper.
However, one neglected factor is “cultural clustering”, where even highly useful forms of cultural knowledge may not easily permeate social barriers. Not necessarily ethnic boundaries, also class, wealth, occupation, political alignment, religion, or incidental geographic layout. Greater differential clustering can lead to a cultural Simpson’s paradox (we’ll get to that shortly, but see Section 3.4).
Cultural FST (CFST) is useful for identifying these clusters. You can read more about that paper here: https://www.michael.muthukrishna.com/beyond-weird-psychology-measuring-and-mapping-scales-of-cultural-and-psychological-distance/
Hopefully, you can see the importance of a cultural evolutionary behavioral genetics. We hope this target article will spark a vibrant discussion. But let’s move onto the problems that obscure the effect of culture:
(1) the WEIRD Sampling Problem
(2) the Hidden Cluster Problem
(3) the Causal Locus Problem
And then describe the:
(4) Cultural Simpson’s Paradox that emerges at their junction.
The WEIRD Sampling Problem
The WEIRD people problem? Pretty bad in genetics too. Twin studies: 94% Western: 60% US, UK, Aus; 25% Nordic 6% Non-Western: 4% China, Japan, South Korea, Taiwan
Remainder of the world, i.e. vast majority of humans are the remaining 2%
Same story in GWAS: 88% European ancestry. 72% from just 3 countries: US, UK, & Iceland 20% from Japan, China, and South Korea
From a cultural evolutionary perspective, given (a) cultural environment, (b) coevolution b/w culture & genes, & (c) cultural differences between populations, not surprising that: 1.Polygenic scores don’t translate well across ancestry groups (European scores, 42% in Africa) 2. Polygenic scores are highly sensitive to inadequately controlled population stratification. And so cultural variation and the hidden cluster problem is pernicious.
Hidden Cluster Problem
Cultural clusters (or segregated diversity) typically created by barriers impeding cultural transmission, such as topography, cultural conflict, language, social stratification by class, wealth, etc. Immigrant countries more clustered (Canada > Japan).
Countries whose borders are drawn arbitrarily with respect to the geographic arrangement of cultural groups, for example by colonial administration (many countries in Africa), are also likely to have high clustering. You can use CFST to find them: https://journals.sagepub.com/doi/abs/10.1177/0956797620916782
Note that cultural clustering is not the same as genetic clustering as we explain at length in Section 3.2.2. Indeed, reconciliation between cultural evolution and behavioral genetics requires an update in the way we think about culture.
Causal Locus Problem
Hidden cluster problem describes complexity that exists w/in social groupings. Culture is not an unstructured exogenous variable. Culture is constructive system that accumulates functional adaptations in a directed manner over time. Two key lessons here.
Lesson 1: Genes that make vs genes that break. The more complex a system, the more ways it can fail. Take the history of lighting.
Wood fire can be extinguished in 2 ways Flourescent bulbs have 7 ways to fail LEDs have 30
Faulty O-ring can explode a space shuttle and so on.
There is a fundamental asymmetry: easier to find ways to break the system than ways to explain or improve it. So too for gene function. All your cells have the same bootstrapped code, but they interact with each other, what they create, and their surroundings to create you.
There are many ways these interactions can go wrong. It is easier to identify deleterious genetic mutations than beneficial mutations. The space of failure is larger than the space of success, making genes that break more detectable than genes that make. For example, a single mutation can cause Mendelian disorders such as cystic fibrosis and Huntington’s disease, but no single mutation creates genius. Over 1000 genes have been linked to intelligence.
Each gene only explains a miniscule fraction of variation in intelligence, and the causal mechanisms are unlikely to be straightforward. In contrast to these genes that make, the causal mechanisms behind single gene mutations that cause intellectual disability—e.g. BCL11A, PHF8, ZDHHC9—are relatively well understood.
Increasing nutrition, improving schooling, and removing parasites have positive effects on IQ, but in a society where parasite infection is kept under control, we would not notice that parasite status correlates with intelligence. And by corollary, genes that provide protection against malnutrition, parasites, or pollution would only be positively associated with intelligence in environments where these insults occur. In environments where these insults have been removed, the same genes would not be associated with intelligence, and can even be deleterious, as with sickle cell trait. Not helpful if there’s no malaria.
Genes are functionally masked by cumulative cultural evolution, and we expect that this masking is extensive and systematic. A quick evolutionary and historical example: Vitamin C, the GLO gene, and dead sailors.
Vitamin C is an essential nutrient and its acquisition is thereby an essential biological function. Endogenous synthesis of vitamin C requires a gene called GLO, and GLO is present across most of the animal kingdom. But because vitamin C synthesis is metabolically costly, the gene is inactive in some species that have access to sufficient quantities of the nutrient in their diets. e.g. taxa such as teleost fishes, guinea pigs, many bats, some passerine birds, monkeys and apes.
Anthropoid primates occupy a frugivorous niche, and fruits often contain sufficient vitamin C. Here gene function is offloaded onto environmental resources. In turn, this offloading has behavioral implications. If a species becomes dependent on its environment for vitamin C, both its behavioral range and evolutionary trajectory become constrained by the availability of the nutrient. Humans are a nice example of this.
As our species migrated across the planet, we found ourselves in environments where vitamin C was in short supply. A deficiency of vitamin C causes scurvy—the bane of seafarers until the trial-and-error discovery that certain food items like sauerkraut and citrus could prevent ships from being packed with tired, bleeding, toothless, and eventually dead sailors.
Masking does not necessarily need to be in the direction from culture to genes: genetic assimilation is same process working in the opposite direction, where a trait that is regularly acquired through learning gradually transfers its locus to the genome (i.e. Baldwin effect).
Cultural Simpson’s Paradox
Which leads us to the Cultural Simpson’s Paradox. Causal Locus Problem can confound the measurement of genetic effects due to Hidden Cluster Problem obscured by WEIRD Sampling problem creating a Simpson’s paradox.
Let’s return to the UV example. The melanin-UV mismatch can be masked by the cultural diffusion of sunscreen, especially in regions with more exposure to sunlight. In other parts of the world, the issue is under-exposure to the sun causing vitamin D deficiency. Low vitamin D leads to lack of bone integrity, muscle strength, autoimmune disease, cardiovascular disease, cancer etc.
In US and France, more north you go, the the lower vitamin D levels. Makes sense, right?
But when we compare across Europe, we see the opposite pattern where people in northern countries have higher vitamin D than people in southern countries. What’s going on?
High consumption of fatty fish and cod liver oil in Northern Europe, as well as greater sun-seeking behavior in these countries compared to Mediterranean Europe. These are potent cultural adaptations.
Participants fed the traditional Norwegian fish dish mølje three times over a span of two days had 54 times the recommended daily dosage of vitamin D. The relationship between latitude and Vitamin D goes one way within a country, and the other way between the countries.
If we had been Martian anthropologists who did not know that the populated landmass known as “Europe” can in fact be broken down into sub-units called “countries”, these examples would be standard examples of a Simpson’s paradox.
In these cases, the paradox occurs when we do not know how to partition the higher-order population (Europe) into lower-order units. Fortunately, we can partition continents into countries, but in other cases, the relevant units is not as easily identifiable. Let’s move on.
We now have enough to make sense of puzzles in behavioral genetics such as (1) differences in heritability across socioeconomic levels, (2) differences in heritability across development, and (3) the Flynn effect.
SES: Heritability of IQ is higher among affluent, high socioeconomic status (SES) households than among poorer, low-SES households in some societies, but mixed in others. Why?
One explanation is ‘reciprocal causation’: genes well suited to a task can better nurture their skills in a wealthier environment than in a poorer environment and this is amplified over time. Maybe, but then why don’t we see the effect in Europe and Australia?
Here’s what we think is going on: in the US, the differences between school and home environments among high-SES households is smaller than among low-SES households. US is a land of variance. Factors such as school lotteries can dramatically affect the cultural input.
In contrast, the cultural environment is less unequal in western Europe and Australia, where, for example, high quality schools are available across SES. Where these two explanations make different predictions is for poorer countries.
Reciprocal causation would predict low heritability in poorer countries. We would predict high heritability where there is equal access to similarly poor schools and household conditions, but low heritability if inequality is high.
Incidentally we predict the opposite between human and animal environmental effects due to social transmission. It’s interesting, but not central. Check out Section 4.1.2. Let’s move onto heritability across development.
Heritability changes over the lifespan. Heritability of political orientation is similar for American identical and fraternal twins from middle childhood up to early adulthood. Right around the age at which American children leave home, this pattern is broken.
Drops for fraternal but not identical. We argue this is due to vertical vs oblique transmission and would predict a different drop off for say Italian or Croatian who leave home past 30.
Flynn effect describes the rise in IQ test scores over time. Largest in countries that have recently started modernizing, and smallest in countries that had attained modernization. No consensus to explain it, but given speed genes obviously unlikely.
We argue its caused by a rapid worldwide increase of cultural practices, technologies. Intelligence is about hardware—genes, parasites, pathogens, pollution, and nutrition affecting health and brain development, but also software—our increasingly complex cultural package.
By this account, not only is the idea of a culture-free IQ test implausible, but so too is the idea of culture-free IQ. Lots to say here. Go read Section 4.3.
Home stretch: Cultural Evolutionary Behavioral Genetics. The thrust of our theoretical case is that human psychology and behavior have a large cultural component that has been changing over history.
Most recently our psychology has been shaped by the advent of writing, numeracy, different types of agriculture, the Industrial Revolution, the Internet, and smart phones.
As new adaptive traits emerge, initially those who possess these traits will have an advantage, as in the case of access to new food sources, better healthcare, more efficient technologies, or easier methods of learning.
But eventually the traits will reach fixation in the population through the processes of cultural diffusion, at least until they are unseated by subsequent innovations. We predict that these cultural dynamics are reflected in heritability estimates.
As any geneticist knows, genetic heritability is a function of the variability in the environment, variability in genes, and variability in the phenotype. There is little to predict if the phenotype is homogenous, as in the number of fingers or kidneys.
There is little to predict with if the environment or genes are homogenous. But what is factored into the environment includes not only the physical ecology, but also the cultural environment.
While variance in genes and ecology may be relatively stable, the variance in the cultural environment is continually changing through the processes of cultural evolution. A genetic account of human psychology and behavior must also account for culture and cultural evolution.
Section 5 and the conclusion tie everything together, but I’ll leave you to read it (muth.io/cegh). There’s a formal model with some pretty graphs in the Appendix:
I was selected as one of 11 teams of researchers to receive inaugural awards of the Grand Challenges for Human Flourishing with a project titled ‘What does cultural evolution look like in the 21st century, and how can we use the answer to ensure continued human flourishing?’.
Templeton World Charity Foundation (TWCF) announced the initial investment in a $60 million commitment for bold research that pushes the boundaries of scientific knowledge to help people flourish.
More than 500 teams of scientists from over 350 academic institutions across the world answered the request for ideas, which push beyond traditional measures of physical and mental health to include happiness, meaning and purpose, spiritual well-being and striving in adversity. The 11 awards represent the work of more than 40 researchers at over two dozen institutions and amount to more than $1 million to encourage further exploration of these ideas and the advancement of science in human flourishing.
Some of the questions I hope to tackle include:
What does cultural evolution look like when people are united by a global Internet, but separated by filtered social network feeds?
How does our social learning psychology interpret this information to decide what is true, what others think, and whom we can trust?
What does cultural evolution look like when people separated by geographic and cultural distance regularly interact and even live together in the same country?
How do societies with very different cultural evolutionary histories find common ground to cooperate on global challenges?
Cultural evolution and dual inheritance theory are the closest we have come to a “theory of human behaviour” and “theory of social change”. But so far, we’ve focused our efforts on understanding the past – human origins and human history – rather than understanding the present or preparing for the future. The framework offers answers for what has led to human flourishing thus far, how we’ve overcome challenges on the path toward greater cooperation, and why some societies have diverged from others. I will be helping the Templeton World Charity Foundation (TWCF) strategise about how cultural evolution works in the 21st century. How this framework that helps explain human flourishing can also help ensure continued flourishing—support economic development, strengthen democratic institutions, and catalyse collective action to tackle the challenges of a post-climate changed world.
I am honored to be among this year’s SAGE Early Career Trajectory Award recipients. This Society for Personality and Social Psychology (SPSP) award recognizes scholars in the early stages of their professional careers that contribute to advancing the boundaries of personality and social psychology. Many thanks to my amazing mentors who have supported me over the years and continue to inspire me!
I am honored to be among this year’s Association for Psychological Science (APS) Rising Stars. Many thanks to my amazing mentors who have supported me over the years and continue to inspire me!
This year marks the 150th anniversary of Charles Darwin’s Descent of Man. As part of the celebration, the Center for the Dynamics of Social Complexity (DySoc) organized a series as Outreach for the Cultural Evolution Society: Celebrating the 150th anniversary of the The Descent of Man (http://www.dysoc.org/dom_webinars). I presented the most up-to-date version of the “Cultural Brain Hypothesis, Collective Brains, and the Evolution of Intelligence”. You can watch the talk below:
In an age of social media ’cancel culture’ might be defined as an orchestrated campaign that seeks to silence or end the careers of people whose thoughts or opinions deviate from a new set of political norms. So if this threat exists for anyone expressing an opinion online in 2021, what’s it like for scientists working in academia and publishing findings that might be deemed controversial?
