Evolutionary approaches to psychology hold the promise of revolutionizing the field and unifying it with the biological sciences. But among both academics and the general public, a few key misconceptions impede its application to psychology and behavior. This essay tackles the most pervasive of these.
Misconception 1: Evolution and Learning Are Conflicting Explanations for Behavior
People often assume that if something is learned, it’s not evolved, and vice versa. This is a misleading way of conceptualizing the issue, for three key reasons.
First, many evolutionary hypotheses are about learning. For example, the claim that humans have an evolved fear of snakes and spiders does not mean that people are born with this fear. Instead, it means that humans are endowed with an evolved learning mechanism that acquires a fear of snakes more easily and readily than other fears. Classic studies in psychology show that monkeys can acquire a fear of snakes through observational learning, and they tend to acquire it more quickly than a similar fear of other objects, such as rabbits or flowers. It is also harder for monkeys to unlearn a fear of snakes than it is to unlearn other fears. As with monkeys, the hypothesis that humans have an evolved fear of snakes does not mean that we are born with this fear. Instead, it means that we learn this fear via an evolved learning mechanism that is biologically prepared to acquire some fears more easily than others.
Second, learning is made possible by evolved mechanisms instantiated in the brain. We are able to learn because we are equipped with neurocognitive mechanisms that enable learning to occur—and these neurocognitive mechanisms were built by evolution. Consider the fact that both children and puppies can learn, but if you try to teach them the same thing—French, say, or game theory—they end up learning different things. Why? Because the dog’s evolved learning mechanisms are different from those of the child. What organisms learn, and how they learn it, depends on the nature of the evolved learning mechanisms housed in their brains.
An analogy with perception helps to illustrate the point. Organisms perceive by virtue of perceptual mechanisms in their brains and sense organs. To understand how these perceptual mechanisms work and what kind of output they yield, we must look to the causal process that built them: evolution. This is an uncontroversial idea when it comes to perception, but it is less widely appreciated that the same reasoning applies to learning. Organisms learn, and learning is crucial for behavior—but learning is made possible by brain-based learning mechanisms whose provenance lies in evolution. Learning and evolution are not conflicting explanations; they are natural explanatory partners.
Third, construing evolution and learning as automatically in conflict is a mistake because they are not even located at the same level of analysis: learning is a proximate explanation, whereas evolution is an ultimate one. (The proximate level of analysis explains how something works, whereas the ultimate level explains why it works that way, or why the system was built that way in the first place). To say that something is a product of evolution does not imply anything about how the behavior comes about during an organism’s lifespan: it may involve some learning, no learning, or a great deal of learning. The two kinds of explanations are thus compatible. (It is possible for specific evolutionary hypotheses to conflict with specific learning hypotheses, as when a particular evolutionary hypothesis yields proximate predictions that conflict with those made by a particular learning hypothesis. The point, however, is that it is not necessary for the two to conflict, and there are plenty of examples in which evolution and learning are perfectly compatible. The mistake is to think that the two explanations are automatically in conflict simply because one involves learning and the other involves evolution.)
Misconception 2: The Products of Evolution Must Be Present at Birth (or Must Emerge Very Early in Development)
A second common misconception is that the products of evolution must be present at birth—or, at least, must emerge early in development. But this is not how natural selection works: it builds adaptations that come online during the developmental phase in which they are needed, not just adaptations that are present at the arbitrarily selected moment of birth. Teeth, breasts and facial hair illustrate this well: they are all uncontested products of evolution, yet are not present at birth. Similarly, nobody doubts that birds have evolved the capacity for vision and flight, despite the fact that many hatchlings are capable of neither. To claim that a psychological tendency or behavior is produced by evolution is not to claim that it is present at birth, but rather that it develops reliably in all or most members of the species during the appropriate developmental stage of the organism’s life.
In order to develop properly, the products of evolution often require certain forms of environmental input—a point that leads directly to the next common misconception.
Misconception 3: Evolution Implies Genetic Determinism
No matter how widespread the belief, an evolutionary approach to psychology does not imply that behavior is genetically determined There are two ways to appreciate this point.
First, like all other life scientists, evolutionary psychologists subscribe to an interactionist view that states that everything in the mind, body and brain is jointly co-determined by genes and environment.
Second, an evolutionary perspective emphasizes the centrality of the environment, pointing out that it is crucial at every phase of the causal process: the initial evolution of adaptations, their development across the lifespan and their triggers in the immediate present. In other words, an evolutionary approach suggests that a) environmental pressures drive the evolution of adaptations in the first place, b) adaptations require environmental input to develop properly during an organism’s lifespan, and c) environmental triggers are necessary to activate the adaptation in the present moment. Across all three timescales of import, an evolutionary perspective places the environment center stage.
So why do (some) people persist in believing that evolutionary psychologists are genetic determinists? One possibility is that critics may be failing to draw a distinction between the fact that adaptations have a genetic basis and the idea that adaptations are genetically determined (all adaptations have a genetic basis, but are not genetically determined). Many critics may also be unaware of the widespread view among evolutionary scientists that species-typical evolved mechanisms usually have a heritability of zero. As with other misconceptions about evolutionary psychology, critics occasionally appear to have formulated their opinions without having engaged with the primary literature in the field.
Misconception 4: If a Behavior Varies across Cultures, It Is Not a Product of Evolution
This idea makes intuitive sense, but nonetheless misses the mark. The problem is this: evolutionary thinking does not suggest that behavior will be uniform across cultures, but rather that the neurocognitive machinery that produces behavior will be uniform across cultures. This is a very different claim.
Consider language. People who grow up in different cultures learn different languages. Does this mean that language abilities are not a product of evolution? Hardly. It simply means that natural selection has sculpted a universal ability to learn language—but the actual language you learn depends on where you grow up. Similarly, everybody in our species is equipped with mechanisms that orient us to social status—but since the markers of status may differ by culture or subculture, we grow up paying attention to the local status markers in our culture, and we learn to value and emulate those. Some evidence suggests that a similar process may be at work with disgust and with food preferences. Just because the outcomes—which foods one eats, or which language one speaks—differ across cultures, that does not mean that the underlying psychological mechanisms that generated those behaviors also differ across cultures. Cross-cultural variability in behavior can be, and often is, underlain by cross-cultural uniformity in the neurocognitive mechanisms that generate those behaviors.
This is a key distinction that bears repeating: most evolutionary approaches to psychology and behavior predict universality at the level of the information-processing structure of the neurocognitive mechanisms that produce behavior, not at the level of the final behavioral outputs themselves.
One way to understand this is by reference to evoked culture. Evoked culture refers to cultural differences between groups that arise from the combination of a universal psychological mechanism with environmental inputs that differ across cultures. This can be neatly expressed as a kind of informal equation: universal psychological mechanisms + environmental inputs that differ by culture = behavioral outputs that differ by culture.
Cultural differences in mating strategies illustrate this point. Cross-cultural studies show that differences in mating strategy across cultures can be predicted on the basis of operational sex ratio. In countries with a dearth of men, the culture tends to lean more toward short-term mating. In countries with a dearth of women, the culture tends to lean more toward long-term mating. Why? These dynamics can be understood in economic terms: the mating market is a kind of biological market in which the rarer sex has greater bargaining power. Because men, on average, have a stronger desire than women for casual sex, cultures with fewer men tend to shift toward more short-term mating. And because women, on average, have a stronger desire than men for committed mating, cultures with fewer women tend to shift toward greater commitment (note the on average proviso—there is plenty of variation within each sex, but studies nonetheless show a clear and robust average sex difference).
This is what is meant by evoked culture: a universal psychological mechanism, combined with environmental inputs that differ by culture, yields behavior that differs by culture. Crucially, not only does the cultural variation in mating behavior not conflict with an evolutionary explanation, it was actually predicted before the fact using evolutionary reasoning. This phenomenon—evoked culture—also appears to partially explain cultural differences in personality traits such as extraversion, openness to experience and sociosexuality.
The conventional wisdom in the social sciences is that cultural differences in a behavior imply that the behavior in question does not have an evolutionary basis. This seems intuitive, but the conclusion is unwarranted because evolutionary approaches to psychology predict cross-cultural universality at the level of information-processing mechanisms, not at the level of behavior. Cross-cultural variation in behavior is not only consistent with an evolutionary perspective, it can often be predicted a priori using careful evolutionary thinking.
Misconception 5: Evolutionary Psychology Doesn’t Pay Enough Attention to Individual Differences
There is some truth to this idea, especially if you turn the clock back twenty years.
Evolutionary psychology began with a focus on species-typical mechanisms and sex differences. At first glance, individual differences—especially heritable ones—appear more challenging from an evolutionary perspective, and it took researchers a while to start tackling the subject in earnest. Seminal early attempts included papers like this one, this one, this one and this one.
More recently, evolutionary psychologists’ interest in individual differences has grown apace, and we’re seeing progress in both explanation and prediction. Some recent theoretical papers tackling individual differences include this one, this one, this one, this one and this one. Some recent empirical papers tackling specific individual differences include this one on extraversion, this one on sexual jealousy, this one on disgust and mating strategy, this one on body odor, this one on personality trait covariation, this one on contributions to the public good, this one on moralizing behavior, this one on the effect of parasites and this one on a variety of individual difference variables. It is also common to see sections dedicated to individual differences in other, broader papers, such as this one on sex differences in jealousy and this one on emotions, or papers that advance hypotheses about individual differences, such as this one on the psychology of hunger. And here is an entire paper devoted to context effects, which are an important driver of individual differences in behavior.
Entire volumes in evolutionary psychology are now dedicated to the topic, as are chapters in handbooks dedicated to personality psychology and individual differences.
So, yes, it is true that evolutionary approaches to psychology began with the low-hanging fruit of universal and sex-typical mechanisms, but the last twenty years have witnessed a naissance of interest in individual differences, including increased emphasis on within-sex variation. This trend shows no sign of abating, and is likely to grow in scope, importance and empirical harvest over the coming years.
Misconception 6: Evolutionary Psychologists Think That Everything is an Adaptation
This canard just won’t die—though it is tenable only if you read misinformed critiques rather than the actual primary literature in the field.
In their published writing, evolutionary psychologists frequently state explicitly that evolution yields three kinds of products: adaptations, byproducts and noise. Beyond this theoretical statement, researchers also propose hypotheses about byproducts and conduct studies on byproducts.
For example, here, here and here are three conceptual papers that explicitly reject the notion that all aspects of our psychology are adaptations. This paper on adaptations, exaptations and spandrels explicitly discusses byproducts at length. This paper thoughtfully addresses the question of how to carry out an exaptationist program in psychology. Here is an excellent study suggesting that racism is an evolutionary byproduct, not an adaptation, and that it can be erased. Here is a paper suggesting that the higher prevalence of sexual fetishism among men is a byproduct of their easier-to-cross thresholds of sexual arousal combined with their biased sexual learning mechanisms. Here is an example of two prominent evolutionary psychologists claiming that homicide is a byproduct, not an adaptation, and here are the same two researchers (along with a third co-author) claiming that uxoricide and filicide are also byproducts. Here, here and here are examples of researchers explaining religion and belief in supernatural agents as a byproduct of other mechanisms, such as agency-detection mechanisms that are biased toward false positives, theory of mind mechanisms and the attachment system. My colleagues and I recently submitted a chapter titled “The Products of Evolution” to a new handbook of evolutionary psychology, and, unsurprisingly, byproducts are a central part of the chapter.
The disparity between this criticism of evolutionary psychology and what evolutionary psychologists actually say in their published work is remarkable. The only reason it isn’t surprising is that there are many other examples of misrepresentations of the field—you can find some good examples of such misrepresentations here, here, here and here.
Part of the problem is a philosophical disagreement about what adaptationism means. As many evolutionary psychologists understand the term, adaptationism is not a commitment to the idea that all or most features of our psychology will turn out to be adaptations once we’re done studying them. Rather, it is a heuristic and a methodological approach that involves testing hypotheses about potential adaptations—and then rejecting those hypotheses if the evidence is not in their favor. In other words, adaptationism is a working starting point and a research strategy that yields testable hypotheses, not some kind of religious commitment to the notion that a particular trait will turn out to be an adaptation before the trait in question has even been investigated. As a working method and a research strategy, it has borne a lot of fruit. As an unquestioned assumption, it would indeed be terrible—but working evolutionary psychologists don’t seem to use it that way. Observers can easily be forgiven for thinking that they do, because audiences have been repeatedly told so by prominent authors such as Stephen Jay Gould, who had a documented tendency to misrepresent his interlocutors’ views.
Misconception 7: Evolutionary Psychological Hypotheses Are Just-So Stories
It’s much easier to maintain this misconception if you don’t engage with the primary literature in evolutionary psychology. I’ve discussed this misunderstanding here, but would like to address it again for a broader audience in this essay. For those who aren’t familiar with the term, just-so storytelling refers to the unscientific process by which a psychologist notices something about human behavior, concocts a convenient explanation for it (in this case, an evolutionary one) and then decides to believe that explanation without further inquiry or testing.
There are two basic approaches to hypothesis testing in science. The first is the top-down method: the researcher uses a theory to generate a hypothesis, derives specific predictions from that hypothesis, and proceeds to test those specific predictions. It is almost impossible to make the mistake of just-so storytelling using the top-down approach, because the researcher is making predictions a priori on the basis of theory. Much research in evolutionary psychology employs this approach, beginning with theory and proceeding from there.
The second approach to hypothesis testing is the bottom-up approach: the researcher notices something about human behavior or psychology, comes up with a hypothesis that might explain that behavior, then uses this hypothesis to generate new predictions, and finally tests those predictions. Both of these approaches are normal and productive parts of science, but this second one (bottom-up) can potentially lapse into just-so storytelling if the researcher stops halfway through and simply accepts the explanation he or she has concocted without bothering to derive and test any new predictions from it. A researcher who does this is guilty of just-so storytelling. Fortunately, however, very few researchers in any scientific discipline make this egregious mistake (and in my experience, with a little effort you can even get undergraduate psychology students to avoid it).
If you survey the primary literature in evolutionary psychology, you’ll notice two things: 1) a lot of evolutionary psychological work employs the top-down approach, rendering this research essentially immune to the just-so charge. And 2) most of the bottom-up evolutionary research does not stop halfway through the process; rather, the researchers usually generate novel predictions from the hypothesis they just concocted, and proceed to test those novel predictions in new empirical studies. This means that most bottom-up work in evolutionary psychology appears not to fall into just-so storytelling either.
So why do so many people persist in the notion that evolutionary psychological hypotheses are just-so stories? Here’s a potential partial explanation. People might be under the impression that because 1) evolutionary psychology involves a historical element, and 2) we can’t peer directly into the past, this means that evolutionary psychological hypotheses are ultimately untestable, and must therefore be just-so stories. This kind of thinking is tempting, but it is wrong—and it misunderstands the nature of hypothesis testing.
First, consider the fact that if it were true that hypothesis testing is ultimately impossible in any field that contains a historical element, this would make all of the following fields unfalsifiable and riddled with just-so nonsense: cosmology, astrophysics, paleontology, archeology, geology and evolutionary biology. This is obviously wrong, and should serve as a warning sign to those who think the historicity of evolutionary psychology automatically renders its hypotheses unfalsifiable.
Second, this misunderstands the nature of hypothesis testing. Evolutionary psychologists don’t need to travel into the past to test their hypotheses at all—instead, their hypotheses may be informed by their (admittedly incomplete) knowledge of the past, but these hypotheses yield empirical predictions about what we should expect to see in the modern world. In other words, an evolutionary psychological hypothesis yields predictions about what we should find when we test modern humans under condition X. For example, if we want to test the hypothesis that disgust evolved to protect us from disease, we don’t need to travel back in time, nor do we need to have perfect and complete knowledge of the past. Rather, testing this hypothesis requires that we go out and test modern humans to see if, for example, people show stronger disgust in response to more pathogenic items compared to less pathogenic ones (they do), whether those with higher disgust and greater contamination sensitivity are less likely to have gotten sick recently (they are), whether humans can detect sickness in others via body odor (they can), whether disgust is downregulated when caring for one’s kin (it is), whether disgust is linked with mating behavior in the expected manner (it is), whether it activates an immune response (it seems to), whether it is upregulated during periods of immunosuppression (it appears to be) and whether priming people with pathogen salience makes them engage in the kind of behavior that reduces their likelihood of infection (it does). Yes, the hypothesis that disgust evolved to protect us from disease contains an implicit historical element. But testing the hypothesis does not require the researcher to travel through time or to peer into history—testing it requires the researcher to derive novel predictions from the hypothesis and test those predictions in the modern day.
This, I believe, is the crux of the issue. It is tempting to think that the partial historicity of evolutionary hypotheses renders them unfalsifiable, but this misunderstands the notion of falsifiability and the nature of hypothesis testing. As long as evolutionary hypotheses yield predictions about humans that can be tested in the modern environment—and they do—they are eminently falsifiable.
Conclusion
The point of this essay is not to suggest that evolutionary approaches to psychology are perfect. They are not, and there is certainly room for improvement. However, the widespread misconceptions discussed in this essay have impeded the field’s acceptance among both academics and the general public. And given that these concerns are largely unfounded, many people’s rejection of evolutionary psychology has little to do with its actual merits and limitations, and is predicated instead on a foundation of misconceptions.
Perhaps more importantly, these misconceptions impede the progress of psychology as a whole, because the science of mind and behavior cannot reach its full potential if it ignores evolution. There is simply no escaping the fact that our brains are a product of evolution, and that this has important consequences for how our minds work.
Scientists overwhelmingly agree that evolutionary theory is the integrative paradigm of the life sciences: it unites many different disciplines, explains a huge variety of known findings and predicts a dizzying array of new ones. Psychology is a life science too. It cannot help but fall under this umbrella.
Evolutionary approaches to psychology continue to make theoretical advances every year and yield new empirical discoveries every month. Instead of tilting at evolutionary psychological windmills, it’s worth making a good-faith effort to engage with what researchers in the field are actually saying and doing. Readers who do so may be surprised to see that what they find is often strikingly different from the straw men one comes across so often in the secondary literature. They may also reap a wonderful theoretical and empirical harvest, and begin to understand human psychology in a new light.
46 comments
I’d suggest one of the reasons why theses misconceptions exist (although, without a doubt, lack of reading the original literature and, more importantly, understanding the biological processes are also reasons) is people who do not know enough about EP making EP hypothesis. For example, I’ve seen quite a few people in Psychology mention EP explanations for their effects, based on no evidence and very simple conceptions of human evolution and evolutionary mechanisms more generally.
For example, I’ve seen a handful of people (who do not do EP, let’s be clear) explain psychological phenomena by positing how this phenomenon would help stone age / hunter-gatherer people (e.g., trying to find the “ultimate” cause of the phenomenon). Reading Leda Cosmides & John Tooby’s primer on EP, they state: “In [the EP’s] view, the mind is a set of information-processing machines that were designed by natural selection to solve adaptive problems faced by our hunter-gatherer ancestors”, so I’m thinking this is the sort of claim that leads people to say this sort of stuff. But many, if not the significant majority, of the information-processing modules of the human brain precede the stone age brain (C&T do explain that we did not exist ex nihilo in the stone age, of course, so some modules are older or earlier). The modules associated with all our perception, basic emotion, movement, reproduction, basic communication, decision-making, etc., were all developed before the stone age. So these “design” (or architecture) features existed before, and still exist today, because they may have been beneficial in certain times and just not a catastrophic disadvantage in others. So it seems a bit odd, unless you make the claim that the phenomenon is only human, to look for the ultimate cause of the phenomenon in the stone age. Also, the stone age spans millions of years, during which the brain had significant changes until it reached its modern features around 300.000 years ago. Is the foundational era of human architecture features the environment of 300.000 years (actually no, right, it is the changes that started before and culminated in 300.000)? What do we in Psychology know about how that environment was? Are we really ok with using tropes about stone age people to justify our effects? I’d leave the EP to the EPers.
Finally, my main irk with EP itself has to do with the use of teleological language (e.g., “designed by natural selection”). I think its really imprecise and unnecessarily anthropomorphic. Animals vary, some of them survive and reproduce, and it is the combination of variations over time that leads to specific brain architectures. The architecture, of course, may bring benefits and that may be, in some cases, why it still exists (although sometimes its innocuous variations or by-products, as we well know). But the main point is they did not emerge to provide those benefits, – they emerged through random variation and (as what is always a by-product of their emergence), may have then provided advantages in certain environments. I think (but this is an empirical question, of course) this is something that also leads people to reach misconceptions, namely of the “we are optimized for the stone age” (see paleodiet), “everything has to have provided a benefit in the stone age” type. Because when you talk about design, purpose, etc., optimization or at least “benefit-searching” is what comes to mind.
EP is so much easier for electrical engineers: just say ‘hardware, firmware, software’ and we got it. But it seems that EP opposition is mostly motivated. Some might like the idea that animals are people, but few like the idea that people are animals.
Isn’t the confusion over heritability caused by perhaps a poor choice of words. People are surprised to hear that a trait that is 100% inherited has a heritability of zero because they think of those two terms as being equivalent. I was surprised that this was not mentioned, though perhaps I missed it.
Humans and other animals want to have the illusion of control of their lives. In other words they want the world to be predictable. But that is not possible. In animal and bird experiments, if reinforcement becomes unpredictable, the subjects develop peculiar rituals like two steps to the left, three head bobs and a full circle turn around. These actions are called ‘displacement behaviours’. Humans do exactly the same, particularly in times of stress: three hail mary’s, jenuflect and take a sip of wine, or kill a goat while chanting. A survey of the world religions will give the whole scope of human displacement behaviours.
This is a really eye-opening piece. Thank you for writing Dr. Al-Shawaf. I pride myself on being someone really interested in Charles Darwin’s work and evolutionary history in general. But this piece (and indeed, other work from people in your friend, including your own) have really expanded my understanding of the evolutionary process. I think as someone with a background in biology, it was easy for me to see how far the theory can go when it came to an organism’s limbs or its reproductive cycle. But I think if you’re someone who takes Darwin seriously, evolutionary theory must necessarily apply to an organism’s psychology or behavior as well.
I must confess though, it wasn’t easy for me to see how that applies to us humans. And while I have a great deal of respect for evolutionary scientists of all backgrounds, there were some pending issues in my mind that I hadn’t yet really reconciled. I think your piece here has essentially addressed my concerns. And I want to thank you so much for all those links. Boy, though, I thought I was going to sleep early tonight!
I appreciate the care you took to address these topics diplomatically. I come from a background where we evolutionists are debating creationists, so civil discourse isn’t always a thing we can maintain (or indeed, have any say in). And it seems to me, when it comes to a debate between scientists, you did a really amazing job at being charitable to other people’s views. I know from my own work that this isn’t an easy thing to do. So, I commend you.
Misconceptions 4, 5, and 7 were really illuminating for me in particular. Really interesting stuff!
If I may kindly ask, for someone who isn’t deeply into evolutionary psychology but who has read several academic articles in this field, where would be a good place to start? I sort of feel like I know a lot of details here and there but never really got the core of the material, if that makes sense.
Anyway, really great article. I look forward to reading more stuff coming from this field, and your work too. Cheers!
If you’re into reading books, then Steve Stewart-Williams’ The Ape that Understood the Universe is the best place to start
Thanks for this article – I’ll use it to teach students how to spot misconceptions about evolutionary psychology! Your explanations are clear and even helped me clarify my thinking, esp. re: the historicity of evolutionary psychology. I especially appreciate the fact that it begins with the false dichotomy of evolution vs learning (the misconception I have to deal with most often!) Great explanation of why the two are not automatically in conflict. Thanks for this piece!
@John,
You pointed out below that underdetermination is a general problem that affects all sciences. That’s a fair question.
My answer is that underdetermination affects some sciences more than others because different sciences use different kinds of theories. Whether one characterizes physics theories as deductive-nomological or hypothetico-deductive, physicists do rely on decisive experiments based on predictions. Evolution is a different kind of theory, however. Descent with modification through natural selection is an inference to the best explanation, which is a form of induction that only appears weakly at the highest levels of theoretical physics (string theory vs. e8, maybe) and only lasts until a decisive experiment can be conducted.
Evolution is a powerful explanation because it unified the facts known in Darwin’s time and unified genetics later on. As powerful as evolution is as an explanation of biological phenomena, however, it’s a weak theory from an epistemological standpoint because it’s hard to conceive of an observation (a decisive experiment) that could falsify it the way physics theories can be falsified. Haldane joked that he’d give up evolution if someone found a fossilized rabbit in the Precambrian. But would that be enough? Would it be wise to toss out a theory that explains so much based on a single discordant piece of evidence? Or would the rational response be to hold out for some explanation of that piece of evidence? I think the latter. And this is a crucial difference between the epistemological structure of physics and biology theories.
This brings us around to evolutionary psychology (EP), which is in a worse epistemological position because it assumes (as it must) that everything evolved. To borrow an analogy from statistics, there can be no null hypotheses in evolutionary psychology (i.e., “did not evolve” is impossible), only selection between models, which is the case made in Ketelaar and Ellis paper cited above, because, by hypothesis, every human trait evolved to protect the species (even if it doesn’t; e.g., maladaptations).
Yet Al-Shawaf claims that decisive experiments are conducted in EP all the time, citing a bunch about disease and disgust. Maybe I missed one, but I didn’t see any of the testing of competing hypotheses that Ketelaar and Ellis suggested. Instead, I saw, as the Al-Shawaf claimed, physics-like experiments. And when I asked him about competing hypothesis—e.g., that disgust as disease was learned—I was informed that learned behaviour is evolved behaviour. No doubt. In fact, we could substitute the EP hypothesis with a learned behaviour one like “people learn to be disgusted at disease-bearing things” without affecting the result. After all, the experiment merely showed differential disgust at images of disease. And even though evolution wasn’t mentioned, we’d get a hypothesis supporting the conclusion that disgust evolved to protect us from disease because, again, learning evolved too. So what did we learn from this experiment that we didn’t already know going in? Nothing. We already knew that disgust evolved to protect us because, by hypothesis, everything did.
Wait, what? The failure of verification in EP—or rather its circularity—is more obvious in an absurd example. Suppose our hypothesis is that fear evolved to protect us from insane dwarves. Following the disease-disgust experiment, we juxtapose images of sane-looking and insane-looking dwarves. The predictable result is that respondents will rate the insane-looking dwarves as more fearful than the sane-looking dwarves, confirming the hypothesis that fear evolved to protect us from insane dwarves. Sure, it’s absurd. But what’s the logical difference between this experiment and the one cited above? Nothing other than the one above is superficially more plausible.
If this is not enough to make you question EP, consider what happened when researchers did fail to confirm a beloved EP hypothesis, namely, the link between facial symmetry and disease (which is written up here: https://www.livescience.com/47322-facial-symmetry-sexy-health.html). Despite the rigor of this study and the massive sample, here’s what an EP researcher had to say (quoting from the article):
“Our psychology evolved long before we had modern medicine and public health, so how does this compare in terms of the health environment of nonmodern populations and foraging environments, but also with the range of asymmetry?” Kruger said.
Ancient humans may have had a wider range of ailments, leading to more asymmetry than what exists in humans today, Kruger told Live Science. The new study should be repeated with tribal people who live more like early hunter-gatherers and are subject to some of the same challenges from diseases and parasites, he said.
If decisive experiments mattered in EP, the facial symmetry-disease hypothesis would be dead. But they don’t matter—not because of personal recalcitrance on Kruger’s part—but because EP cannot confirm or disconfirm anything concrete. All you have to do is gin up an evolution-consistent ad hoc reason the hypothesis could still be right and keep going as you were.
An enjoyable and well written article. There is a new theory presented in a book titled Our Human Herds that expands on these ideas.
It proposes that human moral impulses are survival mechanisms.
Just as our senses of sight, smell and sound evolved to help us navigate our physical environment, two distinct social senses evolved to help us succeed in our social environment of people and groups.
These two “social-senses” or two “moral-outlooks” evolved to help us get through the two basic social situations all groups face:
Either THERE IS ENOUGH FOR ALL or THERE IS NOT ENOUGH FOR ALL.
Armed with these two distinct moral outlooks guiding how to feel in each situation we have developed two moral codes that manifest themselves everywhere. In politics we call it “liberal” or “conservative” in economics we refer to them as a tendency toward “socialism” or “capitalism” and even when dealing with matters of the psyche we we divided into “personality” or “character.”
The book introduces this as THE THEORY OF DUAL MORALITY
http://www.ourhumanherds.com/
Ofcourse, the egregious just-so stories of sociologists are perfectly acceptable. It’s worth pointing that double standard out. Sociologists and left leaning people more generally are only critical of “just so” stories that relate to genes and evolution as it pertains to human beings (ironic) but when it comes to ad hoc sociohistorical narratives that support environmental causes/negate evolutionary ones, they accept them blindly. there’s no such criticism of story telling then.
To add:
Just as an example, this bias is why I believe Jared Diamond is so lauded for work that is essentially one big “just so” story, and a poor one at that, but the intellectual mainstream have largely lauded him for this because he tells them what they want to hear. Even most popular evolutionary psychology material is far superior in scientific rigor to Diamonds’ “work” but does not receive the same praise and is criticized to an extent that Diamond is not.
The majority of left leaning people I know accept Diamond’s work uncritically but simultaneously bash Evol Psych for its “just so” explanations.
No doubt slavery and colonialism were bad (although there are many nuances to colonalism that we aren’t able to discuss objectively) but acting like that is a sufficient and complete explanation for present-day inequalities is another common example of an environment-only narrative that is uncritically accepted while we simultaneously hold evolutionary explanations to higher standards.(Ironically by the same people who bash creationists.)
Signed,
A frustrated Liberal
I think this is a mischaracterization of Diamond’s work. To take the example of his latest book, he clearly states that it presents only a hypothesis based on his personal experiences in different countries, which is acknowledged as not a formal study but is chock full of useful information. He frames it as a starting point at which tomatoes should be thrown and generalities treated with skepticism. To say it is only a “just so story” is a misrepresentation. I find integrative narratives like his to be incredibly interesting and valuable. And for his specific topic, I would be highly skeptical that Evol Psych would have all that much to say (and I agree with most of the present article).
i’m not really aiming at him, i’m aiming more at the people who lap up everything he says as gospel but at the same time expect evolutionary psychology explanations to meet the level of a hard science or they dismiss them entirely. It’s the double standard of certain people that irks me.
I have frequently had the experience of offering an evolutionary psych explanation that i am flamed for and expected to clear a hurdle of evidence that nobody else does when offering an enviroment-only hypothesis of equivalent or lesser rigor. those get a free pass and just about any narrative goes providing the causation posited is solely environment while i must setup the equivalent of a physics experiment to satisfy them of an evolutionary explanation, at least and really only when it pertains to humans, of course.
it frustrates me that the burden of proof tends to be unfairly portioned like this with environment-only explanations being privileged when they really should also be expected to carry a burden of proof, at least as high. the guy who writes this article and just about all of them have to face down “just so” dismissals of their work at every turn but Jared Diamond and my old sociology profs get to explicate their poorly evidenced narratives and without such attacks for in my view, are far less rigorous narratives than those offered by evolutionary psychologists.
Fair enough, I get your point (and it seems quite aligned with the article). Thanks for taking the time to reply.
https://en.wikipedia.org/wiki/Tu_quoque – when you’re given a good criticism, you’re expected to learn from it and then use it when appropriate. But when you’re presenting your work, you do have to present evidence for your claims, that’s the point of a presentation. When others present their work, then you can, and should, use the same argument if it is appropriate.
And you can’t possibly mean “all sociologists/left leaning people” or “only sociologists/left leaning people” or even “most sociologists&/left leaning people”, or do you have any evidence that that’s the case other than your personal experience? I get it your frustrated, but you’re frustrated with a specific set of people, there’s no need to make generalizations.
Another explanation for the persistent misunderstanding of evolutionary psychology is that human behaviour is a political football. Many have a vested interest in arguing either for ‘nature or nurture’ and if (as you suggest) the answer is ‘both’ then naturally that will be distorted.
We see this in the problem of mass shootings. One side will latch onto a personal history of mental disability (implicitly innate) while the other side will obsess over cultural conditioning in a prejudiced society. Few commentators are prepared to say that both may have been factors (along with others like stressful life events or the availability of lethal firearms).
Thanks for the interesting discussion and some worthwhile links for later reading.
Thanks for this excellent piece! Thoughtful and well written. Glad to see individual differences discussed.
Wow, way to dance around the topic without mentioning it. Evo-psych enables racists to point at scientific evidence for their racism. Science must never be abused in this way, it is the white man who came up with the idea there is “objective truth” and used it to oppress peoples of color. The Enlightenment’s ontology, rooted in the new science of the 17th century, created a vision of human beings in nature which provided weapons to a new race-based ideology which would have been impossible without the Enlightenment.
The entire idea is that there is no objective truth, only differing points of view, all equally valid. For example, there is no valid genetic basis for human intelligence, there are merely different kinds of intelligence. Native Americans do poorly at intelligence tests designed for whites, but excel at tests designed to measure storytelling intelligence.
Poe’s law strikes again. I have no idea if you’re trying to make a certain stripe of left-wing activists look bad or if you really mean what you write.
You believe that reality is something objective, external, existing in its own right. You also believe that the nature of reality is self-evident. When you delude yourself into thinking that you see something, you assume that everyone else sees the same thing as you. But I tell you, Winston, that reality is not external. Reality exists in the human mind, and nowhere else. Not in the individual mind, which can make mistakes, and in any case soon perishes: only in the mind of the Party, which is collective and immortal. Whatever the Party holds to be the truth, is truth. It is impossible to see reality except by looking through the eyes of the Party. That is the fact that you have got to relearn, Winston.
Heinz – kudos for this excellent parody of PoMo. You should post more – your satiric talents are up there with Titania McGrath!
Great essay. I encounter misconceptions 4 and 6 all the time, and the others occasionally or frequently.
I might take up just-so stories problem later, but I have to point out that mischaracterizing the content of the sources you cite is the easiest way to shoot yourself in the foot. You wrote that “evolutionary hypotheses yield predictions” that “are eminently falsifiable,” with that last phrase linked to a paper by Ketelaar and Ellis entitled “Are Evolutionary Explanations Unfalsifiable? Evolutionary Psychology and the Lakatosian Philosophy of Science.”
Anyone reading your remark and the title might think the Ketelaar and Ellis paper argues that hypotheses in evolutionary psychology are indeed falsifiable. It does not make that case. Ketelaar and Ellis do not answer the question in the title of the paper because they reject Popperian falsification in favour of Lakatos’s approximating model of science. This is explicitly stated in the subsection tellingly called “The Lakatosian Philosophy of Science in Psychology: A Necessary Addendum to Popper’s Method of Falsification” (pp. 2-3). So, no, your source doesn’t show that evolutionary psychology theories are “eminently falsifiable.”
Fair enough! That wasn’t the ideal link. I would respectfully suggest that the argument holds anyway (it doesn’t depend on the link).
Well, you haven’t argued that evo-psych hypotheses are falsifiable. Your argument is that evo-psych yields testable predictions, which is to argue their verifiability, not their falsifiability, and verifiability does not entail falsifiability. The criteria are apples and oranges. The hypothesis that the moon is made of green cheese is verifiable, for example, because a sample of the moon is an empirical test. It is also falsifiable because the result of that test can be decisive in principle—meaning that the test of a prediction deduced from the hypothesis (e.g., Any sample of the moon will be made of 99% green cheese) will unambiguously determine the truth or falsity of the hypothesis. It’s worth noting in this example that it doesn’t matter what the moon turns out to be made of; all that matters is that (1) the moon sample is green cheese or (2) the moon sample is not green cheese.
Now look at the predictions you cited about disgust and disease and ask whether the failure of any one of them—or even all of them—could falsify the hypothesis that “disgust evolved to protect us from disease.” The answer is no. And the main reason is that none of the experiments is decisive. This failure isn’t a peculiarity of this hypothesis, by the way, but a general one for all evo-psych hypotheses. Why? Because every human trait one might isolate evolved—it must be the result of some selection story. Incidentally, the unfasifiability problem is probably the reason Ketelaar and Ellis chose Lakatos over Popper.
But what about verification? Ketelaar and Ellis make competing hypotheses the standard (Lakatosian approximation), but I didn’t see the most obvious competing hypothesis in the first few disgust-disease papers you cited. Nor did you talk about the most obvious competing explanation, namely, learned behaviour. If Ketelaar and Ellis’s account of evo-psych methods were accurate, however, the experiments on disgust and disease should’ve looked at whether evolution or culture explained the behaviour, not whether they could predict (rather obvious) results like people being more disgusted by a towel stained with human excrement than one stained with blue dye. Do children react like that, for example? In my experience (and epidemiological research on disease showing children to be the primary vectors for the flu), I suspect that there’s a strong case to be made that disgust at disease-signs is learned, especially when people (e.g., doctors) can unlearn it.
Add another problem—that one must distinguish adaptations from maladaptations—and one comes to the unfortunate conclusion that evo-psych theories are highly underdetermined by evidence. This is the epistemological problem underlying the just-so stories put down. One can, as Quine put it, defend evo-psych theories come what may. None of this is to deny that evo-psych people are conducting controlled experiments in a scientific way—they are. The problem is that the results of the experiments can’t prove or disprove anything. When it comes down to it, this is the only thing that matters.
The philosophical problems you point out have wide reaching implications for science in general, not just evol psychology.
So my question is – where does that leave us, in your opinion? Do you see it as a problem with falsification as a criterion of good science or does this eliminate evolutionary psychology as a proper science? (and much of science done in general, especially social sciences which in most cases are less rigorous).
Do we eliminate evo psych (and all thes social sciences) as legitimate fields of knowledge or do we demote them in some way but still give them some legitimacy as far as the field’s ability to provide us some kind of knowledge and insight into our world? for instance, calling it a science, but maybe a softer science than say, chemistry. i would say physics but they are having their own philosophical war over this very thing.
More simply, do we eliminate all these fields including all the social sciences and say they can’t provide us any sort of useful knowledge or insights or do we question Popper and adjust our criteria of what counts as science or at least as a legitimate field of knowledge?
sorry, as usual, I write my answers too hastily.
To add:
You have pointed out some reasonable philosophical problems with falsification *and verification*. These have wide reaching implications on science in general, not just this field. So where does that leave us?
Hi X Citoyen, underdetermination of theory by data is a problem for all of science — perhaps a perennial one. It’s not unique to evolutionary psychology (or any specific field).
As for learning, it is not in conflict with evolution. That was misconception #1.
Cheers, Laith
How would the failure of the predictions not falsify the theory? If none of its predictions come true, I would view that as a falsification of the hypothesis. Edward Wilson abandoned his gay uncle hypothesis because it kept getting falsified, unless you wish to posit that it somehow wasn’t. The ovulatory shift hypothesis is also on shaky foundations as late as well and is well on its way to being falsified.
If a theory’s predictions keep coming false, I would say that is grounds to falsify it. I mean on what other grounds would you falsify it? No one experiment is decisive but how many scientific theories are proven or falsified with one experiment?
Stundust,
How would the failure of the predictions not falsify the theory?
By never failing. That’s the point EP predictions. You can always defend the hypothesis. I cited the case of facial symmetry above: The experiments should’ve been decisive, but they weren’t because, as an evo psychologist pointed out, we might have changed since Paleolithic times. Can you think of any EP hypothesis (e.g., Wilson’s) that couldn’t be defended by the all-purpose “we might’ve changed since Paleolithic times” defence? Didn’t think so.
You might have misread Ketelaar and Ellis, which is a perfectly appropriate citation by Laith. Their paper does make the case that evolutionary theories are falsifiable. This should have been clear from the abstract alone: “The charge that evolutionary theories and hypotheses are unfalsifiable is unwarranted and has its roots in a commonly accepted, but mistaken, Popperian view of how science operates.” And on page 2:
“The charge that evolutionary explanations are unfalsifiable centers on two related claims… (2) specific evolutionary models and hypotheses that are drawn from these basic assumptions are said to be untestable. This second charge has taken at least two forms. Either: (2a) Specific evolutionary models and hypotheses are said to
be—in principle—not rejectable on the basis of evidence…” So 2a, according to them, is support for the claim of unfalsifiability of specific hypotheses. Here’s what they say about 2a next:
“(2a) Specific evolutionary models and hypotheses are said to be—in principle—not rejectable on the basis of evidence… We consider the first part of this criticism (2a) to be a nonissue: Scientists using an evolutionary perspective have clearly generated many testable models and hypotheses that can be—and have been—either supported or rejected on the basis of data.”
They refute each of the two claims on which the “its unfalsifiable” arguments are made. The criticism of Popper and reference of Lakatos is an explanation of *why* the claim of unfalsifiability is mistaken.
Lastly, they do not share your view of Popper and Lakatos has binary combatants, two philosophers enter but only one leaves! Their view is that falsification is, of course, useful and important to science but that it isn’t a proper description of how science should or could progress:
“Although Newell’s (1990) argument sounds like a forceful renunciation of the Popperian perspective, it can be treated as the recognition of a necessary caveat to Popper: Although the method of falsification is USEFUL for evaluating the scientific status of specific statements, it is an inappropriate strategy for directly
evaluating the theories that generate such statements.
…Newell (1990) called for psychology to recognize the utility of the Lakatosian philosophy of science as an addendum to Popper, as did Meehl (1978, 1990), because he saw Lakatos’s approximating model as better suited to the task of constructing a unifying metatheory for psychology. (The strict use of Popper’s method of falsification
has been challenged by many philosophers of science as an inaccurate depiction of theory testing in science; see Kuhn, 1977; Lakatos, 1970, 1974; Maxwell, 1972;
Meehl, 1978, 1990; Putnam, 1974.)”
This little history of science lesson is meant to chasten the followers of Gould and Lewontin: psychologists were *never* strict Popperians about research. Popper’s strict falsificationism was contested as inadequate, too simple, and too restrictive from the start.
You are right. But the problem with your remark is that Gould and Lewontin are not Popperians either. They knew very well that historical research must have different epistemological standards than “hard” science. Points 6 and 7 in this article completaly miss the core points of G&L’s critique. 🙂
* completely
Great Article – Although I think you are being charitable with regard to the motivations of those that reflexively use the “Just So Story” objection as a cudgel…