Promises and Pitfalls of Interdisciplinary Legal Research: The Case of Evolutionary Analysis in Law

is more, we have just argued that the Darwinian work to date is at best seriously incomplete. We make no apology for this. Science is an error prone, one-step-at-a-time procedure, and the story shall remain incomplete for a long time if not forever. The only thing about the project that we care to assert with utter conviction is that the Darwinian approach is worth pursuing. Those who engage in the pursuit will take proper delight in remedying our generation’s errors and omissions!1


I WOULD LIKE to begin my chapter with a quote I happened to find in Mark Van Hoecke’s inaugural lecture, on a topic similar to the one at hand in this volume, delivered at Ghent University in February 2009. It is a quote from Christopher Columbus Langdell, from his 1886 Address to the Harvard Law School Association, and it goes like this:

[t]he library is the proper workshop of [law] professors and students alike; that is to us all that the laboratories of the university are to chemists and physicists, all that the museum of natural history is to the zoologists, all that the botanical garden is to the botanists.2

The use of this quote at the beginning of a lecture questioning, but ultimately affirming the scientific nature of legal (doctrinal) research,3 immediately struck me, because I had just been reading Ernst Mayr’s collection of papers entitled Toward a New Philosophy of Biology: Observations of an Evolutionist.4 As some readers undoubtedly will know, Ernst Mayr is considered to be one of the principal architects of the so-called Modern Evolutionary Synthesis, the synthesis of Mendelian genetics and (neo-)Darwinian evolutionary theory, a synthesis that is still widely regarded as biological orthodoxy – although things are perhaps slowly beginning to change in this respect.

In this collection, there is an essay called ‘Museums and Biological Laboratories’ that Mayr wrote in 1973 for the opening of the laboratory wing of the Museum of Comparative Zoology at Harvard University. While on the one hand clearly acknowledging the continued usefulness of the collections of museums of natural history for biological research, Mayr on the other hand points to the fact that many crucial biological questions cannot be answered simply by the study of preserved material.5 He also shows us that this is far from being a new idea.

Indeed, Mayr also quotes the founder of the Museum, Louis Agassiz, namely from his 1857 ‘Essay on Classification’, as follows: ‘Without a thorough knowledge of the habits of animals’, [Agassiz] said, ‘it will never be possible to determine what species are and what not.’ He goes on to say that we want to find out ‘how far animals related by their structure are similar in their habits, and how far these habits are the expression of their structure’. He continues: ‘How interesting it would be a comparative study of the mode of life of closely allied species.’ Indeed, Agassiz proposes a programme of study which is virtually identical with that of the founders of ethology6 more than 50 years later.7

So what we see here is that, some 30 years before Langdell gave his address, zoologists at least already clearly expressed an interest in the behaviour of live animals, rather than merely focusing on the remains of dead animals. In more recent times, this interest in the behaviour of live animals has led to the development of ever more research methods, like both laboratory and field experiments, mathematical modelling and quite advanced statistical methods, and the incorporation of molecular biology and behavioural genetics, to name but a few of them.8 So while the collections of specimens in museums of natural history continue to serve some function in biological research, I believe it is fair to say that they have been superseded by other types of data collection and analysis.

The central question of this essay then becomes the following: Should, paraphrasing Langdell, the library remain the proper workshop of law professors, given that zoologists in the meantime have moved far beyond the museums of natural history that once indeed were their main working area? While the first part of this question is of course by no means novel, perhaps even to the point of having become anachronistic, I hope to be able to add some elements to this debate by addressing it from the viewpoint of the question’s second part. More particularly, my interest in the dealings of zoologists past and present stems from the perspective I have adopted in my current research: that of evolutionary theory as applied to the human species.9

After a necessarily brief introduction on these contemporary evolutionary approaches to human behaviour and the ways in which these approaches have (or have not) been put to use in legal analyses (see section II. below), I will try to position what has been called Evolutionary Analysis in Law – or perhaps evolutionary analyses in law would be a better term – within some of the more recently proposed classificatory schemes regarding legal methodology and interdisciplinary legal research (see section III. below). This should not only allow me to touch upon some of the respective strengths and weaknesses of these taxonomies, but, in so doing, will also allow me to address methodological questions of a more theoretical nature as they arise when pursuing interdisciplinary research. Could contemporary evolutionary approaches to human behaviour be of assistance in overcoming some of the traditional social science dichotomies that are often reproduced in legal scholarship (see section III. A. below)? Should legal scholars engage themselves in recent attempts at unifying the life and social sciences? Or is ‘methodological integration’ more valuable than such ‘theoretical integration’ (see section III. B. below)? Finally, would all this amount to little more than one-way traffic – from the various behavioural sciences to legal research – or is there room for at least some measure of cross-fertilisation originating from within the legal sciences (see section III. C. below)?


A.  Contemporary Evolutionary Approaches to Human Behaviour

In order to be able to address these questions relating to the methodology of interdisciplinary legal research, however, I must first say a few words on the three different styles in the evolutionary analysis of human behaviour that are currently usually distinguished from one another. These three approaches are as follows:

  • Evolutionary psychology, or the specific version of evolutionary psychology that is more and more often referred to as ‘narrow’ Evolutionary Psychology or Evolutionary Psychology sensu stricto.10
  • Human behavioural ecology.
  • Dual inheritance theory, sometimes called gene-culture co-evolutionary theory or simply cultural evolutionary theory.

I will, as briefly as possible, give the main characteristics of these three approaches as well as their main differences and refer the interested reader to the original sources cited in this section for more elaborate discussion.11 Since such a brief – perhaps too brief – overview may suggest to some readers that these different approaches are in effect incompatible, I should emphasise at the outset that most commentators on this subject, while acknowledging or even emphasising theoretical disagreements, do appear cautiously optimistic as to the prospects of their eventual (re-)integration.

i. Evolutionary Psychology

Evolutionary psychology is the contemporary evolutionary approach to human behaviour that is currently presumably still the most popular and in any case the most visible in the popular press. Evolutionary Psychologists sensu stricto,12 like John Tooby and Leda Cosmides, argue that the human brain is the result of evolution by way of natural selection having operated in the remote past – our ‘environment of evolutionary adaptedness’ or ‘EEA’. Hence, they propose to explain human behaviour by appealing to specific genetically evolved psychological mechanisms that are adaptations to specific features of this EEA. They also emphasise that this adaptedness to ancestral environments will frequently lead to maladaptive behaviour in our current environments – the so-called adaptive lag hypothesis. Moreover, they claim that our human species-typical psychological mechanisms are characterised by so-called domain specificity and massive modularity – so that our brain consists of a great many modules that are highly specialised to perform certain specific tasks. More general purpose mechanisms, involving ‘learning’, ‘culture’ or ‘rational choice’, are regarded as insufficiently domain-specific and modular to serve as plausible outcomes of the process of natural selection. Unsurprisingly, evolutionary psychologists are highly sceptical of views of the human mind as a blank slate, engraved only by experience and culture, allowing for a nearly infinite malleability of the behaviour to which it gives rise – a view they derogatorily call the ‘Standard Social Science Model’. Finally, the characteristics of evolutionary psychology’s theoretical framework are reflected in their threefold division of the phenomenon of culture. The set of universal psychological mechanisms with which we are endowed and the resulting behavioural patterns are called ‘metaculture’. Different behavioural patterns that are triggered by different environmental cues are called ‘evoked culture’. ‘Epidemiological culture’ or ‘transmitted culture’ refers to what most people would recognise as comprising culture, namely a complex of shared beliefs, values, customs, etc.13 Here I think it is fair to say that the quest for a ‘metacultural’ universal human nature appears high on the evolutionary psychologists’ agenda.

ii. Human Behavioural Ecology

The second approach, human behavioural ecology,14 essentially views human behaviour as consisting of adaptive responses to varying environments and variation in human behaviour as a result of ecological variation, eliciting different optimising responses. In so doing, human behavioural ecologists assume that humans display a high degree of ‘phenotypic plasticity’, that humans are capable of flexibly adapting their behaviour to particular environmental factors. Unlike evolutionary psychology, human behavioural ecology focuses on current circumstances and expects humans to be overall well adapted to the environments in which they currently live. Existing behavioural diversity is largely explained as a consequence of differing contemporary socio-ecological environments that evoke different conditional behavioural strategies or decision-rules which dictate the most adaptive behaviour under the given ecological conditions (‘In context X, engage in strategy A; in context Y, engage in strategy B’).

iii. Dual Inheritance Theory or Gene-culture Co-evolutionary Theory

Third and finally, proponents of dual inheritance theory or gene-culture co-evolutionary theory,15 like Robert Boyd and Peter Richerson, focus on transmitted culture. They are interested in finding out how genetic evolution could give rise to cultural capacities in a species like ours and how these cultural capacities then affect (cumulative) cultural evolution. Dual inheritance theorists consider culture to be a whole of ideas, values, knowledge and the like that is learned and socially transmitted between individuals. Since cultural information exhibits the characteristics required for evolution by way of natural selection – namely variation, retention and selection, they argue that Darwinian methods can in principle be used to analyse cultural evolution, important differences between biological evolution and cultural evolution notwithstanding. While cultural evolution, in their theoretical framework, can result from a wide array of possible forces (including, among others, random forces and natural selection on cultural variants), Boyd and Richerson and their collaborators have been primarily interested in modelling the evolution of so-called decision making forces, mainly cultural transmission biases. They plausibly argue that genetically evolved learning biases, leading people to preferentially acquire some cultural variants rather than others, can be important forces in cultural evolution. Such learning biases could include a frequency-based conformity bias and a model-based prestige bias, which, for instance, can both help to maintain stable variation between different cultural groups and their respective social norms. Finally, dual inheritance theorists also address the interactions between the cultural and the genetic system of inheritance. This aspect of their theoretical framework is often referred to as gene-culture co-evolutionary theory and aims at elucidating the complex feedback relationships between these two inheritance systems.

B.  Evolutionary Analysis in Law

Now how have these contemporary evolutionary approaches to human behaviour been put to use in legal analyses? Well, to answer this question, we need to take a closer look at the work of Owen Jones, founder of the Society for Evolutionary Analysis in Law. His work can be regarded as both pioneering and representative for what is usually understood – by friends16 and enemies17 alike – to be ‘evolutionary analysis in law’. According to Jones, ‘effective law requires an effective behavioural model’ and such an effective behavioural model should integrate social-science models with life-science models – ‘including the effects of evolutionary processes on species-typical brain form and function’.18 As I have argued at length elsewhere,19 I think it is very important to realise that Jones’s views on the subject are heavily influenced by a very specific school of thought within the existing variety of contemporary evolutionary approaches to human behaviour – namely John Tooby and Leda Cosmides’s specific ‘narrow’ version of evolutionary psychology. To show this, I will briefly compare some of the basic features of their framework I have just outlined with some aspects of Jones’s work.

The striking resemblances between John Tooby and Leda Cosmides’s Evolutionary Psychology sensu stricto and Owen Jones’s influential approach to Evolutionary Analysis in Law are summarised in the table below.

John Tooby & Leda Cosmides’s Evolutionary Psychology

Owen Jones’s Evolutionary Analysis in Law

Environment of evolutionary adaptedness and adaptive lag hypothesis.

Time-shifted rationality and law of law’s leverage.

Domain specificity and massive modularity.

(Implicit throughout.)

Focus on ‘metaculture’.

Bio-legal history.

All of the key elements of the ‘narrow’ evolutionary psychological theoretical framework mentioned in the left column indeed reappear in Jones’s work on Evolutionary Analysis in Law.

Owen Jones includes the adaptive lag hypothesis in his framework, under the heading of ‘time-shifted rationality’. By this is meant that once adaptive behaviour may appear irrational in present environments. Understanding why this is so may consequently help to improve legislation aimed at counteracting this seemingly irrational behaviour. Closely related is a device called the ‘law of law’s leverage’, which stresses evolutionary psychology’s potential in distinguishing flexible, and hence legally modifiable, behavioural patterns from others which are less flexible and thus more resistant to legal influence.20

Evolutionary psychology’s claims regarding the domain specificity of human psychological mechanisms and the massive modularity of the brains that contain them are also, at the very least implicitly, present throughout this type of legal research.21

Finally, as regards the third feature, we can take a look at what Jones calls ‘bio-legal history’. The concept of bio-legal history refers to the assertion that ‘the legal features of any legal system will reflect . . . specific features of evolved, species-typical, human brain design’.22 So here again, there is a strong focus on what Tooby and Cosmides would probably prefer to call metaculture, or, if one wishes, on human universals. Evolutionary psychology apparently would be capable of providing us with ‘natural legal histories’ of some of the universal or at least recurring features of existing legal systems.23