Sunday, 13 August 2017

Mutations and recombination in cultural evolution

Another claim in the recent Creanzaa, Kolodny and Feldman document (Cultural evolutionary theory: How culture evolves and why it matters) is my topic today. They say:

Unlike in genetics, where mutations are the source of new traits, cultural innovations can occur via multiple processes and at multiple scales
To start with, this is rather obviously not true: classically, mutations and recombination are the source of new traits in evolutionary theory. However, are the authors correct to claim that these processes need augmenting in cultural evolution? The answer, I think is: not if you conceive of them properly in the first place. Let me explain.

To start with, let's look at what the authors claim are the new processes that go beyond mutation in the cultural domain. They give two examples. One is individual trial-and-error learning. They also say that:

New cultural traits can also originate when existing traits are combined in novel ways
This is cultural recombination - the parallel in cultural evolution of recombination in the organic realm. Do the authors really not know that ideas have sex too?

What about trial-and-error learning, though? Surely there is no leaning in genetics. Trial-and-error learning is a composite process. It starts with trials, which are often mutations of previous trials. Then there is the "error" part, which does not involve generating new variation at all, but rather is based on discarding information based on its success. In other words, it is selection, not mutation or recombination. By breaking trial-and-error learning down into its component parts, it is found to be a composite product of mutation, recombination and selection - not some entirely new process demanding fundamental additions to evolutionary theory. Skinner realised this, by formulating his learning theory while using evolutionary terminology (such as "extinction"). Many others have followed in his footsteps, conceiving of learning in evolutionary terms.

Isn't this a matter of terminology? With these author's definition of 'mutation' they are right, but with my definition of 'mutation', I am right? Yes, but terminology isn't a case of words meaning whatever you want them to mean. Scientific terminology should carve nature at the joints. Definitions of 'mutation' and 'recombination' that apply equally to both organic and cultural evolution are useful, I submit. Less general ones are not so useful.

To summarize, it is possible to conceive of mutation and recombination in a way that make them encompass all sources of variation. Mutations are sources of variation based on one piece of inherited information. Recombination is a source of variation based on two-or-more pieces of inherited information. In theory, it might appear that there's one other possible process: creation - variation based in inherited inforation which comes out of nowhere. One might give the origin of life as an example of genes arising from non-genes. However, we don't really need this proposed 'creation' process. Information never really comes out of nowhere. There's a law of conservation of information - parallel to the laws of conservation of energy and conservation of charge. We can see this in the microsopic reversibility of physics - information is neither created nor destroyed.

I claim then, that mutation and recombination have it covered. The additions to evolutionary theory proposed by these authors are not necessary. They are unnecessaary complications, which evolutionary biologists should soundly reject as not contributing anything to the basic theory.

Saturday, 12 August 2017

Diagram showing where cultural evolution in academia goes wrong

Creanzaa, Kolodny and Feldman have a recent document out titled: Cultural evolutionary theory: How culture evolves and why it matters. It has a nice diagram which is useful in illustrating where academia goes wrong in its study of cultural evolution. Here is the diagram:

The caption reads: "Cultural transmission is more complex than genetic transmission and may occur on short timescales, even within a single generation."

This diagram is profoundly misleading. It is based on a view of cultural evolution that doesn't include symbiology. A genes vs culture diagram that includes cultural symbionts on one side, but not genetic symbionts on the other is not showing the whole picture. Humans share DNA between individuals - in the form of bacteria, viruses, yeasts, fruits and vegetables - very much as they share culture between individuals.

Framing the diagram as "Human genes" vs "Human culture" is not comparing like with like. Bacterial and viral genes are not part of the human genome (unless you count the 10% of the human genome that is descended from viral genomes) - but human culture isn't part of it either. On the left, symbionts are excluded, while on the right they are included. It is an unfair comparison which leads to the confusion propagated by the caption. In fact parasite evolution can happen within a single host generation in both the cultural and organic realms. Contrary to the spirit of the diagram you can get genes from peers in both cultural and organic evolution. They are parasite genes, or symbiont genes in both cases. Cultural evolution does not differ from organic evolution in this respect. The idea that in culture you can get genes from many sources, while in organic evolution you only get them from your parents is a popular misconception about the topic.

The whole document has a whole section on "Culture and Microbes". However there is no mention of the idea that culture behaves similarly to microbes and other symbionts. The man-machne symbiosis, for example is not mentioned. Yet symbiosis is the very basis of the whole field according to memetics, one of the very few symbiosis-aware treatments of cultural evolution out there.

The neglect of symbiology in academic cultural evolution mirrors its neglect in the study of organic evolution - until the 1960s. However, cultural evolution's scientific lag means that cultural evolution is far behind, and few academics have even a basic understanding the relevance of symbiosis to the evolution of culture. Maybe these folk never read Cloak (1975) and Dawkins (1976).

I think the history of this misconception of the whole field in academia is fascinating. Why has it lasted for so long and why has it not yet been corrected? I don't have all the answers but I think the origin is fairly clear. Anthropologists wanted a complex theory of cultural evolution, to signal their skills to other academics and prospective students. They may also have wanted to distance themselves from previous attempts to marry evolution and culture. Any mention of biology turns most anthropologists off. Artificially weakening the influence of biology in the theory may have made the theory more palatable to other anthropologists. Still, science is a self-correcting enterprise. Eventually, the truth will out.

Friday, 4 August 2017

The tautology criticism yet again

It's frustrating:: critics keep repeating the same long-debunked objections to memetics. Jerry Coyne is one of the latest to raise the objection that memetics is an empty tautology:

“Memetics” is a weak analogy to natural selection that adds nothing except tautology to our view of how human culture evolves. Memetics boils down to this: memes spread because they have properties that allow them to spread.
As any scientific historian will tell you, Darwin's theory faced exactly the same bogus criticism. Critics argued that "survival of the fittest" was a tautology because fitness was defined in terms of who survived. Any evolutionist should be able to explain what is wrong with that argument: "fitness" can be taken to refer to "expected fitness" - as opposed to fitness measured after the fact. Then it isn't a tautology any more.

The exact same reply works for cultural evolution: to make testable predictions, use expected fitnesses.

I have seen much the same objection raised to the Price equation and Hamilton's rule. These have been criticised as tautologies by Martin Nowak and Edward Wilson among others. This criticism ought to be dead these days, but like a zombie, it refuses to lie down.