The phrase ‘Cultural Evolution’ conceals multiple ambiguities that have given rise to considerable conceptual confusion, as workers in this emerging field have attempted to harness various aspects of the explanatory power of evolutionary concepts in the strictly biological realm to account for and model different types of cultural change. Tim Lewens' careful study of the value and limitations of the evolutionary metaphor as a tool for understanding cultural change performs sterling service in disentangling its different variants and subjecting each to a searching critical analysis, leading to a measured and balanced assessment that, while strongly underscoring the very great disanalogies that obtain, both between the dynamics of cultural change and organic evolution and the underlying causal mechanisms that respectively produce them, affords an important and intellectually reputable role for some varieties of ‘evolutionary thinking’ in cultural studies.
The book is very well structured, opening with a perspicuous taxonomy of approaches to the study of cultural change that could be called evolutionary, and identifying some of the key conceptual issues and controversies that arise in connection with each. Following this first chapter, which essentially identifies four, approximately nested, approaches based on successively stronger presumed analogies with organic evolution, subsequent chapters explore these conceptual issues in depth, concluding, in summary, that the least useful attempts to import explanatory insights from biology into the study of culture have been those, such as memetics, which suppose a very strong, even an exact, analogy between the two realms, the most useful being those that take advantage of rather general tools for describing and modelling changes in the distribution of traits, cultural or ‘genetic’, within a population where these traits are passed, in one way or another, between individuals (scare quotes because an underlying theme of the book is that attempts to distinguish rigidly between traits that are genetically inherited and those that are culturally transmitted are less easy to make watertight than might be imagined.)
Lewens identifies three very general ways in which evolutionary ideas might figure in theories of cultural change, which he labels respectively Selectionist, Kinetic and Historical approaches (memetics being a particular case of the Selectionist approach where the analogy with biology is held to be especially close.) Selectionist approaches assume that the primary locus of explanation for cultural change is to be found in some form of natural selection; he observes that one might therefore assume that there must be an analogue in the cultural sphere to the role of DNA, etc., in ensuring accurate replication of cultural traits, but that this is an error; many such theories do not assume the existence of cultural replicators, and those that do - notably memetics – are vulnerable to severe criticism on both conceptual and empirical grounds.
Kinetic approaches do not take natural selection to be centrally important; rather, they concern themselves with the general dynamics of how the distribution of cultural features within a population change over time; though the analogy with biological evolution might here seem very weak, in fact, Lewens argues, considerable explanatory power is afforded to cultural studies from sophisticated mathematical models developed for biology but applicable, because of their generality, to quite a wide variety of cultural contexts. Historical approaches, which are limited to viewing culture as changing over time in a way that can be characterised as evolution in a very broad sense of the term, are included in the taxonomy more for the sake of completeness than because Lewens wants to analyse them in detail – though also because, to the possible consternation of religiously inclined neo-Darwinists, Charles Darwin appears as a paradigmatic exemplar of this approach.
In Chapter Two (rather confusingly titled ‘The Kinetic Theory Of Culture’, since in fact it is largely devoted to a critique of the memetic and more general Selectionist approaches), these general types of approach are treated in reverse order of presumed strength of the analogy with biological evolution, beginning with memetics. A convincing case is made that the spread of ideas, cultural practices and so on through a population does not require, and in many cases does not involve, replication by means of a copying process that is in any way analogous to the action of genes in ensuring the faithful transmission of hereditary characters; there are other ways in which cultural information is passed on, and the attempt to strait-jacket these into a descriptive / explanatory framework borrowed from genetics leads either to error or vacuity.
More general selectionist approaches are treated less severely, but still ultimately rejected as a basis for a comprehensive theory of cultural change. In the absence of clear cultural analogues for concepts as basic to genetics as genotype and phenotype, the notion that cultural items are preserved and modified by natural selection again tends to oscillate between evident falsehood and vacuity. An honourable exception might be made for certain theories regarding the evolution of craft artefacts – here the artefact itself can do duty for the phenotype, while there is typically a highly structured process of training that ensures a high degree of faithfulness in replication, while also allowing for progressive modification in the direction of improved functionality, which might perhaps do duty as an analogue of the genotype. But the very fact that this type of example clearly has quite special features not shared by the majority of cultural phenomena, indicates that the selectionist approach is unlikely to be applicable as a general strategy for understanding cultural change.
By a process of elimination, we are left with the more general ‘Kinetic’ approach as the most fruitful route to understanding cultural change in evolutionary terms. Before returning to a detailed analysis of the virtues and limitations of this approach, Lewens pauses to criticise two common ingredients of cultural evolutionary theories; the notion that ‘Culture is Information’, and the question of the applicability of the idea of ‘Human Nature’. While effectively demolishing some attempts to formulate a precise notion of cultural information that could support a formal theory of cultural change, he argues that in practice, most evolutionary cultural theorists have no need of a formal definition, and can operate quite successfully with a rather broad, informal concept; if ‘the search for cultural information is the search for those factors that explain the organisms dispositions to behave appropriately’ (58), this can encompass a wide and disparate range of factors, with varying degrees of susceptibility to formal definition; but this does not damage the project of mapping and modelling the information flows that are involved in cultural change.
The central section of the book is devoted to an extensive critique of the concept of human nature and its role, or lack of it, in cultural evolution studies. While certainly exposing a number of difficulties with attempts to make the intuitive notion of human nature watertight, Lewens' critique did not wholly convince me. In the first place, he appears to assume that anyone wishing to uphold this notion is committed to ‘restricting the attention of evolutionary scientists to . . . traits that are universal’. I cannot see that holding that there exists a significant core of traits that are universal to humans, and that can be identified with the intuitive notion of human nature, entails any such commitment – traits that are variable, so not part of human nature, surely remain just as much worthy of study. So this argument, on which Lewens puts significant weight, seems to me to lack force.
Much more serious, and I think to a large extent valid, are a group of objections centred on the difficulty of clearly differentiating between behavioural traits that are genetically inherited and those that are culturally transmitted. Partly this is a consequence of the progressive breakdown of the ‘classical’ neo-Darwinian view of genetic inheritance, assuming a one-to-one correspondence between DNA sequences in the genome and inherited traits (forcefully documented in Evelyn Fox Keller's classic study ‘The Century of the Gene’), and it's replacement, in the hands of many geneticists, by a Developmental Systems Theory approach, viewing the characteristics of the developed organism as dependent on complex interaction between (perhaps among others) genetic, epigenetic, environmental and cultural factors, such that one cannot meaningfully isolate distinct cultural and genetic ‘channels’ of inheritance.
This critique is underpinned by detailed treatment of the example of the linked evolution of pastoralism and lactose tolerance; on the face of it, it might appear that the former is a straightforwardly cultural development, the latter strictly genetic, but this appearance is deceptive. It turns out that, though there are genetic factors influencing lactose tolerance, it is also affected by cultural ones such as other elements of diet, stress levels, etc. Conversely, genetically determined variation in physiology, etc., might be important in predisposing some groups in favour of or against pastoralism.
Lewens succeeds, in my view, in establishing that the distinctions implied by the idea of human nature, between genetically and culturally transmitted characters and between behaviours characteristic of a species and those that are subject to variation, and so forth, cannot be made absolute and watertight; and I agree with him in endorsing the Developmental Systems approach, which stresses the highly interactive nature of the effects of different sources of variation in development, and repudiates the idea of hermetically separated ‘channels of inheritance’.
But all this does not seem to me to amount to a comprehensive refutation of the coherence and value of the concept of human nature. The possibility of genetic influences being overridden by cultural, or other, factors is a matter of degree, and the fact that we cannot assign sharp boundaries to the set of human chacteristics that are universal, or nearly so, in virtue of our common genetic inheritance does not render the concept meaningless. Surely, for example, we should count the capacity to acquire language as part of human nature, even though that capacity is not shared by absolutely all humans, and may not be brought to actualisation in some due to lack of appropriate cultural influences. Lewens' critique provides a number of important caveats against careless use of the concept, but I feel it yet deserves deeper investigation, if the baby is not to be thrown out with the bathwater. (I regret that there is not space in this review to do the point justice.)
The following two chapters return to the assessment of the ‘Kinetic’ approach, qualifying his earlier endorsement of this as the most promising general approach to the evolutionary study of culture with some quite strong reservations about the incautious use of statistical models of cultural change. He shows that an illusion of explanatory force is easily generated in the application of such models when insufficient care is taken to validate their underlying empirical assumptions, to formalise these in appropriate ways, and to verify that alternative hypotheses might not explain the phenomena as well or better. He next considers the objections of Lewontin and others to statistical approaches, that they are unable to take account of the significant impacts upon historical processes of individual actors, or indeed of significant collectives such as trades unions or universities. This objection seems to me potentially very strong, more so than is represented by Lewens; any such quantitative model of historical change will retain its validity only within a quite constrained set of historical circumstances, and this severely limits the range of application of evolutionary approaches.
Notwithstanding this, Lewens' final verdict, that provided the conceptual traps that have bedevilled many attempts to apply evolutionary thinking to the study of culture are clearly understood, and the limits of its applicability observed, it has a valuable role to play, particularly within the limited domain where populational modelling and related techniques are applicable, is sound, and on the whole he has done an excellent job of pinning down the pitfalls and delineating the areas where this approach is fruitful. If the book has a significant defect, it is that the last of the four general approaches described in the first chapter, that of the broader historical synthesis, well exemplified by Darwin's later work, much of which touched on cultural evolution, receives insufficient attention. Indeed, it is to such a synthetic approach that Lewens gestures toward the end of the book, intimating that, to be of most value, evolutionary thinking needs to interface strongly with a number of other disciplines. A further study that explored this line of thought with the same degree of methodical rigour exemplified in the present work would be a most valuable contribution.
