Critique of Evolutionary Psychology
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Evolutionary Psychology: Neglecting Neurobiology in Defining the Mind
This is a draft manuscript that has been submitted to Theory & Psychology for review and publication. The final (edited, revised and typeset) version of this paper will be updated at a later time. Please do not reproduce or distribute without author permission.
Questions or comments can be sent to:
Brad M. Peters, Department of Psychology
Saint Mary’s University, Halifax, NS
Brad.Peters@smu.ca
Introduction
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?
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10 Responses to “Critique of Evolutionary Psychology”
I enjoyed reading this article–although EP authors have given me, at least, a strong impression that there is a significant interconnectedness between evolutionary drives and environmental learning, much more significant than what you discuss here. Perhaps you have interpreted this differently.
The most problematic area of this article, however, is its failure to address the most important aspects of evolutionary psychology, namely, cooperation, mate selection, and parental care (along with the vast array of resultant behaviours). These areas are the raison d’etre of EP. Many of the issues you raised about the overarching EP theory of mind are indeed interesting to evolutionary psychologists, but few will argue that EP lives or dies there.
I believe you have have perceived the causal chain of investigation to be reversed. You seem to think that evolutionary psychologists first conceive of the mind as modular, and then go on to explain phenomena in light of this (and indeed, some may do so). You would be correct, then, in asserting that if the mind is not modular, then the whole theory may well fall. However, the field’s most important works (in, for example, The Adapted Mind, The Handbook of Evolutionary Psychology etc.) are almost all about finding evolutionary adaptive phenomena, and then explaining these phenomena by postulating a modular theory of mind. The modular theory of mind is an (important) after-thought explanation, which appears to be the best explanation for the large variety of universal species typical behaviours–again, especially, or even mostly, involving issues of cooperation, mate selection and parental care.
Your paper seems to be more a critique of the modular theory of mind, and a good one at that. But if you want to effectively critique evolutionary psychology, you must discuss issues of evolutionary import like survival and reproduction, which are at the heart of the field. Perhaps you could change the title to directly address the modular theory of mind (that would be easiest).
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Brad Reply:
December 14th, 2011 at 8:05 pm
Thank you for your comments. Let me see if I can address a couple points:
Yes, evolutionary psychologists do see a great deal of interconnectedness between evolutionary adaptations and environmental learning… they talk about ‘evoked culture’ and other apparently epigenetic factors – the problem is that they end up conflating the two while the greatest emphasis is placed on invisible genetic programs without there being much reason for doing so and without significant regard for ruling out true environmental effects.
Yes, I am critical of the theoretical underpinnings of evolutionary psychology. In psychology there is a large explanatory gap between the ‘hard’ sciences and the ‘social’ sciences. In order to fill that gap we must take a bit of a metaphysical leap – we create a theory to explain or make sense of what we see. It is the foundation for any paradigm, and is very slippery as I explain here.
Evolutionary psychologists make certain assumptions as they go ‘looking’ for universal traits that are adaptive – they assume that there is a way that this could work physiologically and their assumptions minimize or downplay culture or the environment. The theory guides their approach. You seem to think that we can do psychology without having theories or making assumptions during the investigative process. I cannot see how that would work quite frankly.
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There’s a fascinating discussion between several evolutionary psychologists on the nuances of the concept of modularity as they use it in the comments to Herbert Gintis’ review of Robert Kurzban’s book. I think a careful reading of the dialog gives a good sense of the way evolutionary psychology envisions the mind and the range of viewpoints in that field.
http://www.amazon.com/review/R1XZI9091C3XGI/ref=cm_cr_rdp_perm?ie=UTF8&ASIN=0691146748&nodeID=&tag=&linkCode=
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It’s hard enough to define “modularity” for so simple a thing as a network — just nodes connected by links! — that I have to chuckle at how cavalierly the idea is thrown about in evolutionary psychology. On top of that, such mathematics as I’ve seen used in the field appears mired in an understanding of evolutionary dynamics which is twenty years or more out of date. Say, trying to solve everything with tricks which don’t even work for bacteria.
But I’m an outsider (and, as it happens, a friend of Rebecca Watson from her years in Boston) so my opinions are just faddish claptrap. Next of kin to creationism, really.
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“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)”
Some of which are unequivocally false. Take Buller on the Cinderella effect, the finding that step-parents are vastly more likely to kill their step-children than genetic parents, which Daly and Wilson attribute to the absence of fond familial sentiments that serve as a vehicle of kin selection in humans. Buller offers the alternate hypothesis that because of cultural stereotypes, step-parents are more likely to be investigated when a child dies, suggesting that the number of deaths caused by genetic and step- parents are comparable but most of the deaths caused by genetic parents are overlooked. His main source of evidence is a Colorado study which reviewed various categories of child deaths to see whether the cause was correctly determined and found that genetic parents were more likely to be erroneously exculpated than others. But Buller doesn’t even get the data from the study right– he compares the category of “parents” to “other unrelated (including boyfriend)” instead of the appropriate “other relatives (including step-parents)”. The mistake is not trival: the study concluded that 43% of the child deaths caused by parents were correctly determined as such, versus 47% for “other relatives (including step-parents)” and 86% for “other unrelated (including boyfriend)”. The appropriate comparison provides no support for his claim, which, moreover, is totally incompatible with other data available before the publication of his book. Daly and Wilson note that for his hypothesis to be true for the period they studied in Canada, genetic parents would have to be responsible for 500 child deaths per year, 125 times higher than the average number of reported child homicides, and in fact larger than the number of Canadian child fatalities from all causes except for disease and congenital defect. So unless Buller is positing secret mass graves beneath the soils of Saskatchewan, his hypothesis couldn’t possibly be true.
“which puts into question the falsifiability of their claims and whether these are truly ‘scientific hypotheses’ being tested.”
There’s nothing more routine in the sciences (particularly the social sciences…) than to be presented with two competing hypotheses which purport to explain the same body of data. The dispute is resolved through further experiments or observations whose results are compatible with one of the hypotheses but not the other. This does not make the hypotheses unfalsfiable or unscientific, to the contrary, this is precisely how one hypothesis supersedes another and science progresses. Generally speaking, though, a retrodiction of the sort advanced by Buller has less scientific value than the original hypothesis, because, unlike the original, it doesn’t make a risky prediction and attempt to falsify it. Buller is in the business of concocting just-so stories to explain existing data, a charge often but often inaccurately levelled against evolutionary psychologists.
“Our biology could conceivably accomplish functional organization by way of very basic, valence-laden neurobiological systems, interacting with our complex environments to dynamically shape the rest of the nervous system.”
You need to be a lot more explicit about how these “basic” neurobiological systems can account for the uniformity of human brain development under normal conditions. It’s also not clear how substantially the claim that regions of the brain have a strong innate “valence” to form a particular module differs from the modularity thesis defended by evolutionary psychologists, none of whom would object to the notion that the environment plays an integral role in brain development. I also don’t think any of your claims about neuroscientific consensus hold water– the literature is full of distinguished neuroscientists who are more or less on board with evolutionary psychology.
“If we accept that the human genome may put an upper limit on the number of pre-programmed adaptations investigators can comfortably hypothesize without potentially jeopardizing the rest of our genetic endowment”
Pinker points out in one of his books that animals with a small number of stereotyped, pre-programmed behaviors actually have smaller genomes than comparable animals with more flexible brains (I believe he compares ants and wasps). This may be because the (more) domain-general modules are built atop the existing cognitive architecture, and indeed, most of the adaptations hypothesized by evolutionary psychologists have clear antecedents in other primates at least. Status hierarchies, tool use, war, fear of snakes, tribalism, polygyny and even the rudiments of language can all be found in chimpanzees. So I’m not confident that your “dizzying array of distinct neurobiological modules unique to humans” is anything but a strawman.
“Would it not make more intuitive sense, for example, to have acquired biological systems that direct us to ‘fear and avoid environmental threats’ (e.g. things that evoke physical or emotional pain or discomfort)”
Not if the selection pressure is strong enough, no. You only get one chance with a black mamba, and by the time associative learning kicks in and you recognize it as a threat, it’s already too late. I’m inclined to think that selection would be remiss in its duties (to use a ghastly metaphor) if it left snake-avoidance up to the environment.
“However, those who reject the evolutionary psychology definition of the mind would not see a problem with a modest number of pre-specified valence-laden systems, since they ought to be ‘good enough’ to get the organism started while the environment takes a larger role in the ‘programming.’”
Today, yes, but this is only because evolutionary psychology and its progenitors have been so successful that its opponents have been forced to make substantial concessions. It wasn’t so long ago that the academy was dominated by behaviorists, marxists, Boasian cultural relativists, and radical feminists, most of whom would see your proposal as tantamount to genetic determinism and pillory you for it.
“But even if the trait in question is found to be ubiquitous across cultures, it still does not rule out the impact of culture. In an age of globalization, the universal spread of democratic and capitalistic values threatens the existence truly independent cultures. As cultures erode and our lived environments become exceedingly similar, it consequently becomes more difficult to measure the direct effects of our shared environments on personality.”
There are a number of problems with this claim. First, if an evolutionary psychologist or anthropologist studies a certain trait across dozens of different cultures, including remote tribes in the Amazon or New Guinea Highlands who have otherwise adopted few western customs, it’s not very plausible that every last one of them has by sheer coincidence cottoned to the same western cultural norm. Second, archaeological and historical evidence which predates western contact sometimes provides uncontaminated evidence of universality. Third, anthropologists who study remote tribes often inquire whether a certain cultural practice is recent or as old as living memory, using oral histories as corroborating evidence. Fourth, there is a startling variety of human behavior along some dimensions (e.g. sexual mores involving non-kin), and a startling uniformity on others (e.g. the mother-son incest prohibition), which cannot readily be explained by the diffusion of western values. Fifth, some cultural universals, like war and other forms of violence, are more pronounced in present-day stone age cultures than in the developed world. Sixth, some human universals are also hominin universals, or primate universals, or mammal universals, etc., in which case innateness is almost assured. To put it bluntly: many cultural universals are supported by a veritable mountain of evidence, and your dismissing them out of hand only serves to undermine your credibility.
“and evidence that such mechanisms are likely to have had genetically endowed origins,”
Be careful what you say here, because it sounds like you may be inadvertently challenging the heritability of psychological traits, which is not an item of serious controversy.
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Brad Reply:
June 10th, 2013 at 10:38 am
I respond to these comments in a separate post.
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What I said about genome length is wrong, but that’s okay, because there’s no relationship whatsoever between genome length and complexity or domain-generality. The longest recorded genome belongs to a protist, while mammals fall in between birds and lungfish. Humans are right in the middle of the pack for primates, and, of course, have barely diverged from the chimpanzee and bonobo.
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Since you also mentioned Richardson’s book, I’d like to take a poke at that, too. On page 16, Richardson makes the somewhat baffling claim that there are no venomous spiders native to Africa. This is simply false. There are, in fact, around a dozen known species of venomous spiders in Africa [1] (and probably many more in the depths of the Congo), only one of which is thought to be imported [2]. Reported fatalities are rare, but not unheard of– in fact, in 2007, the year Richardson’s book was published, an Irish nun in Kenya died from the bite of a huntsman [3]. What’s more, even spiders whose venom is not lethal in itself would have posed a much greater threat to our ancestors because of the risk of secondary infection. So there are good reasons to think that the fear of spiders, so common yet so irrational for most of the world’s population, may have been built into the human brain by selection.
I hope you will see the irony in a book which purports to expose the poor biology and shoddy research methods endemic in evolutionary psychology making such a glaring mistake in the first chapter, a mistake that could have been corrected with a cursory google search.
[1] http://www.biodiversityexplorer.org/arachnids/spiders/bites.htm
[2] http://scienceinafrica.com/old/index.php?q=2005/april/buttonspider.htm
[3] http://cathnews.acu.edu.au/705/16.php
[Reply]
Brad Reply:
June 10th, 2013 at 10:37 am
I respond to this comment in a separate post.
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