Script below the fold:
In response to an obnoxiously common attitude that science is all about truth and reality and all those good things, this is the first in a video series that attempts to explain some problems with that pollyannaish idea — that actually science is a philosophy that tries to build a coherent model of how the world works with empirical evidence, but that it is done by human beings who have flaws and biases and who tend to impose unwarranted levels of certainty on certain interpretations, and that in particular we tend to attach greater meaning to conclusions that favor conformity to cultural assumptions on the evidence.
We also have a framework, or lens, through which we view the world, and we tend to take it for granted. For instance, I have scientific training in neurobiology, genetics, development, and evolution, and I’m also an atheist with an ultimately reductionist perspective — there’s nothing but matter, energy, and information in the universe. That means I’m perpetually tempted to just assume phenomena can be distilled down to interactions between atoms, and I definitely am confident and believe that that is true, but what I can’t justify is the assumption that we, as scientists and human beings, KNOW how all those interactions work. We don’t. The one thing we know for sure is that they’ll be far more complex than we expect, and that there will be surprising and unpredicted side effects and causal connections.
Far too many people confuse science, which is a process for investigating reality, with reality itself.
This is quickly going to become a tangled argument because, in addition, our modern culture tends to favor scientific explanations, so it’s really easy to get in a loop. Scientists search for evidence that, for instance, our culture is the superior human culture, and then society turns around and claims that the idea that their culture is superior has now been reinforced by Science, which then increases the incentive for scientists to bolster that bias. And it goes on and on until you’ve got loud nitwits in the public sphere proudly announcing that it’s a scientific fact that Africans have an average IQ of 70.
This is not to argue that flat-earthers and creationists (or “scientific” racists) have valid points, or that science is merely a matter of opinion: they don’t, and it isn’t, and there are levels of certainty, and the age and shape of the earth are not debatable conclusions. But some aspects of science have acquired a kind of epistemic arrogance that has been seized upon by certain deplorable aspects of society as an excuse to make extreme claims of confidence for what are actually unsupportable claims, and are using those claims to complete the loop and propose some ugly changes to our social environment.
I’m going to start off gently, with a topic that probably won’t shock you or trigger raging denunciations from the Status Quo Warriors of YouTube. Let’s talk about a simple phenomenon that tends to get painted with unfortunate levels of genetic determinism.
The instigation for this video was my curiosity about arachnophobia — I seem to totally lack it, and am instead fascinated by spiders, but when I started showing off videos of my current research interest in the lovely Parasteatoda tepidariorum, I got comments and complaints from people who blanched when they saw a mere picture of a spider.
How interesting, I thought. I wonder why people have such deeply different views on something as common as an ordinary resident of our houses. I wanted to look this up — not because I wanted to justify throwing closeup photos of spiders at people who didn’t want to see them, but because I honestly wondered how this kind of phobia could arise. So I turned to the scientific literature and other sources, and tried to find out what the root causes were.
I was not surprised to find some sober and reasonable explanations in the scientific literature, but what was disturbing was how rapidly the explanations drifted into absurd genetic determinism the farther you went from the serious work in neurobiology — oddly, while the scientific literature is rather ambiguous and acknowledges that phobias are a complex phenomenon, as you move into pop psychology magazines, the reported frequency of arachnophobia begins to rise, and you get more articles telling you it is a primordial response in evolution and has a significant genetic component, and by the time you get to the tabloids you’ve got nonsense like “Phobias may be memories passed down in genes from ancestors” and “Humans are hardwired to fear their angular legs and unpredictability”.
The various popular science websites aren’t immune, either. “We Really Are Born With a Natural Fear of Spiders And Snakes, New Study Shows”, says Science Alert. I read the study — no, it doesn’t show that. It’s not a bad bit of research — it shows that a small sample of 6 month old babies show a stronger pupillary response to spiders than to flowers, but it’s being overinterpreted. TechTimes is even worse at describing the same paper: “Researchers Uncover Genetic Roots Of Fear Of Spiders”. No genes were examined in the study. No genetic analysis at all was done. How can you talk about genetics when they didn’t even look at heritability or familial relationships?
Another strategy is to invoke evolution, specifically selection. Spiders are a threat! They’re dangerous! Therefore, it was advantageous to have a strong aversive response to them, and we can assume that Nature has equipped us with an automatic danger avoidance mechanism in arachnophobia. One of my sources even says this:
One prominent theory states that early on in human evolution, spiders posed a threat, so we’ve developed a sort of hair-trigger reaction to them.
Curiously, while it’s called a “prominent theory”, they don’t provide a reference. It is simply assumed that spiders have posed a threat, and that of course natural selection has saved us from it.
One problem with the theory, though, is that spiders are not and have not ever been a serious threat. There are venomous spiders that have the potential to do people harm, but the thing is…they don’t have any interest in biting people. People are not their prey. People sometimes try to harm spiders, sometimes as a byproduct of arachnophobia, which leads to them getting bitten in self-defense, but honestly, they are an inconsequential hazard.
I tried looking into the spider-caused death statistics. One problem is that they’re so rare; you’ll sometimes see the number 6 thrown around…as in, there are about 6 deaths from venomous spiders in the US in a year, but even that falls apart when examined closely. One of the scariest spiders around the US is Latrodectus, the black widow spider. Fear that red hourglass! but there are only 3, count ’em, THREE reports of deaths by black widow envenomation in the entire world medical literature in all of recorded history. None of them have occurred in the US.
Another so-called deadly spider are the South American wandering spiders. How many fatalities have they caused? 10. Only 10 in the entire recorded history of Brazil. Ten is not nothing, and it would be very wise to avoid the risk of being bitten by Phoneutria, but it’s clearly not a danger that should make Brazilians tremble in fear. That Bolsonaro primate running the country is far scarier and will end up killing far more people.
The Australian Redback is a relative of the black widow, and as we all know, everything in Australia is trying to kill you, so I was a little surprised to find this headline from 2016: “Young man is first to die from spider bite in Australia for 37 years”. The poor man actually died from an infected spider bite, not the venom, so there is that: a general aversion to biting arthropods is a useful property. They hurt, they can lead to infection, and even tiny creatures can cause deadly infections. But mosquitos kill a million people every year. In the general category of entomophobia, it seems strange to single out one group, the spiders, with a specific label of arachnophobia, especially when you consider that spiders kill mosquitos which kill millions, or to think that we’ve evolved a genetically determined response to a specific organism in the absence of any selective advantage.
Being bad at risk assessment is not a sound foundation for an adaptive explanation.
I mean, we have strong evidence that leopards were significant predators of our hominin ancestors, with traces of big cats gnawing on their skulls. We know that even today, leopards are dangerous to baboon and chimpanzee troops. Shouldn’t we, by that logic, have ailurophobia burned into our genome? But no, instead we’ve become raging ailurophiles. No one has ever, as far as I know, sent a worried and regretful email to a website owner asking them to please stop showing so many pictures of cats, because it makes them queasy. Ailurophobia seems to fade easily into ailurophilia, which ought to tell you something about the malleable and experiential nature of these things that some people would like you to believe are hardwired by an inbuilt ancestral and genetic memory.
Does this imply that there is no genetic foundation for phobias, or that I believe people are blank slates or infinitely malleable, that common caricature of people who don’t accept the omnipotence of genes? No, not at all. There is good evidence that there are genetic predispositions to some kinds of phobias, but that they’re the product of both genetic factors and experience, and also, that they’re not quite as specific as some have argued: that there may be a general predisposition to animal phobias, for instance, but that fears of specific animals are shaped by personal histories. So someone might inherit a tendency to shy away from animals in general, but could have had a happy childhood with beloved pets and be totally into working at the humane society; someone else could totally lack any genetic bias to fear animals, but after a single intense traumatic experience with bats, he grows up to be Batman.
Here, for instance, are the results of a twin study done on over 4,000 twin pairs in Virginia to assess the heritability and environmental influences on various phobias. I know, it’s a complicated tangle of numbers, but all you have to know is that BOTH genetics and environmental effects are important in every one of the phobias. They went further and looked for correlations between phobias — for example, is there just one general heritable “phobia proneness” trait, or is each one of these independent and specifically regulated? — and found that neither extreme is true. They found four rough clusters of traits that imply perhaps four general causes; arachnophobia is part of a correlated package that includes other animal phobias, like fear of bugs, mice, and bats, and also, interestingly, includes social/agoraphobic fears. We’re all just animals, I guess.
Again, remember that the causes are multifactorial. You could have a genetic bias to like animals and social situations, and still have been conditioned to fear spiders.
There’s another level to this story — many levels, in fact — and that is the difficulty of translating genetic information into the organization of the nervous system. The genome is most definitely not a blueprint. It does not specify, for instance, the morphology of brain nuclei. There is no map of the connectivity of the brain somewhere in the genome. Rather, the genes establish a pattern of potential responses of cells to environmental stimuli, and the final pattern emerges as a consequence of mostly roughly predictable interactions between genes, cells, and the environment.
I’m always stopped cold at statements about how something as specific as recognition and fear of spiders can be encoded in the genome — it’s challenging enough to see how a network of genes can generate the rough outlines of a brain, setting up reward and fear nuclei and pathways, without proposing that a search image of a specific kind of organism can be propagated through the complex and mostly indirect series of cellular interactions that end in the result of clusters of cells and pathways.
Fortunately, neurobiology doesn’t make such claims. Rather, the models for phobias involve development of a common neurological substrate for fear processing in the brain — substrates like the basolateral amygdala, connections to the locus coeruleus and the nucleus of the solitary tract, and generating and receiving endocrine signals. The brain builds complex circuits that interact to create a general property we call “fear” (we could speculate endlessly about what “fear” means to an organism), and we could imagine that there is some degree of variability in the sensitivity of these circuits that lead to individual variation.
The consensus is that the specific details of a phobia are fine-tuned by experience. There isn’t a specific spider-phobia, but there may be a general predisposition in some individuals to have, for instance, a disgust response to contamination, small animals, vermin, etc., that can be shaped by history and events in an individual’s life.
There is a non-experiential, innate fear that is the product of common neuronal circuitry found in essentially all human beings. There is some degree of variation in this circuitry: some individuals will be more or less sensitive to activation of this network, and others will vary in how readily they habituate to fear stimuli. There is a normal and healthy level of function: sure, you should be hesitant to handle a spider or a creature unfamiliar to you; that’s what this circuitry is for. There are also levels of dysfunction. Failure of this network can lead to a non-adaptive embrace of dangerous novelty; hyperactivation can lead to self-destructive excessive reactions to relatively harmless stimuli, like arachnophobia or PTSD.
Most fears, and the degree of our responses to them, are experiential — they involve modulation of the common fear circuits by our experiences and history. But they are no less real for that. We have plastic brains that respond to our environment and generate physical changes in our nervous systems that are just as significant and just as genuine as the wiring we’re born with. I was not born loving my wife and children; I was born with the capacity to love, and who and how I learned to love certain individuals was constructed. That doesn’t make them less real.
You can no more tell someone that their fear of spiders is an epiphenomenon, something that is generated by their experience, and therefore inconsequential, than you can tell me my love for my kids is epiphenomenological and can be easily over-ridden. Experience is real. Your feelings are valid. Whether they’re hardwired or learned is irrelevant to their significance to the individual. Science doesn’t and shouldn’t favor one or the other, especially since the lessons of genetics and neurobiology and development have been clear that genes and environment are tangled in a feedback loop that makes it impossible to dissociate one from the other.
It’s ironic that the people who are paying the loudest lip service to a reductionist version of science fail to recognize how much of their bias is emotional.
“Facts don’t care about your feelings”
It’s true, they don’t. What is not being taken into account is that feelings are also facts that have to be addressed. Feelings are physiological. They’re part of the equation, and maybe the biggest part — there’s less genetic variation between people than there is cultural and personal, yet somehow we’ve ended up in a situation where the primacy of a narrow (and conclusively false) interpretation of human nature is labeled “scientific”, while the richer, deeper, more complex knowledge of humanity that has been assembled by biologists, psychologists, sociologists, and anthropologists is dismissed as politically and ideologically motivated “feelings” by an assortment of science denialists and anti-science propagandists.
This is what I find fascinating. In popular culture, there’s a kind of general drift towards claiming genetic determinism as a scientific fact. We shift from an observable fact — that some people do have a genuine fear of spiders — to an unsupported opinion — that arachnophobia is a genetic condition — and ignore all the science that says it’s a product of experience shaping a general neuronal substrate to favor a harder version of the story that privileges the notion that it’s a genetic trait.
Why? I have a couple of potential explanations.
One is that science has become the undeniable authority on reality — it’s the new “goddidit”. You don’t have to actually know any science to be able to use the claim that “Science says…” to justify your opinion, just as you never needed to know the actual opinion of a deity to be able to claim he supports you. It’s a handy shorthand that I’m seeing a lot of far-right, alt-right, and centrist science abusers throw around. It’s particularly amazing how they can tell me that, for instance, because I reject the nonsense of pseudo-scientific excuses for racism, I must therefore be a creationist.
Second is that there is a twisted idea of responsibility here. You can’t help what you’re born with, but if you have an acquired disability, well, that’s your fault, and you’re fair game for discrimination. You’re afraid of spiders? Too bad. Here’s a bucket of them, get over it.
I’ve witnessed people mocking others for PTSD…people with no qualifications in psychology or medicine, with distorted ideas about what PTSD is or its causes, and who treat it as a sign of weakness. Acquired disorders are a sign that you are inherently flawed, that you are somehow inferior. That you are damaged by nature, rather than that you’ve been overloaded with damaging environmental inputs.
Third, there is a sense of self-justification. I am well-off, I’m not being discriminated against, the system is working well for me — while for someone else, they are poor, they are suffering, the odds are stacked against them. Which is better for my self-esteem? To claim that it must be because my genes are intrinsically superior while their genes are inferior, or to argue that both of us are in our respective positions because of fundamental biases in our environments? It’s especially troubling when we note that those environments are perpetuated by individuals with self-interest in preserving the status quo — it’s not a difference in genetics, it’s that my privilege is helping to produce your disentitlement.
That’s our situation. The media, politics, and popular opinion are overrun with invalid, absolutist notions of the omnipotence of genetic explanations. All I can do is try to explain why they’re wrong.
Simplicity and certainty are for Nazis. Complexity and nuance are for Lefties. And scientists.
Next in this series, I’ll try to explain the confusion between alleles and traits…a confusion that scientists have contributed to repeatedly for the last hundred years.
A few references: