Peter Richerson: Human Evolution in the Pleio-Pleistocene

The full title is: Human Evolution in the Pleio-Pleistocene: A World Queerer Than We Supposed.

Here Peter is mostly making the case that understanding human evolution requires an understanding of the influence of climate. Cultural evolution gets mentioned, but it is not really the main topic.

Peter Richerson: Cultural Group Selection and the Origin of Institutions and Norms

Boyd and Richerson's cultural evolution vs memetics

Boyd and Richerson's conception of cultural evolution seems to have become on of the most popular ones in academia. It is one of the closest theories to memetics that academics have come up with. As it (correctly) says here: "the biggest difference is a difference in academic lineage". I've written various articles contrasting their views with memetics as I understand it. However, this seems like time for a summary post. Here are what seem to me to be the main "sticking points":

• Terminology. Boyd and Richerson use "cultural variant" while memetics uses the "meme" terminology from Richard Dawkins. "Cultural variant" hides the link to biology in a manner apparently designed to appeal to anthropologists. With "meme" the link to biology is up front and central. As far as I can tell, the terms are functional synonyms - though "cultural variant" is a lot more long winded and a lot less popular.

• Boyd and Richerson seem to see many more differences between cultural and organic evolution than memeticists do. For details of this see the differences remain exaggerated article. To memeticists, Boyd and Richerson seem to not understand the parallels properly. That matters, because understanding the similarities and differences is one of the primary points of the scientific effort to study cultural evolution.

• Boyd and Richerson have put a big focus on gene-meme coevolution. By contrast in memetics, genes typically change too slowly to be worth considering, and the main focus is on the evolution of memes. A related difference is that Boyd and Richerson have mostly been considering events many thousands of years ago. Memetics generally has much more modern concerns. Gene-meme coevolution is a much more complex, difficult and poorly-understood topic than memetic evolution is. Many academics became obsessed with it in the 1980s. It was not a particularly positive obsession. It was rather like trying to fly before you could walk. Impressive, but not terribly sensible.

• Memetics is symbiology-rich. Boyd and Richerson have written a little about symbiology in cultural evolution, but mention it rarely and seem to regard it as an analogy. To a memeticsist, their work often appears to be symbiology-challenged.

• Boyd and Richerson are long-standing supporters of group selection. By contrast, I - and probably most other evolutionists - prefer to look at evolution in terms of kin selection. Group selection appears to have led Boyd and Richerson astray. For example they argued in their 2005 book that group selection did not have a significant effect on human DNA. Now that the equivalence of kin selection and modern forms of group selection is widely understood, this claim appears to be unsupportable.

• Memeticists tend to be Darwinian revolutionaries. By contrast, Boyd and Richerson do not seem to be revolutionaries. Instead, they say:

  We believe that the Darwinian theory of cultural evolution will make contributions across the broad sweep of problems in the human sciences, but the project is one of introducing additional useful tools and unifying concepts rather than an imperial ambition to replace great swaths of existing theory or methods.

  They even contrast their "better mousetrap" with Dennett's "Universal acid". I remember that one of my thoughts on reading "Not by Genes alone" was: how do they make this revolutionary material seem so dry?

On a slightly more positive side, by persistent efforts, Boyd and Richerson appear to be managing something memetics has yet to achieve - namely making cultural evolution respectable in academia. There's still a long way to go here, but their efforts here are welcome.

On the other hand, if it wasn't for them, maybe we would have some real memetics in academia - instead of a feeble and watered-down version apparently designed to appeal to anthropologists. As vocal opponents of memetics, Boyd and Richerson may well have a lot to answer for. I think most students of memes have ambivalent feelings towards their work.

We still need a strong version of memetics to be championed from within academia. My current expectation is that the promise of cultural kin selection will help to open the flood gates on a meme-oriented view of cultural evolution - broadly mirroring what happened with kin selection and genes in the the organic realm in the 1960s and 1970s.

References

• Tyler, Tim (2011) Where Boyd and Richerson differ from memetics
• Tyler, Tim (2011) Why no cultural creatures in academia?
• Tyler, Tim (2011) Against the extended genotype.
• Tyler, Tim (2011) Understanding of cultural symbionts in academia

Richerson and Brown on rival theories

Gillian R. Brown and Peter J. Richerson have a nice 2013 article on the differences between:

• Human Behavioural Ecology;
• Evolutionary psychology;
• Cultural evolution;

Since they are both proponents of cultural evolution the article spends much of its time explaining where the other fields go wrong.

It's a good article, but while reading it, I was reminded of the difference in perspective between what the article describes as cultural evolution and the memetics tradition.

The concerns of memetics seem modern to me, while these authors seem to be mostly concerned with distant prehistory - a poorly-documented era which it is difficult to study.

The article contrasts the idea of an "adaptive lag" (from evolutionary psychology) with cultural evolution's idea that cultural adaptation works quickly to eliminate adaptive mismatch. They say:

Thus, Cultural Evolutionists expect that many types of temporal and spatial mismatches between ancestral human adaptations and their current environments will be solved by Cultural Evolution fairly quickly; for example, the development of protective clothing and shelter technology systems has allowed human beings to survive in environments with extreme low temperatures. Cultural Evolution seems to explain why humans have been, if anything, more successful in the Holocene than in the Pleistocene.

This is perfectly reasonable - but memetics is typically much more interested in the areas of mismatch - where meme and gene interests are not aligned. Mismatch helps to distinguish gene-based theories from meme-based ones. It covers the cases where humans are manipulated by others, using memes - an important case to defend against. Basically, misalignment of interests has the advantages of conflict over cooperation - there's more damage and more newsworthyness.

The authors are aware that memes can be maladaptive. For example, they write:

the risk of acquiring maladaptive information might have increased substantially in modern environments, for example because mass media exposes us to many attractively packaged cultural variants designed by advertisers to increase their sales, not the recipients fitness.

Just so - but memetics focuses on these types of case a lot more.

Other differences are that the authors invoke group section - rather than kin selection - to explain cooperation caused by cultural evolution. Also the article seems symbiology free to me - as though the revolution in our understanding of symbiosis in the 1960s-1980s never happened. An article from someone versed in memetics would surely be full of terms such as "parasite" and "mutualist" to describe cultural symbionts. This article skips over these concepts and terminology - it is symbiology-challenged.

Human behavioural ecology and evolutionary psychology seem like weak competitors to what the authors describe as "cultural evolution" to me. It is plain that these disciplines will need to incorporate theories of cultural evolution if they expect to do very much useful work.

Memetics on the other hand, covers the same subject matter in a similar way - but with considerably different emphasis from these authors. Reconcilliation there is also needed - but it looks like a more challenging prospect to me.

Selfishness != parasitism

There's a longstanding muddle associated with the "selfish gene" terminology of Richard Dawkins. The idea is that genetic selfishness tends to lead to anti-social individual behaviour. This misunderstanding has been transferred by some to memetics. Peter Richerson provides our example of this today:

One of the problems with the meme concept as it evolved is that users of the term focused far too heavily on the selfish potential of memes. But I think it is near to undeniable that cultural variants are sometimes selected to become selfish patthogens along the lines that Dawkins suggested.

Here, Richerson seems to be equating - or associating - selfishness with parasitism. To a memeticist, this is a false equation. Most memes behave selfishly. By that, what is meant that they behave as though they are self-interested agents that act so as to maximize their representation in future generations. Most genes also behave selfishly in this way. That is the meaning of the title of "The Selfish Gene".

Memeticists correctly focused on the selfish potential of memes. Memes are typically selfish - and treating them as such allows you to understand and explain their behaviour. However, selfish genes can reside in deleterious symbionts (like fleas), or mutualist symbionts (like gut bacteria). Selfish memes are the same: they can reside in helpful ideas (such as knots) or unhelpful ones (such as obestity-promoting memes).

Selfishness != parasitism. This is just a misunderstanding of the "selfishness" terminology - when applied to memes and genes.

I've picked on this Richerson quote before - but that was for different reasons.

Peter Richerson: HBES interview

Peter Richerson: Tribal Social Instincts, Gene-Culture Co-Evolution

Peter Richerson on human "tribalism". Peter says:

Culture is a form of inheritance. It is something like genes. We get it from someone else.

This is the central organizing principle of memetics.

Darwin's Business

The Evolution Institute has made a bunch of videos about evolutionary economics:

• Matt Ridley: Trade and Cumulative Cultural Evolution
• Peter Richerson: Cultural Evolution and Business
• Robert Frank: Relative Position In Economics
• Geoffrey Miller: Sexual Selection and Business Ethics
• David Sloan Wilson: A New Evolutionary Approach To Business
• Herb Gintis: Homo Economicus Is Wrong
• David Rose: Moral Behavior and Culture
• Stephen Colarelli: Dogs In The Workplace
• Jonathan Haidt: The Darwin's Business Conference
• Paul Romer: Rules, Technology and Innovation

The videos seem to have arisen from the workshop: Darwin’s Business: New Evolutionary Thinking About Cooperation, Groups, Firms and Societies.

The Evolution Institute's home page says:

What does evolutionary science say about economics? A special issue of the Journal of Economics and Organization Behavior that was produced with the Evolution Institute addresses important issues that impact how we understand economics and daily life. Click here: here for the articles for a limited time.

Several of the talks relate to the topic of this blog: memes and cultural evolution.

Strüngmann Forum proceedings

The proceedings of the Strüngmann Forum on cultural evolution are coming out later this year.

It is edited by Peter Richerson and Morten Christiansen. Publisher's blurb. Amazon link.

Some of the attendees have previously blogged about the conference e.g. D. S. Wilson and Peter Turchin.

It looks as though a lot of effort went into it.

Hopefully, such assemblies and publications will make it harder for cultural evolution naysayers to dismiss the field.

Tim Tyler: Boyd & Richerson, Culture and the Evolutionary Process (review)

Transcript:

Hi. I'm Tim Tyler, and this is a review of this book:

Culture and the Evolutionary Process by Robert Boyd and Peter J. Richerson

This book was published in 1985. It is the best book on cultural evolution from the 1980s. It builds on top of earlier work by Cavalli-Sforza and Feldman, who had outlined a similar approach, in less detail in 1981. Boyd and Richerson do a better job than previous authors did of placing their material in its historical context, and offered a better review of other related material.

However, the book has quite a few problems:

It is full of densely-presented mathematical models. I think that these hinder more than they help. Maybe some people will be impressed by them, but I'm not really among them.

The book introduces terminology for cultural evolution. Much of this has not dated well. It uses the term "guided variation" - where, these days, most people would say "directed mutation". The book uses the term "biased transmission", whereas these days we would just say "cultural selection" or just "selection". Hardly anyone uses the term "biased transmission" these days. The book uses the term "cultural parents" and the term "cultural offspring" - but these are not used refer to memes, but rather to their associated hosts. This does not seem like good terminology to me.

The book is almost entirely free of symbiology. This is unfortunate, since any sensible modern theory of cultural evolution must necessarily be heavily based on symbiology. They do mention the concept at one point. They say:

Horizontal transmission is analogous in some ways to the transmission of a pathogen and Cavalli-Sforza and Feldman have used epidemiological models as a starting point for their development of theory. The item of culture being spread horizontally acts like a microbe that reproduces and spreads rapidly because it is "infective" and has a short generation length compared to the biological generation length of the "host". Fads and fashions and technical innovations are familiar examples.

This material is fine - as far as it goes. However three sentences is not really adequate coverage for this concept. You really need to cover cultural parasites, mutualisms, immunity, arms races - and so forth. Many biologists were still getting to grips with the significance of symbiology in the 1980s. However Cloak and Dawkins had previously managed to present a symbiology-aware version of cultural evolution in the 1970s. Boyd and Richerson failed to pick up on this. What do they offer instead? They say:

This does not mean that cultures have mysterious lives of their own that cause them to evolve independently of the individuals of which they are composed. As in the case of genetic evolution, individuals are the primary locus of the evolutionary forces that cause cultural evolution and in modelling cultural evolution we will focus on observable events in the lives of individuals.

This is not a good approach. It is like saying: to study the evolution of smallpox, we should focus on the human victims. The problem with this is that insufficient attention is given to the smallpox virus. You could say that smallpox exhibits horizontal and oblique transmission between its hosts. It exhibits "biased transmission" - due to different levels of resistance from host immune systems. These processes can all be modeled. While this sort of approach would result in some progress, it seems like a fundamentally misguided way of viewing the situation.

Cultural information exists apart from its human hosts. As well as spending some of its time residing in host brains. It exists in libraries, on discs, inside computer memory, in air vibrations and as radio waves. Libraries can burn down, sounds can suffer from interference, and compute memory exhibits senescence. Culture partly evolves outside its primary hosts. The result is a symbiosis between two different kinds of living and evolving systems. If you focus on observable events in the lives of individuals, you are likely to miss all this material.

Though this book presents a closer link between evolutionary processes in the organic and cultural realms than most previous authors managed, Boyd and Richerson don't really take the links far enough.

The main problems seem to be that, at this stage in their thinking, they didn't appreciate symbiology properly, and they didn't understand that evolution happens within minds, during individual learning - as well as between them, during social learning.

The authors have a section at the very start of their book comparing genetic and cultural evolution. They argue that humans get genes from their parents, but their memes come from a range of individuals. However, humans get viral and bacterial genes from a wide range of individuals as well. This is not really a valid difference between genetic and memetic variation. They argue that meme lifespans are different from host lifespans. However, this is true for DNA genes inside parasites too, and isn't a special feature of cultural evolution. They argue that humans get their genes at birth, while they acquire their culture gradually. However, humans acquire DNA genes gradually as well - it is just that these genes are sometimes inside parasites. They argue that cultural transmission occurs after some development has taken place. Yet this too also happens when acquiring parasites. They argue that cultural variation may be affected by life events, and then transmitted to others. Yet again, this happens with parasites. If you consume antibiotics, you may subsequently transmit antibiotic-resistant bacteria that you have acquired during your lifespan to others.

Boyd and Richerson's list of differences between cultural and organic evolution seems almost entirely invalid. This would not matter, except for the fact that much of the project of studying cultural evolution revolves around the issue of what the differences are. Where cultural and organic evolution exhibit the same dynamics, we can mostly use existing models. The rest of the book is largely devoted to mathematical models of the differences they identified.

While it would be interesting if researchers needed a broad array of new mathematics to model cultural evolution, for the most part, the dynamics of cultural evolution are largely shared with epidemiology and symbiology - and models from these fields can be adjusted to deal with culture with relatively minor tweaks - to cover phenomena such as conformist transmission which have few parallels in the organic realm. What needed doing in the 1980s was strengthening and expanding the models of epidemiology and symbiology to cover culture. Instead what we got was an attempt to drive a mathematical wedge between our models of cultural and organic evolution.

In the book, Boyd and Richerson put in a plea for simple mathematical models. Can their approach be excused on the grounds that they are simplifying? Not really. It isn't "simpler" to develop many unnecessary mathematical models based on illusory differences. Rather it results in increased complication through the proliferation of models. Nor is it simpler to only focus on one symbiont in a symbiotic relationship. The result is a byzantine maze of horizontal and oblique transmission vectors. Best to recognise both partners in the relationship and stick to two types of lineage with pure-vertical transmission within each of them. This is what is done with parasites and symbionts in the organic realm. The cultural realm is no different in this respect.

Overall, this was an important book. It probably wasn't as influential it could have been - since its mathematical models and technical style probably presented a barrier for many readers. Still, most modern workers in the field do cite it, recognising its pioneering role. Since its publication, Boyd and Richerson have continued plugging away at the topic. They have produced a steady stream of papers on the subject - including many valuable ones - along with a few more muddled ones. Despite its virtues, this book's problems - or perhaps the perspective of its authors - seems to have resulted in a bit of a hangover for cultural evolution within academia. Dawkins had clearly presented a framework which was more correct in a number of respects many years before. However, over time, these two camp's relationship increasingly turned into a rivalry. Instead of a synthesis, the result seemed to be tribalism and conflict.

The book was probably the first detailed treatment in academia of maladaptive forms of culture - the insight that cloak and Dawkins originally presented. It pointed out that kin selection apples to memes. It applied runaway selection processes to memes. It modeled memetic conformity. It discussed the possibility of memes sterilizing their hosts and diverting their reproductive resources away from gene propagation and into meme propagation. Overall, there is much of interest in it.

Enjoy,

Peter Richerson and Paul Ekman: Evolution of human communication

2012 interview with Peter Richerson

6:10 has Richerson's discussion of "cultural units". He says:

There's this idea that has been promoted, particularly by Richard Dawkins that inherited systems have to be digital - the way genes are supposed to be - that there have to be discrete units that are potentially infinitely long lived - and Rob Boyd and I think this is not correct actually - you can have "unitless" evolution without any trouble really.

I'm pretty sure this is a misunderstanding. What Dawkins said (in "River Out Of Eden", page 19) was:

Only a digital genetic system is capable of sustaining Darwinism over eons of geological time.

The idea that I think Dawkins was getting at here is that evolving systems "go digital" after a little while, and discover the advantages of digital transmission. Genes went digital this before DNA was invented, and many types of meme went digital before computers were invented - in what is known as the digital revolution. They key driver of these transitions is attaining better copying fidelity - and thus gaining the ability to maintain the integrity of a larger genome.

Richerson attacks the idea that everything that is inherited is digital - but that claim seems to be a very silly one. I don't think that is a claim that Dawkins ever intended - or would endorse. Indeed, Dawkins himself gives examples of low-fidelity cultural transmission in the same chapter, namely: audio tape recorders and photocopying (see page 16).

Peter Richerson and Hal Whitehead - The Rise and Fall of Cultures

Peter Richerson and Hal Whitehead - The Rise and Fall of Cultures

Peter Richerson is up first. Hal Whitehead starts 30 minutes in. Then it is back to Peter Richerson 59 minutes in.

The main topic seems to be the collapse of societies.

Culture-Gene Interactions in Human Origins

Features:

• Alison Brooks - Origins of Modern Human Behavior;
• Peter Richerson - Culture-led Gene-culture Coevolution;
• Anna Di Rienzo - Human Adaptations to Diverse Environments;

Features:

• Gregory Wray - Genomic Basis for Dietary Shifts during Human Origins;
• Sarah Tishkoff - Adaptations to Human Adult Milk Intake;
• Henry Harpending - Ongoing Evolution in Humans;

Features:

• Marcus Feldman - Genetic Impact of Culturally-Based Mating Systems;
• Kristen Hawkes - The Grandmother Hypothesis and Rates of Aging;
• Mark Aronoff and Carol Padden - Do Genetic Differences Affect Language Evolution?;

Update: There's now also a YouTube playlist with all the videos in it.

Peter Richerson - cultural evolution video from Darwin 2009

The title is: Not by genes alone: Darwinian methods for the study of culltural evolution.

Expert Peter Richerson goes over the history and development of cultural evolution. Part of "Darwin 2009" at Stony Brook University - and probably part of the Darwin 200th & 150th celebrations.

It's a nice introduction, but, inevitably, I have a feq quibbles:

• Peter compares variation in human genetic information with variation in human memetic information, and concludes that the variance in the memes is much greater. That's all very well, but it isn't really a fair comparison. Memes are cultural symbionts - and so one should compare them with organic symbionts. Variation in the combinations of persistent viral, bacterial and fungal symbionts is pretty large in humans.

• Peter brings up the issue of inheritance of cultural acquired traits, but soon says that might not be such a big difference after all, though according to him we'll have to wait and see about that. The situation is that dogs pass on fleas they acquired during their lifespan to their offspring - much as humans pass on ideas they acquired during their lifespan to their offspring. Both the fleas and the ideas can mutate inside their hosts - and those changes are passed on as well. The organic and cultural realms are pretty similar in these regards.

• Peter says that you can get memes from multiple sources - not just your parents. However, this isn't really much of a difference from the organic realm either, since you can get parasites from your offspring, peers, aunts and uncles as well - not just your parents.

• Peter says that culture exhibits "biased transmission" - where we choose what memes we acquire. He says we are smart shoopers in the space of ideas - and are not "passive recipients, the way we are of our genes". However, humans are not passive recipients of the genes of organic symbiotes - any more that they are of the memes of cultural symbionts. For example, if you want to avoid a sexually-transmitted diseases, you can abstain, or use barrier contraceptives. The "passive recipient" model of genetic transmission is simply mistaken.

There's a pattern to these issues. They all apparently involve a failure to fully appreciate the idea of symbiosis and apply it to the cultural realm. Peter Richerson does know about symbiosis, and has proved it in his writings by comparing cultural entities to sumbionts, viruses and bacteria. However, for some reason, the implications don't always seem to filter through.

Does monogamy support cultural group selection?

The latest paper from Henrich, Boyd and Richerson is called "The puzzle of monogamous marriage". It ponders the puzzle of monogamous marriage - how monogamy has spread while wealth inequality has increased.

Much of the paper is devoted to showing that monogamy is good for society-level fitness. They invoke cultural group selection to explain monogamy's spread.

Slavery seems like a suitable point of comparison. This is also widely banned - despite the fact that the richest might be expected to benefit most from it.

Wife inequality is seen as more of a moral issue than wealth inequality - and technological growth independently fuels wealth inequality.

Is the spread of spread of monogamy down to cultural group selection? I'm sceptical. It is true that in the democractic, religious and political revolutions and invasions that have spread monogamy a whole buch of memes gets supressed at once. However, describing this as being a form of group selection seems a bit controversial. A whole bunch of birds went extinct at once when mammals reached New Zealand. However, few would describe that as being a form of group selection. The invading animals wiped out the natives bacause they were fitter than them - not because of group-level effects.

Looking at large groups of memes going extinct during a major mass extinction event isn't terribly good evidence for cultural group selection, IMHO. In general, one group of organisms systematically wiping out their neighbours is just evolution as usual. Group selection - at least of the type that is controversial among biologists - is a more demanding concept than this.

The outcome shows that the monogamy meme bacame fitter as civilization progressed. If it could additional be shown that monogamy lost out to polygamy within groups, that would then qualify as evidence for group-level selection. However, the paper doesn't do that, and the idea that the polygamy meme wins within groups is probably simply false. In which case, group selection is not clearly needed as a hypothesis to explain the results.

A simple explanation for monogamy is democracy. Monogamy is deleterious for 90% of males and probably most females too. The few males it benefits may be powerful, but they are simply out-flanked by the rest of society. This explanation is simple, obvious - and it doesn't invoke group selection.

Memetic altruism is the most obvious thing to look for if looking for evidence favouring cultural group selection. At the moment, people see things that aren't explained by existing theories of altruism, and then invoke forms of group selection. However, it seems to be that this happens largely because they don't have a decent list of the known causes of human altruism. That seems to be largely because of a widespread incomplete understanding of memetics. Account properly for the existing known causes of altruism and group selection theories have a lot less work to do.

Update 2012-01-31: Razib Khan is sceptical about the group selection too.

The evolution of supposedly-altruistic punishment

I am pretty sceptical about many of the proposed applications of cultural group selection. It seems as though most of the features which advocates of cultural group selection propose can be explained more simply in other ways.

For example, the paper entitled The evolution of altruistic punishment explains the origins of human punishment using a model of cultural group selection.

However: there are many individual-level benefits to punishing others - in particlar, punishment is a high-status activity, which increases the punisher's rank at the expense of the rank of the recipient of punishment. Punishing others thus signals high status and improves your reputation - which may produce future benefits.

The finding that some people still expend resources punishing in anonymous one-shot interactions is probably best explained largely by resource-limited cognition - in conjunction with the unnatural nature of such interactions.

References

• Boyd, Robert, Gintis, Herbert, Bowles, Samuel and Richerson, Peter J. (2003) The evolution of altruistic punishment
• dos Santos M, Rankin DJ and Wedekind C. (2011) The evolution of punishment through reputation
• Rockenbach B, Milinski M. (2006) The efficient interaction of indirect reciprocity and costly punishment
• Nicolas Baumard (2012) The evolution of cooperation: from networks to institutions
• Francesco Guala (2012) Reciprocity: Weak or strong? What punishment experiments do (and do not) demonstrate

Memes in "The Origin and Evolution of Cultures"

Going through "The Origin and Evolution of Cultures" - I find that it is pretty saturated with the "m" word - much of it apparently uncritical.

There are some interesting critical bits which I hadn't seen elsewhere. Boyd and Richerson say:

On the one hand, we have great sympathy with the views of the ‘‘universal’’ Darwinists like Daniel Dennett, Robert Aunger, and Susan Blackmore, who, following Richard Dawkins, employ the term to stress the analogies between genes and culture. On the other hand, we have several worries. One is academic punctilio. When Dawkins (1976) coined the term meme, he quite frankly admitted that he had done no scholarship in the social sciences. Fair enough in the context of a trade book, but, in fact, another pioneering universal Darwinist, Donald Campbell (1965, 1975), had done significant work on cultural evolution by 1976. Lucca Cavalli-Sforza and Marc Feldman (1973) had already published their pioneering formal models of cultural evolution.

So: Dawkins wasn't first. He realised that - citing Cavalli-Sforza and others at the time. That criticism doesn't seem very "substantial". They go on to say:

[A] more substantive problem is that the analogy between genes and culture is not very deep. The two are similar in that important information is transmitted between individuals. Both systems create patterns of heritable variation, which in turn implies that the population-level properties of both systems are important. Population-level properties require broadly Darwinian methods for analysis. But this just about exhausts the similarities. The list of differences is much larger. Culture is not based on direct replication but upon teaching and imitation. The transmission of culture is temporally extended. It is not necessarily particulate. Psychological processes have a direct impact on what is transmitted and remembered. These psychological effects can produce complex adaptations in the absence of natural selection. Users of the meme concept seem to us to believe that it does more work than it really does.

My perspective is rather different. If we just stick to the direct link between memes and genes, both exhibit: heredity, drift, selection, linkage, hitchhiking, expression, gradualism, and extinction.

However, that isn't reallythe correct way of looking at things. Rather there's a deep link between cultural and organic evolution. Both exhibit heredity with variation and selection - and in a benign environment, much follows from that - including cumulative adaptation, symbiosis, parasites, mutualism, drift, ontogeny, phylogeny, linkage, hitchhiking and devolution. The link between genes and memes is just one aspect of a much deeper set of features shared between cultural and organic evolution. Similarly there's a relationship between male and female human bodies. Male breasts are not the same as female breasts, but we know that are equivalent in a deep sense - because of all the other links between male and female bodies. It would be bad practice to just focus on the features of one organ - and then reject the link because of percieved differences - male and female breasts are homologous structures. So it is with memes and genes. There are deep links between organic and cultural evolution. After taking those into account, genes map onto memes.

As for the supposed differences Boyd and Richerson list:

• The transmission of organic parasites and mutualists can be "temporally extended" too;
• Psychological processes impact organic evolution too - for example via sexual selection;
• Psychology producing complex adaptations mostly happens when the complex adaptation has previously been produced elsewhere via a selective process - or when a selective process goes on in the brain. The other cases are more like the way a footprint is an adaptive fit for a foot (such processes are not confined to human culture). Overall, this isn't really much of a difference.

That leaves: "Culture is not based on direct replication but upon teaching and imitation." That's sometimes true - though it is worth noting that probably the vast majority of human culture (in terms of bits) is copied using computer systems with extremely high copying fidelity. However, the general idea is that copying occurs - i.e. Shannon mutual information between the copies is created. The details of how that happens can be a bit different. Cultural heredity is not necessarily exactly the same as organic heredity - just pretty similar.

Another thing they say is:

We believe that the Darwinian theory of cultural evolution will make contributions across the broad sweep of problems in the human sciences, but the project is one of introducing additional useful tools and unifying concepts rather than an imperial ambition to replace great swaths of existing theory or methods.

I think these fellows are within the anthroplogy department - so perhaps they are being polite. The social sciences are long overdue for a pretty spectacular and disruptive Darwinian revolution. Not too much pre-Darwinian biology survived Darwin's transition. Perhaps the social sciences will fare better - because they are older and wiser - but surely we can already see a large pile of dirty laundry that just needs throwing out.

References

• Richerson, Peter J. and Boyd, Robert (2005) The Origin and Evolution of Cultures.
  
• Tim Tyler (2011) Memes in Not by Genes Alone.
  

Understanding of cultural symbionts in academia

Many modern academic students of cultural evolution seem to share a common problem with understanding how cultural evolution operates. Though some pay lip service to the idea, they don't seem to fully appreciate that culture's relationship with human hosts is a symbiosis.

Some quotes (some of which I have discussed before) illustrate the syndrome:

Kevin Laland and Gillian Brown, Sense and Nonsense (2004, p.253):

Social transmission can occur vertically (that is, from parents to offspring), obliquely (from the parental to the offspring generation; for instance, learning from teachers or religious elders) or horizontally (that is, within-generation transmission such as learning from friends or siblings). Of course, genetic inheritance is exclusively vertical and hence, as social transmission frequently occurs through some combination of these modes of information transmission, cultural evolution may commonly exhibit commonly exhibit quite different properties from biological evolution.

Paul Erlich The Evolution of Norms (2005):

Among humans, genes can only pass unidirectionally from one generation to the next (vertically), normally through intimate contact. But ideas (or “memes”) now regularly pass between individuals distant from each other in space and time, within generations, and even backwards through generations. Through mass media or the Internet, a single individual can influence millions of others within a very short period of time.

William Durham (1991, p.193) says:

genes usually cannot be transmitted independently of the reproduction of their carriers. This constraint obviously does not apply to memes.

Peter Richerson, in The Evidence for Culture Led Gene-Culture Coevolution: The Naturalization of Culture or the Culturalization of Human “Nature”? (2011) wrote:

We do know that culture is most ungene-like in many respects. Culture has the principle of inheritance of acquired variation (what one person invents another can imitate). We are not necessarily blind victims of chance imitation, but can pick and choose among any cultural variants that come to our attention and creatively put our own twist on them. we don’t have to imitate our parents or any other specific individuals but can always be open to a better idea, or own invention or someone else’s.

Alex Mesoudi, Cultural Evolution (2011) has a similar passage:

One of the more obvious differences between cultural and biological evolution involves the potential transmission pathways each involves. Genetic inheritance is often thought of as being exclusively vertical and biparental, with genetic information transmitted in equal amounts from two parents to a single offspring. In culture, on the other hand, one can learn beliefs, ideas, skills, and so forth, not just from one's biological parents (termed "vertical cultural transmission"), but also from other members of the parental generation ("oblique cultural transmission") and from members of one's own generation ("horizontal cultural transmission").

...though Mesoudi continues by acknowledging:

In fact many of these pathways of cultural transmission have parallels in biological evolution.

...although he fails to mention any of the key phenomena of mutualism, partasitism or symbiosis.

Most of the material above is completely wrong. Symbionts (parasites and mutualists) commonly pass "horizontally" between humans. Parasite genes are shared horizontally by kisses, sex, holding hands and sneezing. Mutualist symbionts and their genes are shared between humans at gardening shops, farms, seed shops and fruit shops. Oblique transmission and transmission "backwards" - down the host generations - work in a similar manner. It should be a matter of acute embarrassment among theorists of social evolution to have missed this.

Such symbiont exchange is by no means confined to humans or other creatures with culture - it occurs ubiquitously in the animal kingdom.

In my experience, many of the misunderstandings of memetics actually turn out to be misunderstandings of how biological evolution works. This example is a case in point.

These academic students of cultural evolution usually go on to say that - because of these differences, we need new models to deal with the situation - and then they go on to develop elaborate extended genotype models to deal with the situation. No! That is not how science is done. The existing models of organic symbiosis handle all these cases just fine. We do not need a raft of new models just to deal with the case of organisms whose genes happen not to be made out of DNA.

Mesoudi's defense of this practice reads:

Nevertheless, most quantitative models of genetic inheritance are indeed based on the assumption of vertical inheritance, making it necessary to construct models tailored specifically to the cultural case.

Not everyone in academia gets this wrong. David Hull, for example was pointing out this mistake back in 1988:

In this connection, commentators often state that biological evolution is always vertical whereas conceptual evolution is likely to be "horizontal". By this they mean that the transmission of characteristics in biological evolution is always from parent to offspring (ie, inheritance). Characteristics always follow genes. In point of fact, biological evolution is not always vertical, even when characteristics follow genes. For example, it is horizontal when bacteria, paramecia, etc. exchange genetic material. Horizontal transmission can even be cross-lineage, as when viruses pick up genes from an organism belonging to one species and transmit them to an organism belonging to a different species.

There are a few cases of recognition of symbiosis:

Most mathematical models of cultural evolution derive from epidemiology. The terminology of "horizontal transmission", "vertical transmission" and "oblique transmission" comes from epidemiology. Epidemiology itself is mostly - though not exclusively - concerned with symbiosis.

Boyd and Richerson (1985) have three sentences on symbiosis. They say:

Horizontal transmission is analogous in some ways to the transmission of a pathogen

...and...

The item of culture being spread horizontally acts like a microbe that reproduces and spreads rapidly because it is "infective" and has a short generation length compared to the biological generation length of the host. Fads and fashions and technical innovations are familiar examples.

Boyd and Richerson (2005, p.165) has a paragraph on symbiosis:

The nonparentally transmitted parts of culture are analogous to microbes. Our immune system evolved to kill microbial pathogens but it also allows us to acquire helpful symbionts. As we know all too well, microbial pathogens are common, despite the sophistication of the immune system. One reason is that we are not the only players in this game. Natural selection helps parasites trick our immune system. Since microbial populations have short generation times and large populations, parasite adaptation can be very rapid. The psychology of social learning is like an immune system in that it is adapted to absorb beneficial ideas but resist maladaptive ones. And, like the immune system it is not always able to keep up with rapidly evolving cultural “pathogens.”

This section is pure memetics. They also implicitly endorse symbiosis in their section on "selfish memes" (p.153-154).

In "The Role of Evolved Predispositions in Cultural Evolution" they say:

An empirical study of the spread of heroin addiction describes the close resemblance of its dynamics to the spread of disease that requires intimate contact (Hughes and Crawford 19721. Addiction is spread along chains of close friendship. Addicts remain infectious only in the early stapes of addiction, while the p1easurabte aspect of the drug still outweighs the manifest disability of advanced addiction. Only a limited population of susceptible individuals is at risk of acquiring the addiction even if exposed. Many simple epidemiological principles probably apply to pathological cultural traits - e.g., parents notice that the incidence of minor microbial infections and various obnoxious habits in children increase together when they first go to school. Crowded classrooms of young susceptibles are the ideal environment for the spread of pathogens of both types by horizontal transmission among the children!

There's a similar section in their paper: "Built For Speed, Not For Comfort".

...and there is a fairly specific endorsement of the idea from Peter Richerson here:

I think it is near to undeniable that cultural variants are sometimes selected to become selfish pathogens along the lines that Dawkins suggested. Since some cultural variants can spread rapidly among people, as in the case of fads, they rather resemble the life cycle of a viral or bacterial pathogen.

Cultural group selection: not so special

Many enthusiasts for the idea that culture evolves also seem to favour the idea of group selection.

Ed Wilson has returned to the "group selection" camp in recent years. David Sloane Wilson promotes both cultural evolution and group selection.

Something called "cultural group selection" is promoted by Boyd, Richerson, Mesoudi, Henrich, Gintis and Nesse as being a significant force which has supposedly helped to shape human ultrasociality.

Many of these authors claim that cultural group selection is dramaticallly different from group selection in the organic realm. For example, Boyd and Richerson (2005) write:

selection between large groups of unrelated individuals is not normally an important force in organic evolution. Even very small amounts of migration are sufficient to reduce the genetic variation between groups to such a low level that group selection is not important. However, as we will explain below the same conclusion does not hold for cultural variation.

This article argues that "cultural group selection" actually closely mirrors group selection acting on parasites in organic evolution.

Enthusiasts for "cultural group selection" claim that cultural evolution acts to rapidly create between-group differences and jelps to prevent gene flow between groups. The between-group differences may also result in one group having a selective advantage. It is conjectured that these differences are sufficient to overcome the problems usually associated with group selection in the organic realm.

However, in the organic realm, evolution of pathogens also acts to rapidly create differences between populations. Pathogens can also cause between-group differences in fitness. This was seen (for example) during the European invasion of North America - where smallpox alone killed 25% of the Aztec population and between 60% and 90% of the Inca population.

One of the mechanisms proposed by Mesoudi and Jensen (2010) that would act to assist cultural group selection is that migrants adopt the social norms of their new group - acting to preserve group variation.

Migration is also a big problem for genetic group selection: in many group-living species one sex typically disperses out of the group, reducing between-group genetic differences. In humans, however, migrants often acquire the social norms of their new cultural group, maintaining between group cultural variation and consequently allowing cultural group selection to act.

However, much the same thing happens in the organic realm as well: migrants go on to contract the parasites of the groups they migrate into.

Sometimes migrants successfully introduce parasites into their new group. However that happens with culture too - migrants can carry beneficial ideas and inventions that subsequently spread like a plague through the new group.

Mesoudi and Jensen (2010) propose that the evolution of modern corporations may exhibit a form of group-level selection on human culture. However, there employees regularly drift between organisations, carrying skills and knowledge with them. NDAs and employment contracts attempt to prevent such losses, with limited success.

Corporations do represent large-scale cultural entities that compete with one another for human resources. However, flu strains also compete with one another on a large scale for access to human hosts. Just as employees of two different corporations may attend the same Masonic meetings, and the same bridge club, so hosts of different strains of flu virus may be infected weith different strains of warts virus and different strains of syphylis.

The broad equivalence between the cultural and organic realms in this area should come as no surprise for those who are already accustomed to treating culture as composed of rapidly-reproducing symbionts with "genes" which are not made out of DNA.

Another issue in this area concerns whether group selection on culture (or parasites) results in group selection on the level of the DNA genomes of their hosts. Between-group differences, sharper group boundaries and differences in fitness between groups may result in the deaths of host groups, along with the deaths of their culltures and parasites.

However, it is fairly common for invaders to spare native women. Also, it seems implausible that between-group migration rates are low enough to prevent individual-level selection swamping group selection when considering only DNA inheritance. Group selection in the human DNA-gene pool is probably a fairly minor force.

Are there differences between groups of humans with different cultures and groups of humans with different parasites which are relevant to the issue of group selection? Yes: culture acts as visible marker which acts to distinguish different groups. That may make the boundaries between groups crisper, and reduce gene flow between them. Parasites probably do that to a much reduced extent. Immigrants are less clearly marked out by their different parasites than by their different cultures - since their parasites are quite often invisible latent infections. They might hesitate to enter new groups through fear of the group's parasites, though. Similarly, groups might reject imigrants out of concern for acquiring their parasite load. However, xenophobia based on cultural cues is probably a more intense force.

Proponents cite conformity and punishment as mechanisms which stabilise groups so they act as independent units. However, such forces apply mainly within the moral realm - and not to (say) the spread of innovations. Some aspects of culture are more likely to spread between groups - and are less likely to be subjected to group-level selection forces. Spread of innovation is one of the main factors strong enough to produce significant group-level fitness differences. These issues are probably not major difference between the organic and cultural realms as far as group selection goes. In conclusion, the "cultural group selection" enthusiasts appear to be greatly exaggerating the differences between the cultural and organic realms. Differences between the applicability of group selection to the two domians are probably mostly fairly minor. If culture is to be used to argue that group selection is an important force, much the same argument applies to parasites in the organic realm.

References

• Mesoudi, Alex & Jensen, K. (2010) Culture and the evolution of human sociality. In: The Oxford Handbook of Comparative Evolutionary Psychology, edited by J. Vonk & T. Shackelford. Oxford, UK: Oxford University Press.
• Richerson, Peter J. and Boyd, Robert (2005) Not by Genes Alone: How Culture Transformed Human Evolution. University of Chicago Press: Chicago, IL.
• Henrich, J. (2004). Cultural group selection, coevolutionary processes and large-scale cooperation. Journal of Economic Behavior and Organization, 53, 3-35.
• Henrich, Joseph, Boyd, Robert and Richerson, Peter, J. (2011) The puzzle of monogamous marriage.
• Gintis, H. (2000). Strong Reciprocity and Human Sociality.
• Boyd, Robert and Richerson, Peter J. (2010) Transmission coupling mechanisms: cultural group selection. Philosophical Transactions of the Royal Society (B), 365, 3787-3795.
• Lehmann, Laurent, Feldman, Marcus W. and Foster, Kevin R. (2008) Cultural Transmission Can Inhibit the Evolution of Altruistic Helping.