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April 26, 2003


Thanks again to everyone who welcomed my introductory blog.

I am planning to post a series of notes discussing various issues of cultural
evolution, altruism, group selection, and so on. Here is the first. I hope this will provoke both critical and constructive comments, including references to empirical and theoretical studies I have overlooked.

Analogies are often drawn between biological evolution and ‘social’ or ‘cultural’ evolution. I believe these analogies are seldom enlightening, and often misleading. There are too many major differences between culture and biology for the analogies to be useful. Notably:

1. In biological heredity an individual has a well-defined set of ‘ancestors’. Coefficients of relationship can be calculated, and genetic regressions and correlations estimated. In contrast, cultural traits can be transmitted between any number of biologically unrelated individuals - even (by means of writing and other media) between people widely separated in time and space.

2. With unimportant exceptions, biological heredity cannot transmit traits acquired during the lifetime of the individual, whereas cultural transmission frequently does.

3. The processes leading to variation in biological heredity - mutation, recombination, meiosis, etc - are unconscious and random, in the sense that they have no tendency to serve any ‘purpose’. (I am ignoring the possibilities of eugenics, artificial selection, genetic engineering, etc.) In contrast, cultural change and innovation are often conscious and aimed at achieving a goal. There appears to be nothing in cultural transmission closely analogous to the ‘randomising’ features of biological heredity, which are important for biological evolution. (I’m aware that in some areas, such as linguistics, attempts have been made to estimate the amount of ‘transmission error’, but this remains a vague and limited analogy to biological mutation.)

4. Individuals have no choice in receiving their biological inheritance, whereas people frequently do have a choice in deciding whether to accept some cultural trait.

5. In biology there is a distinction between the genotype, which contains inherited information, and the phenotype, which is the set of observable traits of the individual, and is not directly inherited. The genotype forms the basis for development of the phenotype, which varies according to ‘nurture’, but has a predictable correlation with the genotype. The phenotype can to some extent be changed by deliberate choice, whereas the genotype cannot (again, ignoring genetic engineering, etc.) By contrast, in culture it is not clear that the genotype-phenotype distinction is applicable at all. Ultimately, cultural behaviour must have some genetic basis, but this may be of a general, species-wide kind. The specific form taken by the culture of a society is only very loosely constrained, if at all, by the genetic basis, as cultural traits can be abandoned or modified almost without limit during the lifetime of an individual.

6. Cultural traits are often specific to certain ethnic or social groups. Because of this it is often argued (or assumed) that in cultural evolution the group, rather than the individual, is the unit of evolution by natural selection. This would entail that groups have a life-cycle of birth, reproduction, and death. But groups do not literally die (except in the rare case of total extinction), and they do not literally reproduce themselves. Also, unlike biological individuals, they may split, reunite, or merge with other groups.

7. In biology, most organisms have the capacity to produce many offspring, and there is considerable variance in reproductive success. This is a prerequisite for natural selection to operate. In culture, by contrast, even if social groups may sometimes in a loose sense reproduce (e.g. by forming colonies), the rate of ‘reproduction’ is very low, and has little variance. For example, there are nearly 200 recognised independent countries in the world, but it is doubtful if any of them can be said to have ‘reproduced’ during the last century (unless you count the breakup of the USSR and Yugoslavia as ‘reproduction’). Yet there has been immense cultural change in all of those countries during that period.

8. Even when social groups give rise to ‘offspring’ in the form of colonies or emigrant communities, these seldom closely resemble the ‘parents’; e.g. Singapore is formed mainly by people of Chinese origin, but in many respects it is different from China.

9. Biological individuals compete with each other for available resources, and genes compete with each other for possession of genetic ‘loci’. There is nothing closely analogous to this in cultural evolution. It is true that some cultural traits are incompatible with others - you cannot be a Muslim and a Roman Catholic - but this is probably the exception rather than the rule. It is therefore doubtful whether there is a ‘struggle for existence’ among most cultural traits.

10. Biological traits are usually adaptive for the individuals who possess them, in the sense that possession of the trait enhances their reproductive fitness. Genes producing traits that impair reproductive fitness will be eliminated by natural selection. In contrast, there is no reason to suppose that cultural traits (with some important exceptions, such as economic competition in a free market) are usually beneficial in any sense to the individuals or groups that possess them. (As this goes against a lot of sociological and anthropological dogma, I may come back to it in another note.) It is true that people usually believe that their customs (witchcraft, circumcision, sacrificing the first-born, etc) are beneficial, but people hold a lot of false beliefs.

I conclude that the differences between biological and cultural evolution are so great that analogies between them are usually worthless. In particular, I do not believe that cultural traits have been produced by any process closely resembling natural selection.

But I am ‘blogged out’ for now, and will return to this subject again.


Posted by David B at 11:15 AM

[Shat. Meant to post this edited comment below. universal law: when posting on the internet: something always feks up]

David, two excellent posts, I've enjoyed reading them and am commenting because I'm disappointed that the other gaggle of posters are refraining -- not because my comments might hold more pertinence.

It seems that phenotypical [if I'm using this word I learned here at Gene Expression correctly] evolution, from a scientific perspective, is what separates man from the other animals to greatest extent; with our capacity for memory storage through the evolution of language and the process of storing that information phenotypically. Through this process we accelerate adaptation past the genetic process that we inherit with the other animals; and from our perspective, they appear to rely upon for the most part: genetic evolution.

It is good conjecture on your part to provoke the dissimilarity between the two -- to make issue with that, their seems no reason for why, the two processes should not be similar. Isolating two phenomenon, and positing that they are distinct and not related seems useful for discernment initially, yet, broadly recognized, it would seem that a similarity in process would be more likely.

Through memory storage and the reinterpretation of our senses via induction & deduction we utilize our expanding languages (maybe algorithms) to discern ever-expanding patterns; that are maybe provoked by a universal force of one of the elements of nature, electricity for example, seeking the path of least resistance. Its like we've climbed inside the eon-like slow process of evolution via adaptation -- and revved it up! I can't see any reason why these processes should be all that dissimilar.

Sorry for the broad scope and arm-chair analysis via making sweeping conjecture without the heavy lifting of scientific dot-connecting. . . I'm waiting for some other commentators to get in here.

Posted by: reader at April 27, 2003 05:50 AM

Perhaps one could draw an analogy between cultural evolution and evolution in bacteria: Bacteria swap bits of genetic information with other bacterial species, like ideas flowing between cultures. Successful (or temporarily lucky) bacteria reproduce by fission, so the effective evolutionary unit is a clone of genetically identical bacteria - it can grow, shrink, or fission, much like cultures. A really successful clone will spread all over, with minor genetic variations due to transcription errors and to gene-swapping, but maintaining the characteristics that made it successful - much like western cultures spread out from Europe. Less successful clones either die out or manage to acquire the key genes - and many, many human cultures have died out totally, while the survivors have been those able to learn and use foreign ideas when necessary.

Posted by: markm at April 27, 2003 10:10 AM

One quibble. Contra point 7 it could be said that British Parliamentary government has "reproduced" given that Canada and Australia, at least, are scions of that tradition. Similarly, there are quite a few Republics around.

Posted by: John Purdy at April 27, 2003 06:41 PM

Thanks. All good comments. I won't reply in detail now, but will take account of comments in further posts.

Posted by: David Burbridge at April 29, 2003 02:55 AM