Massimo Pigliucci - Is Cultural Evolution a Darwinian Process?

This post comes from Rationally Speaking, a blog by Professor Massimo Pigliucci, a philosopher at the City University of New York. In this post, he discusses a recent paper by Chris Buskes, published in Philosophia, entitled “Darwinism Extended: A Survey of How the Idea of Cultural Evolution Evolved.” Buskes supports a Darwinian model of cultural evolution, Pigliucci, however, does not. It's an interesting discussion.

On my end, I have trouble with the accepted version of Darwinian evolution, specifically that variation is random. The evidence is mounting that many (if not most) variations--including those leading to new species--are the result of epigenetic changes, and these most often occur in response to environmental factors or conditions. This is not random.

Further, where Darwinian evolution sees unintelligent selection, the existing evidence seems to indicate--even in a survival of the fittest model--that selection is not only intelligent, it is directed (and this need not invoke an unseen deity or any such nonsense), and it seems to favor increasing complexity (sometimes) and greater diversity (often).

On the other side of the ledger, I would argue that cultural evolution is less intelligent and less directed than Lamarck would have us believe.

Let's look at the Renaissance as an example.

Changes in land laws and social norms (social environment) led to changes in life conditions, which resulted in a flourishing of new technologies and increases in food production and medical knowledge. This resulted in healthier citizens with longer lifespans (biological existence), the development of wealth and a larger leisure class (social structures), who desired beautiful art and sculptures, music and plays, and other elements of culture (shared experience). All of these changes led to additional growth of inner experience (emotions, knowledge, spirituality, and so on--individual psyche). All of these developments, over a few centuries, led to the Enlightenment--an evolution in culture that took a couple of more centuries to trickle down into the general population.

This scenario is an example of how human beings are complex adaptive systems - and that cultural evolution is both a cause and effect. It's much more complex than any of these limited perspectives allow for.

Is cultural evolution a Darwinian process?

by Massimo Pigliucci
Monday, March 11, 2013

The “Darwinian” theory of evolution is here to stay. I used the scare quotes to refer to it in the previous sentence because the current incarnation, known as the Modern Synthesis (and incorrectly referred to as “neo-Darwinism,” which actually was an even earlier version) is significantly more sophisticated and encompassing than the original insight by Darwin. Indeed, my opinion — which is certainly not universally shared — is that evolutionary biology is currently undergoing another gradual but significant change, referred to as the Extended Synthesis, that will expand its domain of application and explanatory tools even further.

But will it expand them to the point of providing us also with a coherent theory of cultural evolution? Chris Buskes, in a recent paper published in Philosophia and entitled “Darwinism Extended: A Survey of How the Idea of Cultural Evolution Evolved” seems to have no doubt that the answer is in the affirmative. I am not so sure.

Buskes’ paper is worth reading in its entirety, as it is a lucid survey of a number of ideas attempting to connect Darwinism and cultural evolution, including concepts like niche construction, gene-culture co-evolution and, of course, memetics.

The basic argument advanced by Buskes is that cultural evolution is best thought of as a Darwinian process because it shares the fundamental elements of Darwinian processes. These elements have been laid out in a famous paper by geneticist Richard Lewontin back in 1970. The list looks like this:

• Variation: members of a population that evolves in a Darwinian fashion show some degree of phenotypic differences in a number of traits.
• Selection: some individuals are more successful than others at surviving and reproducing, because of their phenotypic characteristics.
• Inheritance (which Buskes calls “replication”): there is a statistical correlation (regardless of specific mechanism) between the fitness-enhancing characteristics of the parental generation and those of its offspring.

While this basic summary — which Buskes refers to as “Darwin’s formula” (though, as such, it’s really Lewontin’s formula) — has been criticized for being actually too bare-bones (see, for instance, the discussion in Okasha’s excellent book on multi-level selection theory). As we shall see, my problem with Buskes’ conclusion is in part a result of the excessive minimalism of the formula.

Of course, people have proposed before that Darwinian evolution is “substrate neutral” and that its principles can be universalized. Dawkins’ and Dennett’s ideas about memetics (which do enter, with caution, into Buskes’ considerations) are an obvious example. More recently, even chemists like Addy Pross and physicists like Lee Smolin have gotten into the fray, proposing extensions of Darwinism to chemistry and cosmology respectively (here and here is why I disagree).

Let’s take a quick look at the building blocks of Buskes’ argument, focusing in the end on why I think he got close, but eventually missed the mark.

After introducing “Darwin’s formula” Buskes move on to make the point that human beings are highly cultural animals, very different in this from pretty much any other species on earth (he refers to culture as a “major transition in evolution,” a popular term these days, though one that has a bit too much of a teleological flavor for my taste). Which means that there really is something to explain above and beyond the basic biology of being human. No argument from me there. The problems begin when Buskes makes the move of declaring (plausibly, but with scant hard evidence) culture to be a “complex adaptation,” immediately making the evolutionary psychology-like leap that it therefore could have happened only by way of Darwinian selection. This, in my book, counts as a pretty massive begging of the question.

Buskes’ next move is to introduce the concept of niche construction (from evolutionary ecology) and to present it as a way to understand cultural evolution. Niche construction is a way to think about repeated gene-environment interactions going beyond the simple standard model that sees environments as posing a “problem” for the organism that evolution “solves” by mutation and natural selection. The classic example of niche construction is beavers’ dams (also an example of what Dawkins called an “extended phenotype”), structures that dynamically alter the environment not just of beavers but also of other species in the local ecological community, thereby introducing new selective pressures, which in turn act also on beavers’ phenotypes and behaviors, and so on. As interesting as these ideas are, it isn’t at all clear what work the concept of niche construction actually does — other than as an interesting metaphor — in explaining the transition from straight biology to culture in human beings.

Indeed, it is here that the weaknesses of Buskes’ approach begin to appear evident to the attentive reader. This is the section in which he cites the now classic work of people like Cavalli-Sforza, Feldman and others on gene-culture co-evolution. The thing is, if we are meant to take that (interesting, pioneering) work as a way to theorize about cultural evolution, we are at a dead end. Most of those papers are from the 1970s and ‘80s, with very little having been done since. That approach looks increasingly like what philosopher of science Imre Lakatos famously called a “degenerative” research program, i.e. an approach that seemed once fruitful but that has since ceased to bear fruits.

Buskes then moves to an interesting analysis of how biological and cultural evolution might be connected. He examines two broad frameworks, neither of which he finds entirely satisfying. First, there is the sociobiology / evopsych inspired model according to which — as E.O. Wilson once famously put it — biology keeps culture “on a leash.” Here the locus of explanation is the pre-modern (for some reason, largely Pleistocene) evolution of Homo sapiens, with modern human behavior explained either as still adaptive but rooted in the past, or as recently turned into a maladaptation because of the sudden decoupling of culture and biology in post-Pleistocene times. Second, we have the memetic model of extensive decoupling of culture from biology, where new entities (the “memes”) compete for space in our brains, regardless of their effects on the fitness of their “hosts” (i.e., us).

Buskes is sympathetic to aspects of both models, but is also aware of many of the criticisms they have received. Frankly, I don’t think he goes far enough on his critical path on either count. It would take too much space (and it would bring us significantly off course) to rehash my problems with both evopsych and memetics, but you can find a summary here and here, respectively.

[On memes, however, I can’t resist two of my favorite quotations. The first one is by my colleague and sometime antagonist, evolutionary biologist Jerry Coyne, who aptly said: “{Memetics is} completely tautological, unable to explain why a meme spreads except by asserting, post facto, that it had qualities enabling it to spread.” The other one, even more damning, is by biologist Jeffrey Schloss: “It is not entirely clear how it is that positing unseen and undefined entities that infect human minds by unassessed processes involving the entities’ own quest for transmission and that cause people to do things that transcend their genetic imperatives is fundamentally different from medieval demonology or, in any case, qualifies as an empirically grounded explanation in terms of natural causes.” Ouch.]

We finally get to the crux of my disagreement with Buskes, which comes into focus when he gets around discussing the two most common (and interrelated) objections to thinking of cultural evolution as a Darwinian phenomenon: the apparent “directedness” of cultural evolution and its “Lamarckian” character.

In terms of directedness, the idea is obviously not that the outcome of cumulative cultural evolution looks teleonomic, as the appearance of teleonomy is typical of Darwinian biological evolution too. The eye, to pick on the standard example, appears to have been designed for the purpose of seeing. In reality, there was no such long-standing design or pre-ordained tendency, only a large number of haphazard mutation-selection cycles, which however did bring about the function of the eye as we currently understand it. In fact, years ago I have used this sort of insight to argue that evolutionary biology maps conceptually very well onto the famous four Aristotelian causes, including the so-called “final” cause, which answers the question “What is X for?” The answer is, of course, different from the one Aristotle would have provided, but such is progress in human understanding.

So, the issue here is not one of directedness of the outcome of evolution, but of the source of variation. Contra Buskes, a cardinal tenet of the Modern Synthesis (and indeed of the original Darwinism) is that mutations — the ultimate source of novelty in evolution — are random with respect to fitness outcomes. It is important to understand this point. Molecular biologists have long discovered that mutations are not random in the sense that they all appear with the same frequencies, regardless of genomic localization. There are “hot spots” along different chromosomes in different species, and some structural changes in DNA are more likely than others to occur because of the three-dimensional conformation of DNA. But — despite the occasional claim to the contrary — there is no convincing evidence that favorable mutations (in a given environment) are more likely to occur than unfavorable ones. Should the exceptional claims ever be confirmed and widely accepted that would amount to a rejection of Darwinism, though not, crucially, of the more encompassing idea of evolution (so creationists need not rejoice).

Now, cultural evolution is directed not just in outcome, which would be compatible with a Darwinian explanation, but also at the source. We direct it by consciously focusing on one problem or another, deciding to work on one solution or another. I am not, obviously, suggesting that all human cognition is conscious, we know better by now. But even if a relatively small fraction is (i.e., unless you belong to the “it’s all an illusion” school of non-conscious thought) then cultural evolution departs in a major way from its biological equivalent.

The second objection to a Darwinian model of cultural evolution raised (and quickly dismissed) by Buskes is connected to the dreaded L-word. Lamarckism is a really, really bad word in evolutionary circles, arguably undeservedly so. Lamarck, after all, was a pioneer of the field, one of the first modern thinkers to explore the idea of a naturalistic explanation for the history and complexity of the biological world. Yes, he got major details wrong, but that’s the way science works and makes progress. Moreover, let’s not forget that Darwin himself — who died without figuring out a mechanism to account for the origin of biological variation so crucial to his theory — flirted with Lamarckism and tried to incorporate it into his own view of biology. (Mendel, a contemporary of Darwin, had figured it out, but Darwin never read Mendel’s paper, even though he apparently received a reprint of it.)

It isn’t even clear, really, what Lamarck actually said. I have never read the original text (and, I guarantee you, neither have the overwhelming majority of people who have no qualms pontificating about it), but I understand that his famous notion of the inheritance of acquired characteristics — because of which the L-word has enduring negative connotations — was a relatively minor part of his overall theory.

Indeed, the major component of Lamarckism, according to my colleague Eva Jablonka, who has thought a lot about this stuff (and has read Lamarck!), was the idea that organisms react actively to environmental challenges, as opposed to the more “passive” process of natural selection postulated by Darwin. So, really, the chief Lamarckian idea has more to do with directedness, the topic we discussed above, than with the inheritance of acquired characteristics.

Nonetheless, the latter is there too, and it applies beautifully to cultural evolution. As Buskes himself readily acknowledges, biological evolution works (mostly, there are exceptions, especially but not only in the bacterial world) by way of vertical transmission of information, from the parental to the offspring generations. Cultural evolution does incorporate vertical transmission (you can and should teach stuff to your kids!), but also rampant horizontal transmission (peer-to-peer, so to speak), and even “oblique” transmission (as in from a teacher who belongs to the previous generation to students who belong to the next one).

To recap then, take a look at the figure below, which summarizes what I think are the differences between biological (Darwinian) and cultural (Lamarckian) evolution:

I think the divergence between the two is clear enough. Of course, we are still talking about evolution, and not just in the sense of “change over time” (as in the evolution of the universe, for instance). This is cumulative evolution that brings about complexification and adaptedness (though plenty of both biological and cultural structures/artifacts are not at all “adaptive,” and of course the fitness currency is much more clear in the case of biological evolution than in the cultural instance — there is quite a bit more work to do here!).

The conclusion that biological and cultural evolution are different also nicely accounts for the fact that cultural evolution is so much more dynamic (it happens much faster) and unpredictable than its biological counterpart. If we think of both as instances of Darwinism that difference becomes more puzzling.

All of the above said, we already know that Darwinian evolution is not confined to biological systems: computer programmers have worked with “genetic algorithms” for a long time now, in the process independently rediscovering many of the basic ideas of (biological) population genetic theory. At the moment, though, we don’t have any example of Lamarckian evolution outside of humanity. If we ever succeed in producing truly artificial intelligence, that would likely count as a second example on this planet (other than our own), and of course it may be that there are many other cultures scattered throughout the universe. Hopefully, we shall see about that at some point in our future.



This work is distributed with Creative Commons license Attribution - Non commercial 3.0 Unported.

Alva Noë - You Say 'Tomato'

Another cool post from Alva Noë at NPR's 13.7 Cosmos and Culture blog - a fun look at variation in the development of language.

You Say 'Tomato'

January 21, 2011

by Alva Noë

My dad speaks with a German accent. Or so I am told. I can't hear it. Nothing unusual about that. But this is an instance of a very important, yet poorly understand, human phenomenon: the Variation Effect (as I'll call it).

To bring the Variation Effect into focus, consider some examples:

How does one pronounce the word "thursday?" Well, they do it one way in London's cockney East End, and a different way in afro-caribbean Brixton. Different pronunciations abound in Brisbane, Brooklyn, Ashville, and British Columbia. There is no one way to say "thursday," or any other word for that matter.

Variety occurs not only at the level of regions and populations. The next time you are at a table with friends, or sitting at a bar, or in a shop, pay attention to the way people talk. You'll notice surprising variation in inflection, emphasis, contraction, rhythm, melody, volume, timbre, etc.

In fact, it's variation all the way down, even at the level of the individual. You choose your words and articulate your speech one way when you're talking to an elderly man in the nursing home, and another way when you're addressing students from the podium, or when you're discussing the quarterback's performance with other fans at the stadium. What counts as stylish, thoughtful, polite, sensitive, respectful, funny, generous varies from one setting to another, depending on, among other things, to whom you are talking, whether the conversation is professional, and so on. It is mark either of stupidity or arrogance to be unable or unwilling to accommodate one's manner of speech to the circumstances in which one finds oneself.

As variation plays a central role in biological evolution, it also plays a fascinating role in the evolution of languages, as Guy Deutscher tells in his delightful book The Unfolding of Language.

Consider: The French say pied, whereas we say foot. They say pere, where we say father. To our for, they have pour, and where we say first, they say premier. Systematically there is a correspondence between words with p sounds in French and words with f sounds in English. What explains this, say historians of language, is that the French and English languages descend from a common ancestor. For various reasons the French, but not the English, preserves the more ancient p-sound pronunciations that would have been used in this ancestral tongue. At some point in the last four hundred years or so, speakers of languages such as English, German and Danish, but not speakers of French, Italian and Spanish, started to say f whereas earlier we said p.

How did this transition from happen? What's remarkable is that the change goes unmentioned in the historical record. How can this be? First, how can people have failed to notice and remark on a steady systematic change in the way people talk? And second, how could they have failed to shut it down. Speakers love to criticize mispronunciation, and surely that's what saying f for would have sounded like, a big error!

One hypothesis is that the change was imperceptible because it was gradual. As Deutscher explains, leading linguists as recently as the middle of the last century thought this gradual-change thesis was plausible. But it isn't. It's ludicrous. As Deutscher remarks, there's p, there's pf, and there's f. How is gradual change supposed to mask those contrasts? You can hear the difference, can't you?

Some ideas are beautiful and the explanation Deutscher offers is a very beautiful indeed. The very question — why didn't people notice the sound change when it happened? — relies on the tacit assumption that there was ever a single way people pronounced the words in question. But there is no one way to pronounce these words or any other. The ground of linguistic reality is comprehensible variation. And so there never was a single or unified sound change.

Then what happened? All there is and ever was is variation, but what does change, over time, is the frequency of different forms or pronunciations across the field of variations. People didn't change the way they talked. What changed was the number of people who talked one way relative to those who talked another.

And this explains why we didn't notice the sound change. This is an example of the Variation Effect. We have great facility adapting to, accommodating and ignoring variation.

Did you notice when "bad," in the mouths of certain speakers, starting meaning "good," or, to go back in time, when "cool" started to mean stylish and positive? I hear my student describe a book as sweet and I know he means something very different from what my mother would mean if she were to describe the very same book as sweet. We are fluent and adaptable when it comes to different ways of talking here and now, and so, with all the more reason, we are not nonplussed by changes in the frequency distribution of different ways of talking. Meaning changes are not one-off occurrences, like heart attacks. They are gradual shifts in the behavior of lots of people against a background of unceasing variation.

Or consider a visual example: What does this tomato look like? Well, it looks one way from up close, when I hold it in my hand. It looks entirely differently when I look at it from across the room, or when it is sitting on a pile of two hundred tomatoes in the grocery store. And so likewise, its color looks one way under the store's fluorescent overheads and entirely differently in day light, or in the yellow tungsten lighting in the kitchen at home.

How does it really look? There's no such thing.

The point is not that the tomato isn't really red, or that there isn't in fact a single word thursday. It's that to perceive entities or properties such as these is to be knowledgeably or skillfully sensitive to patterns or stuctures of variation — to the ways how things look, or how words sound, predictably changes as circumstances change.

To perceive a word is to perceive something that is, of its basic nature, open to varieties of ways of showing up. A word that could only be pronounced one way (by one person? on a single occasion?) would not be a word at all. And to perceive a colored object is to understand — practically, not intellectually — that how it looks would vary in reliable ways were the lighting, or one's angle of viewing, to change. That's just what it is to have a certain color. It's to be a locus of possible visual variation of a certain style.

To perceive or cognize the world at all is to be sensitive the way patterns of variation allow for invariance to show up for us. We achieve access to that which is invariant (the color, the word) not because we are blind to variation, but because we are so fluent in our mastery of variation that we can let it recede for us and rest in the background.

And this fluent mastery of ever-present variation — the Variation Effect — is the hallmark of understanding.

Tags: language, evolution, variation, diversity, Alva Noë, You Say 'Tomato', NPR, 13.7 Cosmos and Culture, neuroscience, Guy Deutscher, The Unfolding of Language