The explanatory power, and successful rise, of behavioural ecology stems from three core theoretical frameworks emerging in the 1960s and 1970s:
1. Hamilton’s (1964a,b; see Fig. 1.14) notion of inclusive fitness, which recognised related-ness as an indirect route through which alleles affecting social interaction could influence their transmission to subsequent generations, thereby revolutionising evolu-tionary explanations of social behaviour and phenotypic altruism.
2. The concept of evolutionarily stable strategies (ESSs) (Maynard Smith 1972), which recognised that adaptive decision-making was often frequency-dependent (the best thing to do depends on what everyone else is doing).
3. The development of economic models of decision-making (of which ESS models are a special kind) that used cost/benefit analysis and optimality theory as a framework for predicting evolutionary outcomes (Parker 1970; Schoener 1971; Charnov 1976a,b).
The rationale behind each of these is discussed in detail in Chapter 2.
Behavioural ecology has also been accused of Panglossism, after the character Dr Pangloss in Voltaire’s Candide, whose philosophy was that ‘all was for the best in the best of all possible worlds’, meaning everything in life was as good as it could pos-sibly be. In a landmark paper, Gould & Lewontin (1979) used Pangloss to parody the kind of adaptive explanation promulgated by behavioural ecology and its subdiscipline sociobiology, suggesting that it uncritically viewed every aspect of an organism as an adaptation to something and encouraged a naïve perfectionist view of the design of organisms. However, historical (phylogenetic) constraints, and those imposed by alternative demands on the animal, have long been recognised as factors limiting the evolution of perfect adaptation in the sense implied by Gould & Lewontin (Dawkins 1999, and see Chapter 2).
The bogey of genetic determinism has been another problem (see 5.1). The use of ‘genes for’ language (Chapter 5) in explaining the evolution of behaviour has led to misunderstanding about the role of development and the environment in adaptive decision-making (Lewontin et al. 1984; Lewontin 1991; Dawkins 1995). The approach is often caricatured as implying rigidly encoded behaviour patterns that are always performed in a particular way like an automaton, or as somehow justifying antisocial behaviour and social stereotyping in our own species because it offers a plausible evolu-tionary explanation for them (the crux of much of the opposition to sociobiology).
Dawkins (1989, 1999) once again provides a readable antidote to this kind of muddled (or in some cases mischievous) argument, to which we shall return in Chapter 5.
1.3.4 Evolutionary psychology
Psychology is an older science than animal behaviour. Yet it is the younger discipline that captures the wider imagination. Why should this be? The most likely reason is that animal behaviour has its roots in natural history and evolutionary biology, which together can tell us something about why we are what we are and how we came to be.
Evolutionary thinking has been remarkably lacking, though not entirely absent, from contemporary psychology and we have already seen a consequence of this in the contretemps with the ethologists. There are good historical reasons for this odd impoverish-ment (Buss 1999; Plotkin 1999). One is that comparative psychology pre-dated the temporary demise of Darwin’s theory of natural selection in the early years of the last century (see Nordenskiöld 1928). While the onslaught on Darwinism came largely from the early geneticists, psychology suffered by association because Darwin, and later his student Romanes, speculated about behaviour and its evolutionary origins. This was compounded by the early post-Darwinian rush to ascribe human behavioural traits, indeed the perceived behavioural traits of entire nations, to simplistic inbuilt instincts inherited from our animal past. William James in particular saw instinct in everything, from biting, sleeping, sitting up and walking in infants to imitation, fear of certain objects, shyness, sociability and parenting in adults ( James 1890). Flying in the face of contemporary opinion, James claimed that humans possessed more instincts than any other species, but his long, atomised lists of putative examples soon came to be ridiculed.
Concepts based on a crumbling theory were thus easy prey and their vulnerability paved the way for a school of thought that banished evolutionary thinking from psychology for the best part of half a century: behaviourism.
The beginnings of behaviourism can be traced to John B. Watson’s seminal paper in the Psychological Review in 1913. Behaviourism rejected any explanation of behaviour 1.3 n Approaches to the study of behaviour x 29 AB_C01.qxd 9/17/07 8:00 PM Page 29
that depended on unobservable causes. Thus mental states and concepts such as instinct were not the province of scientific explanation because they had no tangible reality; they were hypothetical constructs and thus immune to scrutiny. Evolutionary explanation was given short shrift precisely because it relied on inference and hypothesis about history rather than direct measurement of the physical present. The cause célèbre of behaviourism was the study of learning which emerged from the early experiments of Pavlov (Fig. 1.14) and Thorndike and, from the 1920s onward, provided psychology with its main claim to be an empirical science (Plotkin 1999). This emphasis on learning, and the quest for the general laws that underpinned it, did two things. It encouraged an inflated confidence in ‘nurture’ as the major determinant of behaviour and behavioural abnormalities, and ensured a mechanistic, physiological focus in the causal explanation of behaviour.
With minor perturbations, and reinforced by the blossoming discipline of cultural anthropology, this perspective held sway until the 1960s when certain empirical findings began seriously to undermine the concept of general laws of learning. Chief among these were Harlow’s studies of mother–infant relationships in monkeys and Garcia’s experiments on associative learning in rats (see 6.2.2).
Harlow’s studies demonstrated the limited power of reinforcement in shaping mother object preferences in young monkeys; infants could not be persuaded to prefer a wire mesh ‘mother’ over a soft cloth version, no matter how strongly contact with the former was rewarded with food (e.g. Harlow & Zimmerman 1959). Garcia’s work showed that associative learning could be highly dependent on the form of stimulus–
response relationship and that basic tenets of temporal association between stimulus and response could be violated without jeopardising the formation of an association (Garcia & Koelling 1966). In short, animals found some things easy to associate and some things difficult or impossible. Moreover, things that were easy to associate could be linked even when presentation and consequence were separated by several hours.
Clearly, learning was not an homogeneous, generalised property of living organisms that could be accounted for solely by reinforcement. Instead it was honed to respond selectively to things that were likely to be important in the day-to-day survival (and thus ultimately the reproductive success) of the individual.
These findings helped pave the way for a renaissance of evolutionary thinking in psychology. They led to a new perspective on information processing and the integra-tion of sensory input and motor output that could be generalised to human cognitive attributes. Perhaps humans too were designed to respond to certain kinds of informa-tion but not others in order to further their reproductive interests. Indeed, might not the entire architecture of the brain and its legion capabilities have been shaped by the forces of natural selection? If so, a science of evolutionary psychology would seem an essential starting point for any understanding of brain and mind. A new and flourishing literature shows that many agree, and evolutionary psychology is now emerging as a productive, and (as ever with human behaviour) contentious, new field of enquiry (12.2).
While it is often defined in terms of an evolutionarily informed study of human mental attributes, Daly & Wilson (1999) rightly point out that evolutionary psychology draws ideas from a wide range of intellectual and taxonomic sources. Many contributors are neither psychologists nor do they work on humans; they are interested in the commonality of cognitive processes in humans and other animals as we might expect natural selection to have shaped them. In the main, evolutionary psychology has reflected an extension of behavioural ecology. Thus ideas align along the characteristic subject divisions of beha-vioural ecology: sexual selection, social behaviour, kinship, reciprocity and cooperation,
parental investment, conflict and aggression (Buss 1999; Daly & Wilson 1999; Barrett et al. 2002). They are sometimes based on the concept of an environment of evolutionary adaptedness (EEA) (Bowlby 1969; Tooby & Cosmides 1990; Daly & Wilson 1999), a reflection of the critical selection pressures that have shaped mental processes in the past (Tooby & Cosmides 1990) and which are thus essential to understanding responses to environments in the present. Perhaps not surprisingly, the nature of any such EEA, indeed its usefulness as a concept at all, is a matter of some debate (Chapter 12).
Summary
1. ‘Behaviour’ includes a wide range of responses, from simple movements of a limb to complex social interaction. In order to study it we must break it down into measurable units that can be recognised reliably each time they are performed. Sometimes units are simple actions such as batting an eyelid, but more often they are sequences of actions that produce a functional outcome, such as finding food or escaping from a predator.
2. The fact that behaviour patterns frequently have a functional outcome gives them an air of purpose. It is tempting to attribute apparent purposefulness to a pre-conceived goal on the part of the animal. However, several different mechanisms could give rise to the appearance of purpose, each assuming very different things about the internal processes of the animal and its perception of the external environment.
3. The same functional outcomes can be achieved through very different mechanisms of decision-making. Decisions may be ‘hard-wired’ into the animal so that it always does the same thing when a response is required, or they may be devolved to a higher-level centre that integrates incoming and stored information and responds flexibly to the demands of the moment. Deciding which kind of decision-making process is responsible for behaviour can be difficult.
4. Questions about behaviour can be answered at four different but complementary levels, generally known as Tinbergen’s Four Whys. Answers can be in terms of function (how the behaviour helps the animal survive and reproduce), mechanism (the underlying mechanisms producing the behaviour), development (the embryological or other developmental factors influencing the behaviour) or evolution (the historical selection pressures and phylogenetic constraints that have shaped the behaviour).
5. Questions at any of these four levels can be investigated by a number of methods:
experimentation, observation, comparison and modelling. In many cases combinations of these methods are used.
6. Various traditions of behaviour study have given different emphasis to the Four Whys.
While ethology maintained a broad basis in all four, comparative psychology has tended to emphasise mechanism and development while behavioural ecology has emphasized function and evolution. However, these kinds of traditional biases are now disappearing, both within existing approaches and in emergent new fields such as evolutionary psychology.
Summary x 31 AB_C01.qxd 9/17/07 8:00 PM Page 31