Daniel Dennett: Darwin, Quasi-Darwianian, Pseudo-Darwinian phenomena in Cultural Evolution?
The blurb reads:
To what extent—if at all—is cultural evolution governed by "Darwinian" algorithms of natural selection? I have been a champion of the "meme's eye" perspective on culture for several decades, and encountered huge resistance, most of it hysterical and confused, but with some serious exceptions. Work by Boyd and Richerson, Pagel, Sperber, Laland and others provides valuable alternative perspectives, and perhaps the time is right for a taxonomy of sorts. Peter Godfrey Smith's recent book, Darwinian Populations and Natural Selection, provides a useful thinking tool: a multi-dimensional "Darwinian Space" in which phenomena can be located. He neglects to apply this tool to cultural evolution, which is a task I am now embarking on. (See the brief discussion in "Homunculi Rule," my commentary on Godfrey Smith's book.) This will be an introduction to the questions and a request for help from those at SFI who are more adept model-mongers than I am.
Autocatalysis: potentially autocatalytic mode of generation.
Similarity: potentially above-chance similarity between parent and offspring.
Informational: ability to pass on information to offspring. This is a requirement for
informational replicators.
Inclusivity: The widest definition has to include genes, memes, and possibly other entities
as well.
Specificity: The definition must be able to distinguish between various multiplying
entities: genes, memes, simple chemical cycle intermediates, lipid vesicles, kinetic
multipliers, organisms, and higher-level entities in a clear and exact way.
The document asks:
What is the qualitative and quantitative difference between genes, organisms, general
autocatalytic intermediates and other multiplying entities?
What are the basic concepts behind the Mullerian criteria multiplication, heredity, and
variability, and what part do they play in replication?
What is replicator identity and similarity? When do we say that two replicators are
identical?
What is common and distinctive of genes and memes? What is the definition that puts
memes and genes into the same box but not organisms?
On reflection, I don't think Universal Darwinism really needs this concept. It can do very
well using the concepts of heredity, copying and reproduction. Distinguishing between the
reproduction of organisms and the reproduction of DNA molecules just isn't a particularly
urgent or important task. This is a good thing - since there's no hard line to be drawn
between them.
Attempts to distinguish replicators from organisms seem to have mostly led to anti-group-selection
rhetoric that claims that groups don't replicate - aren't "units of selection" and so
can't be the beneficiaries of adaptations. Alas, these arguments aren't worth too much.
Laor and Jablonka devote much of their review of Mesoudi's "Cultural Evolution" book
to a call for development and systems theory. Many of their points read like criticisms of memetics.
While I have some differences from Mesoudi, compared to Laor and Jablonka, Mesoudi and I are very much
singing from the same hymn sheet. So, a few replies. Laor and Jablonka ask?
Like cultural behaviors, institutions such as hospitals or churches, are not included in Mesoudi'sdefinition of culture. He suggests that they, like behaviors, are the “phenotypes” of a “cultural genotype” stored in people's brains as neural networks (for example, 3, 213). But since the neural network is a product of social learning that occurs during human development, in what sense is it a genotype? Are “phenotypes” and “genotypes” embodied within an individual or distributed among members of a collective? It seems to us that adherence to notions of genotype and phenotype in the cultural realm, where heredity is an aspect of development and requires an active process of reconstruction, is misplaced (it is, in fact, in need of qualification even in the biological realm!).
There's a neat resolution of this issue: genotypes are composed of heritable information, phenotypes are the things that are influenced by them. This idea applies equally to DNA genes and to memes. The concepts often imply the notion of an individual - and so we have to say what a cultural individual is - but that isn't an insurmountable problem.
As Mesoudi confesses, his outline of a cultural-evolution synthesis inherits the problems of the twentieth century MS, in that it lacks a developmental perspective. We agree with Mesoudi that what development means in the cultural multi-generational context is not entirely clear. However, Jablonka and Lamb have argued that this lack of clarity is part of the solution, not the problem: it is inherent in the fact that the notions of heredity and development in the cultural realm are far less distinct than they are in the biological case.
Genetics and memetics don't involve the study of development. Development is treated by these theories as a black box - containing
arbitrary transformations which map from genotypes to phenotypes. Certainly development influences evolutionary trajectories. However, meteorite strikes, earthquakes, and fashion also influence evolutionary trajectories - we can't include everything under the umbrella of evolutionary theory. Development is a pretty different subject. Yes, there's evolutionary ontology, which applies evolutionary concepts to development - but it is OK to study development separately. As for the supposed "lack of clarity", the concept of "development" is best taken to refer to mappings from genotypes to phenotypes. It applies equally well to the organic and cultural realms. Maybe there's disagreement about the topic, but it seems easy enough to make it into a clear concept.
We believe that the major difference between the approach promoted by Mesoudi and that adopted by most social scientists is that the latter treat culture as a system. Cultural systems are not super-organisms, but they are also not an assembly of individuals, institutions and traits. They are – to differing extents and in different levels and ways – functionally integrated entities, and they occupy a middle-ground between a super-organism and an aggregate, a locus that is difficult to conceptualize if one is wedded to a traditional population-genetics-based metaphor. Social scientists endorsing the systems view do not reject approaches that focus on distinct and isolatable elements of culture, but they do treat the results of such analyses with caution, regarding them as limited and preliminary forays into the analysis of culture.
There are two issues here. The first is that cultures are, overwhelmingly, assemblies of individuals, institutions and traits. Analysis of culture in those terms is highly productive. Entire cultures don't have intelligent designers making them. They are cobbled together by cultural evolution. Analysing culture in terms of its parts follows the scientific practice of reductionism, of breaking down a complex whole into its component parts in order to understand it. This has been a tremendously productive approach in practically all branches of science. However, the application of frequency analysis - and other such techniques - to cultural variation doesn't presuppose the lack of high-level system characters. Their existence, or rather in most cases their lack of existence, is a separate empirical issue.
Alan wrote something odd about memes in a recent paper. He wrote that we should not expect to find "well-designed cultural phenotypes".
Here's what he wrote:
Third, the foregoing discussion of the importance of uniformity of relatedness across loci raises a question about memes. In the genetic theory, the number of offspring is the same for all loci (assuming that they all have the same pattern of inheritance), and it is in relatedness, once social behaviour is considered, that we saw the possibility of discordance. But with cultural inheritance, the number of offspring will be different for each culturgen, and we should therefore not expect to find well-designed cultural phenotypes.
However, it seems pretty obvious that we do see some pretty "well-designed cultural phenotypes". The memes that make up (say)
Linux might not have quite the harmony of those that make up an elephant - but the level of functional design is not really
obviously lower.
Also, there are things like books - what are created by a single author. Yes, the underlying memes may be fighting for survival,
but they still get vetted by a human designer, in the process of making a designed whole. I think the supposed lack of well-designed cultural phenotypes is being exaggerated by Alan here.
The place where we do see conflict is between all the memes inside an individual human. However, refering to all the memes inside an individual human as a "cultural phenotype" is the fallacy of the inclusive phenotype. That's what you often get if you approach cultural evolution without a proper understanding of symbiology. I hope that Alan wasn't going there.
I favour using inclusive fitness - in place of individual fitness - in most places where the concept is used. Individual fitness just isn't nature's maximand.
One thing this means is that kin selection gets classified as a form of genetic self-interest - rather than
being classified as being "altruism". "Reciprocal altruism" is also classified as being selfish - despite its name.
However, others argue against such definitions, saying things like this:
As Sober and Wilson (1998) note, if one insists on saying that behaviours which evolve by kin selection / donor-recipient correlation are ‘really selfish’, one ends up reserving the word ‘altruistic’ for behaviours which cannot evolve by natural selection at all.
If an altruistic behavior reduces the net fitness of the altruist and his kin, it cannot evolve.
The problem with these objections is that they are trivially wrong. Altruistic behaviours
can be favoured by natural selection - even if they are deleterious to those displaying them.
This is a simple consequence of the "extended phenotype" perspective - that traits may be coded
for in different organisms from those that exhibit them.
Viruses cause all kinds of deleterious behavioural traits in their hosts - coughing, sneezing, itching, suicide, etc.
However, these deleterious behaviours evidently do evolve via natural selection.
In the case of altruism, one of the the most likely cases involves manipulation of hosts by memes causing altruism:
Memes like to cause positive interactions between their hosts - since such friendly contact is one of the main
ways they use to spread between their hosts. So, making their hosts eager to help each other can be expected to
be the type of trait which many memes encourage. Such interactions may not necessarily be beneficial to
their hosts (altruism is, by definition, a costly act). However, such behaviour most definitely can
still evolve - via natural selection acting on memes.
I think that part of the reason we still see these kinds of explanations being offered is that understanding of memetics is
not yet very widespread.
This is a 23 minute video on "universal Darwinism and the meaning of life". The video features a pretty youthful narrator - and seems a little amateurish. It seems to have a lot of physics, cosmology and philosophy in it. There's some speculations about evolutionary ethics, but otherwise only rather limited evolution-related content.
Universal Darwinism represents a powerful theory of the evolution of dynamic systems.
It spans between the inorganic and organic realms, covering a wide range of processes.
However, it faces some competition. In particular
maximum entropy thermodynamicsalso purports to explain essentially the same range of phenomena.
This leads to the question of what the relationship between these ideas is - and whether we
really need both of them.
Since maximum entropy thermodynamics and the maximum entropy principle are still little known about
and poorly understood, I should probably start by explaining what these ideas are all about.
However, a proper summary would probably take a while. So very briefly, here, we'll be using
maximum entropy to refer to the idea that maximizing entropy explains many of the irreversible
dynamics seen in the universe. In other words, the world behaves so as to maximize entropy.
Maximum entropy is quite different from the second law of thermodynamics. The second law of
thermodynamics says that entropy rarely decreases. Maximum entropy says that entropy is maximized.
Those are very different ideas. Maximum entropy constrains expectations a lot more than
the second law does.
Here's an essay of mine about maximum entropy.
Here's another one by the wonderful science writer, John Whitfield.
It is clear that Universal Darwinism and maximum entropy thermodynamics are very similar. Maximum entropy thermodynamics represents a good thermodynamic characterization of universal Darwinism.
The two ideas evidently have a massive overlap in their domains of application and the predictions they make.
Their similarity is surprising if you look at the contents of the two theories. They seem to have
quite different structures. However, it was observed by Lotka back in 1922 that the maximum entropy
applies to living systems. Since then we have developed an understanding of why that is so:
organisms compete to reach sources of order first. Organisms need order to fuel their living processes.
They also try and keep such sources of order away from competitors, sometimes even if that involves destroying those resources.
Universal Darwinism scores some points over maximum entropy thermodynamics in cases of sophisticated systems. The somewhat distinct goals of complex living systems can be usefully understood as products of low level entropy maximization via the idea of goal delegation.
Both ideas apply to irreversible systems. Reversible dynamics lead to no change in entropy. Similarly, in universal Darwinism, mutation and selection means that something has to die or be lost. I am not talking about microscopic reversibility here, but macroscopic reversibility - i.e. Humpty Dumpty.
I think that the literature in each of these two fields should substantially enrich the other.
Rather than competing, I hope that they will complement each other.
However, both ideas are currently surrounded by much confusion and controversy. Neither is popular or well established. I hope that their union will prove to be a constructive one.
The idea of within-brain evolution of ideas highlights the aptness
of the virus/parasite/microbe comparisons often used in memetics.
In organic evolution, many microbes spend most of their time evolving within their hosts, only
occasionally bursting forth in an attempt to spread between them. Sometimes they lie
dormant for extended periods - in an attempt to evade the host's immune system.
Similarly, much memetic evolution actually takes place within the minds of human hosts.
Ideas sometimes grow, develop and fester within their hosts for months or years before
entering into a transmission phase.
Like many parasites, memes often face alternating selective environments. They need one set
of adaptations to survive within their hosts and another set of adaptations to spread
between them. The results are often a compromise.
Also, like many parasites inside their hosts, memes within minds are often surrounded by their kin -
often their close kin. For example, each time you hum a catch song, more very-similar memory traces
are laid down, reinforcing the memory of the tune. As with organic parasites, the kin-related dynamics
associated with within-brain evolution can be strong.
Human cultural innovations are quite different from the blind mutation and
recombination that supply the raw material for bona fide natural selection. I'm happy
to concede that this is a difference in degree. Sure, natural selection does not
require blind mutation; it can add value to intelligently designed or directed variants.
And sure, the brainchild of a single innovator generally must be tinkered with and combined
with other innovator's brainchildren through social networks before it is of any use.
But what a difference in degree! Genetic mutations and recombinations are strictly
typographical, twiddling the As, Cs, Ts, and Gs with no foreknowledge of their
effects on the organism's interactions with the world.
I think the "difference in degree" business counts as progress. However, this is mostly the same mistakes that Pinker was making in 1997 all over again. This illustrates the power of heritage constraint in Pinker's thinking.
To start with, human cultural innovations are best compared with organic adaptations. Knives with claws, jackets with fur, sonar with echolocation, etc. Comparing cultural innovations with mutation and recombination unfairly misses out the roles of development and selection in the origins of organic innovation. Pinker finds that his own comparison doesn't make much sense - but that's because he's making a rather silly comparison. If the intention was to describe the memetic forces of mutation and recombination (excluding selection and development), you can't use the term "human cultural innovations" to describe these - it is just too misleading.
The other point is that the idea that organic recombination doesn't involve foreknowledge kind-of misses the point of sexual selection. Perhaps strictly there's no such thing as foreknowledge - for genes or memes - but what we do have is prediction, and both genetic and memetic evolution make use of it.
When an organism chooses a mate, they are deciding who to recombine their genes with.
This decision is not too "typographical" - it involves creating a complex world model and
evaluating the expected consequences of various mate choices. So: recombination of memes
isn't pure "typographical twiddling", but neither is recombination of genes. Both genetic and memetic recombination can involve learning, experimentation - and other phenomena associated with complex cognition. It just isn't true that prediction of expected results and complex cognition is involved in cultural recombination and not organic recombination.
This criticism illustrates a common pattern in criticisms of memetics - people complain that genetic evolution and memetic evolution are more different than memetics claims - and it turns out that this isn't because of their views of cultural evolution, but rather because of overly-simplistic views about how organic evolution works.
Pinker closes with:
But unlike the case of genetic evolution, where selection assumes the full burden of generating adaptation from the vast space of genetic possibilities, most of the work done in exploring the space of logically possible ideas must be attributed to the organization of the brain.
We can be more specific than this. The search of possibilities is performed by an algorithm involving copying with variation and selective retention within the brain. Any non-trivial optimization strategy necessarily involves such an evolutionary process. Selection is the "narrowing" force in evolution. Whenever adaptations are generated from a vast space of possibilities, selection is involved. That's just the terminology biologists use to describe such "narrowing" processes. So: it turns out that selection is doing most of the work in generating cultural adaptations too. Pinker claims that selection "assumes the full burden" of generating adaptations in the organic realm, but that's not strictly correct - you need a source of variation to generate organic adaptations too.
Evolutionary ontogeny is formed from the union of evolutionary theory and developmental biology. It covers the evolution of biological organisms during their development. It explains how organisms develop in terms of copying, variation and selection - between cells
or other structures.
Examples of phenomena it explains include: how roots grow around obstacles, how trees seek out holes in the canopy, how brains learn, how the immune systems adapts to pathogens. It helps to explain how organisms develop diverse phenotypes from similar phenotypes - i.e. developmental plasticity.
Since DNA copying fidelity is often high - and organism lifespans are often short - there typically isn't much DNA-evolution involved in evolutionary ontogeny. Instead, position, chemical gradients and other factors evolve during development.
Developmental biology has paid little attention to evolutionary theory to date. However, an evolutionary approach to development seems likely to bring similar benefits to those that it has brought elsewhere in the life sciences.
The field is sometimes called "Evo-Devo" though typically then the only evolution involved is the historical kind.
This isn't completely unreasonable, but it seems more regular to me to classify Darwin's progress by application domain:
Organic evolution;
Cultural evolution;
Psychological evolution;
Developmental evolution;
Physical evolution.
Cultural evolution is what memetics is all about - that's the revolution that's going on now.
Psychological evolution seems to me to be lagging behind cultural evolution. It's the next big domain where Darwinian evolutionary theory will be applied.
Developmental evolution covers psychological evolution, immunological evolution, and other aspects of development.
Physical evolution could be seen as being a synonym for universal Darwinism. It's an umbrella category which includes all evolving phenomena. This seems to have been the area of Darwinism which has proved hardest for people to grasp.
There have been quite a few attempts to imitate the success of the Human Genome project in the realm of memes. The latest is The Human Memome Project. The basic idea seems to be to mirror the impact of genomic analysis on disease, by identifying, categorizing and rating the impact of memes on human health and wellbeing. Here's a video about the project:
There's a new article on memetics by Michael Greenker: Meme’s the Word.
The article is quite upbeat, saying:
The study of memetics also changes the way we think about thinking. All revolutions and paradigm shifts evoke fear and derision, of course, and the resistance from all sides to meme theory demonstrates its potential power. The emerging discipline of memetics will take the humanities and the social sciences by storm, with the potential to be the killer-app of the 21st century.
...and...
The model of memetics will allow researchers to get ahead of this trend and finally come to grips with 21st century global society and all of its potential. Meme theory represents the next step in the intellectual and metaphysical revolution Darwin sparked two and a half centuries ago.
That would certainly be nice, but memetics has faced almost four decades of resistance, through scientific turf wars, stupidity, misrepresentation, misunderstandings, lack of leadership and various other problems. Back when I published my book on Memetics a few years back, I hoped it might help to finally push memetics into the mainstream. However, having the correct framework is only the first stage in a long process.
Darwin's revolution is over 150 years old. Looking at the current situation, it may be a while yet before it is done.
Thumbs up from me for Razib Khan for his recent posts dinging most cultural-anthropology here and here.
Anthropologists have turned into one of the main forces standing between humanity and a proper science of culture.
Also, thumbs up for knowing enough to understand that culture evolves. However, I have to ding Razib for this:
an understanding of evolution or genetics is not necessary to gain a first order understanding of the nature of the phenomenon of human culture, but cognition is
It's just a daft thing to say. I would compare it to saying that evolution or genetics is not necessary for a first order understanding of the nature of animals, but organic chemistry is. That sort of thing isn't very meaningful or helpful.
Culture evolves. That's just as important to understanding culture as it is to understanding animals and plants. The "first order understanding" business is weasel words.
In sexual organisms genetic inheritance is symmetric (the autosomal genome has equal contributions from both parents), and exclusively vertical (parents to offspring). In contrast cultural inheritance can be asymmetric (i.e., one inherits by and large the culture of one parent) and horizontal (one inherits the culture of one’s peers). [...] This regular and systematic inter-quasi-generational horizontal transmission illustrates flexibility of cultural transmission which has few parallels in biological genetics.
Razib is drawing an unhelpful comparision. Memes are not much like autosomal genes, but they are a lot like genes in microbes and parasites.
The claim that horizontal transmission in cultural evolution has few parallels in "biological genetics" seems simply wrong: microbes and viruses are transmitted horizontally between humans whenever they touch each other, breathe in each other's vicinity or eat anything.
The whole "Why culture is chunky and genes are creamy" thesis seems very dubious to me. Razib has picked a trait for which there's little variation (skin colour) and compared it with a cultural trait for which there's a lot of variation (language type). However comparing a cultural trait for which there's little variation (e.g. which side of the road you drive on) with a genetic trait which has a lot of variation (e.g. what skin viruses you have) would have led to the opposite conclusion. All Razib's example shows is that all human DNA has a fairly recent common ancestor, while many cultural traits evolve rapidly and diversify quickly - due to the short generation times of memes. However, that isn't really news and doesn't lead to grand generalizations about the relationship between memes and genes. There are plenty of genes that have short generation times and evolve rapidly too - they just aren't human genes.
Universal Darwinism leads to some ideas about values, goals and optimization targets:
All values are based on copying with variation and selection;
Adaptive evolution results in goal-directed systems.
The basic idea that values and evolution are intimately linked. Values come from evolution, and evolution produces values.
To expand on these ideas:
Copying-with-variation and selection is the basis of all non-trivial optimization processes
Trivial optimization processes include things like random search and exhaustive search which maintain
little or no state between trials.
The basic idea is that all values come from evolving systems. Everyone is familiar with goal-directed behaviour that comes from genes. Much animal behaviour fits into this category. Another source of human goal-directed behaviour is memes. Catholic priests are typically not helping their genes to reproduce, it's memes that they labour for. The third main source of goal-directed behaviour is copied structures within minds - which can result in behaviour that produces pleasure, but is non-adaptive for memes and genes.
Note that the copying need not only consist of previously-successful solutions. Information about failures and mistakes could also be copied.
This is not a new idea - for example here's Evan Louis Sheenan in The Laughing Genes (page 79):
I want to make the point that survival, especially for our replicators, is necessarily at the root of all our oughts.
...and...
Replicator survival is the fundamental principle from which we derive all our oughts, even though it may not seem at all obvious to us.
The second part of the thesis is:
Cumulative evolutionary processes result in goal-directed systems
Cumulative evolution is the opposite of devolution. It's the sort of evolution that results in adaptive complexity - rather than the degeneration and eventual death that results from too-high a mutation rate.
In general, all adaptive evolution encourages variants which act as-though they have the goal of propagating themselves.
These ideas propose an intimate link between value and copying in a wide range of optimization processes. They link morality and ethics, evolutionism, and optimization strategies.
To recap, Dawkins helped to pioneer to the modern theory of cultural
evolution way back in the 1970s, in an early, popular and influential
contribution that pretty-much nailed the topic.
Gould was a know-nothing on the topic of cultural evolution, and produced little but
a
stream of ignorant blather on the topic.
Dawkins coined the term meme, Gould described it as a "meaningless metaphor".
Apologies to readers expecting a battle, but this one is no contest - it seems to me.
I'm feeling a littlemisunderstood by commentators, lately. To recap on a few basics:
Cultural evolution and organic evolution are not exactly the same. Intelligent design, engineering and reverse engineering and multi-parental recombination are new phenomena, facilitating new evolutionary dynamics, much as I explained in A new Kind Of Evolution.
The relationship between organic, cultural and psychological evolution is that they are all instances of a more general Darwinian evolutionary process - based on copying with variation and selection. This idea has now been pointed out by Campbell, Cziko, Durham, Plotkin and many others. Many of the resulting differences in dynamics are due to differences in the information-storage substrates involved. For instance DNA tends to be a serial access medium which it is not easy to write to.
The reason for emphasizing the similarity between cultural and organic evolution here is because so many authors get the relationship wrong by failing to appreciate the depths of the parallels between them. The misunderstandings are numerous. We see them in the writings of Pinker, Gould and many others. I won't name more names here, but:
Some think cultural evolution exhibits horizontal and oblique transmission, while organic evolution
is vertical. This is because they didn't properly consider organic parasites.
Some think that cultural evolution exhibits foresight, while organic evolution is blind. This is often because they didn't properly consider the effect of brains on organic evolution - where mate choice and other effects have allowed intelligence to influence the course of evolution for hundreds of millions of years.
Some think that cultural evolution is directional, while organic evolution is not. This is usually because they failed to appreciate the directionality of organic evolution.
Some think that group selection works in the cultural realm - but not in the organic one. In fact kin selection applies about equally to both domains.
Some think that cultural evolution is Lamarckian, while organic evolution is not. In reality the inheritance of acquired characteristics happens sometimes in both realms (as when a dog inherits its parents' fleas) - as does use-and-disuse (as seen with bulging muscles). However, in both realms, most inheritance is Weismannian - once you properly take within-brain evolution into account. Reverse-engineering of phenotypes does happen in the cultural realm - but is either pretty trivial (as with most imitation) or relatively rare. Also: remember that Darwin was cool with Lamarckian inheritance.
...and so on and so forth, in an apparently endless and misguided quest to preserve the human mind and human culture from the full force of the ravages of Darwinism. Culture evolves, folks. Read the books, the papers - and then get with the program.
Stephen Jay Gould (a more rounded intellectual than Dawkins on these issues) rightly called culture "the Lamarckian juggernaut" because of the pace of change and the ability to adjust, or in the terms of Lamarck "the inheritance of acquired characteristics."
I'm extremely sceptical about the idea that the pace of cultural evolution is fast because it is "Lamarckian". The most obvious hypothesis to account for the speed of cultural evolution being faster than evolution of human DNA is that ideas reproduce rapidly between brains, reproduce rapidly within brains, and are themselves the product of evolving signals in axons and dendrites, which reproduce at a lightning pace. So: incredibly short generation times accounts for most of cultural evolution's rapid pace.
Anyway, I see no easy way forwards on this issue - short of a quantitative analysis. The rapid generation times and high parallelism of evolution inside brains can - in principle - be measured and compared with systems based on DNA - such as viruses and bacteria. I don't expect dramatic differences in evolutionary rates (however measured) per generation in systems with comparable parallelism. Intelligent design mostly speeds up evolution to the extent that it represents a high-speed parallel copying processes with short generation times. I think this is the most obvious null hypothesis for explaining the rate of cultural evolution. It's the baseline from which other hypotheses need to differentiate themselves.
In A Devil's Chaplain wrote that humans (and only humans) have the gift of foresight "something utterly foreign to the blundering short-term ways of natural selection."
Utterly foreign. In the BBC Profiles video while promoting the book he said "The human brain is the only possible engine of departure from Darwinian principles, and it really is."
Dawkins and Dennett (in lecture and interview) both acknowledge that humans "are the only/first intelligent designers on the tree of life." As I have said previously the question is no longer design (which evolution is the answer to) but drive. What are the causal forces that move humans, and their thought around?
The thing is, the human brain itself works on Darwinian principles. Its components use copying ubiquitously (signals are copied whenever an axon branches), and there's variation of what is copied plus selection. Ideas evolve within minds during individual learning, just as they evolve between minds during social learning. Copying, variation and selection are the basic ingredients of Darwinian evolution, according to many formulations of it - so the brain evolves along Darwinian lines.
Within-brain Darwinism was worked out by Campbell, Skinner, Changeux, Edelman, Szathmáry and Calvin - and has been popularized by Cziko, Plotkin, Dennett and myself, among others. In short, the brain is a Darwin machine.
B. F. Skinner was one of those who pioneered this view, making the analogy between Darwinian evolution and learning explicit. He used the term "extinction" to refer to the obliteration of memories - usage that persists in psychology to this day.
No doubt the remaining critics will say that within-brain selection is deliberative selection. However, we have deliberative selection in common-or-garden evolution as well - it's called mate choice, or sexual selection. No doubt critics will say that within-brain variation is composed of directed mutations. However both evolutionary theory and Darwinism are cool with directed mutations. The various definition(s) of "evolution" typically make no mention of the source of variation, they just say that it needs to exist. As for Darwin, he understood relatively little about how variation arose. He had some theories, but largely knew that he didn't know. Directed mutations might well be contrary to neo-Darwinism, but that's a very different ball-game.
Many critics don't have a proper appreciation of the issue of Darwinian evolution within the brain. They think that intelligent design represents a radical departure from evolution. What they don't grasp is that the brain evolves at high speed, and its productions are the result of many generations of reproduction, variation and selection of signals and ideas. Brains are a neat invention, but they still work on evolutionary principles.
Also, for many years, most of the researchers in cultural evolution didn't understand within-brain evolution either. The individual learning folk and the social learning folk came from different disciplines - and it took a while for them to find each other, swap notes and get onto the same page.
A number of other nonselective processes may affect the evolution of ideas. For example, people can learn an idea from others and then innovate, modifying the idea in an effort to improve it. Still other nonselective processes can arise when people synthesize their own beliefs after being exposed to a number of people who behave differently.
Here learning and critical evaluation are described as being "nonselective processes" - when it is now evident that any proper understanding of them would involve considerable quantity of selection between ideas inside minds.
Today, understanding of within-brain evolution lags behind understanding of cultural evolution - which itself remains poorly understood. Universal Darwinism is an even-less-well-understood fourth stage in the evolution revolution.
As for the idea that "humans (and only humans) have the gift of foresight", that is just daft. All animal brains forecast the future consequences of their actions, in order to allow them to choose between them. That's the basis of the memory-prediction framework.
Lastly, it is Darwinian evolution within the brain that represents the primary conceptual link between evolutionary theory and machine intelligence.
References
Calvin, William H. (1987) The brain as a Darwin Machine.
Plotkin, Henry (1994) Darwin Machines and the Nature of Knowledge.
Skinner, B. F. (1953) Science and Human Behavior.
Calvin, William H. (1998) The Cerebral Code: Thinking a Thought in the Mosaics of the Mind.
Edelman, Gerard (1987) Neural Darwinism: The Theory Of Neuronal Group Selection.
Fernando C, Szathmáry E. (2010) Natural selection in the brain. In Toward a theory of thinking (eds B Glatzeder, V Goel, A von Müller), pp. 291–340. Berlin, Germany: Springer.
Fernando, Chrisantha, Goldstein, R. and Szathmáry, Eörs (2010) The Neuronal Replicator Hypothesis. Neural Computation 22 (11): 2809–2857.
While I've long 
Laor and Jablonka devote much of their review of 
Alan wrote something odd about memes in 
I favour using inclusive fitness - in place of individual fitness - in most places where the concept is used. Individual fitness just isn't 
The idea of 
Age-old sceptic about cultural evolution, Steven Pinker
Evolutionary ontogeny is formed from the union of 
In 
There's a new article on memetics by Michael Greenker: 
Thumbs up from me for Razib Khan for his recent posts dinging most cultural-anthropology 
Universal Darwinism leads to some ideas about values, goals and optimization targets:
Someone tried 
I'm feeling a 
From 
A 
Posts
