Evolutionary Psychology: Neglecting Neurobiology in Defining the Mind
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Brad M. Peters, Department of Psychology
Saint Mary’s University, Halifax, NS
Evolutionary psychology defines the human mind as comprising innate and domain-specific information-processing mechanisms that were designed to solve specific evolutionary problems of our Pleistocene past. This model of the mind is the underlying blueprint used to engage in the kind of research that characterizes the field: speculating about how these innate mechanisms worked and what kinds of evolutionary problems they solved. But while evolutionary psychologists do engage in research to confirm or disconfirm their hypotheses, the results of even the most rigorous studies have been open to alternative, scientifically valid means of interpretation (e.g. Buller, 2005; Richardson, 2007), which puts into question the falsifiability of their claims and whether these are truly ‘scientific hypotheses’ being tested. What constitutes as ‘evidence’ would seem to vary in accordance with the theoretical assumptions of those viewing it (Kuhn, 1962). Arguments about, or appeals to ‘the evidence,’ may thus involve little more than theoretical bible-thumping or pleading for others to view the ‘facts’ from their preferred theoretical perspective. When theoretical paradigms are unable to agree on what it is that they are looking at, it reminds us that the data is anything but objective, and gives good reason to question the theoretical blueprints being used. This paper argues that evolutionary psychology’s assumptive definitions regarding the mind are often inconsistent with neurobiological evidence and may neglect very real biological constraints that could place limits on the kinds of hypotheses that can be safely posited. If there are problematic assumptions within evolutionary psychology’s definition of the mind, then we also have reason to question their special treatment of culture and learning and the paradigm as a whole. It is finally suggested that the mind can be adequately understood and its activities properly explained, without hypothetical appeal to countless genetically pre-specified psychological programs, and in a way that remains consistent with both our neurobiology and neo-Darwinian evolution.
Evolutionary Psychology: Defining the Mind
In defining the mind, evolutionary psychology essentially combines Darwin’s notion of adaptation with the assumptions of cognitive psychology:
Evolutionary psychologists suggest that the human mind is a complex integrated assembly of many functionally specialized psychological adaptations that evolved as solutions to numerous and qualitatively distinct adaptive problems . . . Psychological adaptations are information-processing circuits that take in delimited units of information and transform that information into functional output designed to solve a particular adaptive problem. (Confer et al., 2010, p. 111)
The foundation of evolutionary psychology is based on an assumption that the mind works somewhat like a computer – made up of genetically pre-specified and domain-specific mental algorithms, or computational programs, originally designed to solve specific evolutionary problems of the past. These hypothetical mental mechanisms are often referred to in the literature as modules, and the above mentioned assumptions comprise what is often referred to as the modular theory of mind. It should be noted that there has been considerable debate about whether the mind is massively, moderately, or non-modular. A mind that is massively modular (Fodor, 1983) would be comprised almost entirely of pre-specified incompressible mental programs or modules; a moderately modular mind (Carruthers, 2003) would be mostly modular in composition, while the non-modular mind would be almost entirely domain-general and non-modular in composition. For the purpose of this discussion, I will focus on the prevailing view within evolutionary psychology. Though there is some theoretical variation within the field, this position would appear to lie somewhere between moderately and massively modular assumptions (Tooby & Cosmides, 1992; Pinker, 1997), with modules being by definition, relatively distinct, though at times proposed as being functionally connected with other modules (Tooby, Cosmides, & Barrett, 2005). Within the literature of modularity, there has also been debate regarding the innateness of modules, though again, for the purpose of this discussion, I will focus on the prevailing position within the field. This view assumes that modules are largely pre-determined or pre-specified in our genes – a qualification accepting that the environment may also play a role in their activation (discussed later). An example of a module may include specific fear-detection mechanisms, which are thought to be sensitive in responding to certain kinds of environmental stimuli (e.g. snakes; Ohman & Mineka, 2003), and are argued to have been beneficial during what they call the Environment of Evolutionary Adaptedness (EEA) – presumably, our Pleistocene past. And since these hypothetical modules are assumed to be somehow encoded in our DNA, they are presumed to be heritable; organisms that survived would have an increased probability of passing the successful genetic information, and presumably the ‘mental programs,’ on to its offspring.
Cosmides and Tooby (1992) suggest that: “the brain is a physical system. It functions as a computer.” For evolutionary psychologists, the environment offers a vast array of potential ‘input,’ for our countless innately pre-specified biological programs to ‘compute.’ Thus, certain environmental stimuli have a priori meaning as ‘information’ or potential ‘input,’ since it is assumed that genetically specified and domain-specific mental program(s), designed to solve specific evolutionary problems, must be capable of identifying specific input as meaningful. In this model, psychological meaning is largely assumed to be pre-specified in our genes. Modern influences, including culture, environment, and learning take on a different role for the evolutionary psychologist. For them, the environment has already played its biggest part – during the EEA. While modern environmental forces may offer ‘proximal’ influence or input, they are not regarded as the ‘distal’ or ‘ultimate’ sources of influence within the causal chain.
Evolutionary psychologist’s frequently give examples such as our reflex upon touching a hot stove. The nociceptive circuits in this case trigger a meaningful innate reflex causing us to recoil. All of this happens without our having necessarily had any first-hand or vicarious experience with hot stoves, and without our needing to think about the physiological consequences of burning our limbs. The ‘proximate’ cause is the hot-stove, while the ‘distal’ cause is a genetic prewiring what prepares our nervous system to recoil in such situations – presumably because organisms that could do this quickly would have had a better chance of survival. Examples such as this these, show that our nervous system is often capable of innately identifying some internal neurophysiological representation as meaningful. But is that the case for all psychological processes? If so, where is the evidence? If not, how do we know where to draw the line?