The true origins of autism?
Forget smartphones or vaccines, a new study reveals that neurodivergence is something that evolved millions of years ago. And we likely wouldn't be human without it.
Why are there so many autistic people these days?
That’s a question that gets asked surprisingly often. Well, I get asked it surprisingly often, anyway. But that’s probably inevitable, given my line of work.
Because, as many will point out, you hear a lot more about autism these days than you ever used to. It seems like every third person is being diagnosed as autistic, or ADHD, or some other form of neurodiversity.
It’s not an unreasonable observation, admittedly. I’ve had many friends and acquaintances, my age and above, be formally diagnosed as neurodivergent in recent years. I’m nearing the point where I have more neurodiverse friends than neurotypical, if I’m not there already.
I admit it does make me wonder… is it me? Am I doing this?1.
Obviously that’s not a serious concern. But, you could argue it’s no less unlikely than many more ‘mainstream’ theories as to the cause of increasingly visible autism/neurodivergence.
Is it the ever-improving awareness, constantly-refined assessment methods, greater accommodations in place that allow neurodivergent people to exist, to an extent, without having to mask, at tremendous cost to their wellbeing? No, it’s nothing so prosaic. It’s smartphones! Or vaccines! Or, I don’t know, fluoride in the water?
Confession: I thought I’d made that last one up for comic effect. But no, it’s a thing.
But when you know how the brain actually works, none of these things are particularly convincing. Given how much the standard brain contends with both, internally and externally, while still managing to develop normally, you’d assume it would take more than a screen, or inert pathogen, to knock it off course so profoundly.
And you’d be right. Because autism and neurodiversity are actually a consequence of how the human brain evolved. You could say they’re a feature, not a bug.
That’s, at least, what the findings of a recently published study suggest.
Autism: a particularly human quality
The recent study, from Stanford University, provides arguably the most compelling evidence yet for the view that autism/neurodivergence has been around since the dawn of our species, and we evolved in a way that made it as common as it is.
Admittedly, this has long been my view. I’ve even written about it before, for this blog.
But there’s a difference between indirect, piecemeal evidence, no matter how copious, and clear, direct evidence. Which is what this recent study (potentially) offers.
Full disclosure: this study concerns genetics and molecular biology, and I’m not especially qualified in these disciplines. I can navigate my way around them, sure, but in the manner of someone with a GCSE French navigating their way around southern France2; i.e. don’t rely on me for anything definitive. Indeed, if anyone more relevantly-qualified spots issues or errors with what I’m saying, please do leave corrective comments.
Anyway, the study notes that autism and related manifestations of neurodiversity are uniquely human phenomena. Autism analogues haven’t been found in other primates, or other mammalian species3 thus far. Why, pray, is that? Well…
The main finding of the paper is that DNA analysis of several primate species (and mice) revealed that genes responsible for key neurons and neurological regions (specifically, layer 2/3 intratelencephalic excitatory neurons) diverged in humans, and only humans, millions of years ago, and rapidly evolved distinct properties, properties which seemingly resulted in widespread neurodivergence.
In simpler English; unlike other similar species, the human genome, specifically parts responsible for important brain regions/processes, evolved in ways which meant autism and neurodivergence were not only possible, but relatively likely.
Even more importantly; the data indicates that this wasn’t just some accidental genetic quirk that went uncorrected by evolution. No, the rate of divergence strongly suggests it was positively selected. Meaning, it was an evolutionary advantage.
But, why?
The evolutionary benefits of autism and neurodivergence.
What would be the advantage of neurodivergence in the distant past, when our newly evolved species was trying to establish a foothold? It’s impossible to say for certain. None of us were there, after all.
In fairness, the study doesn’t make any claims about this. It specifically focuses on what the genetic traits linked to autism.
Interestingly, the study reports that genes associated with autism are downregulated in humans. Which would suggest they're not as common/active as in other species. Which would make us… less autistic? But that's now how it works4. The downregulation is what leads to neurodiversity.
It may be that the genes associated with autism etc, are like pillars, holding up the platform that supports neurotypical brain setup. Thanks to our unique genetic profile, human brains have fewer pillars, so our neurotypicality is less stable, more prone to 'wobble' and diverge in interesting ways. And so, autism exists, and is common in humans.
Why would our genes evolve in such a way, though? The study suggests some interesting possibilities.
One is that the genes linked to autism are also play key roles in the neurological regions/processes which give rise to human language. The human brain has many regions for processing and expressing complex spoken language. If the genes responsible for developing these were more ‘flexible’, it may have allowed enhanced development and acquisition of language abilities, a key element of human interaction and society. Autism may be an inherent evolutionary biproduct of this, so it became common.
Another is that the genes in question also play a key role in brain development (many genes play multiple roles and impact multiple processes, especially in the brain). Downregulation of the genes meant young human brains don't develop as fast as our primate peers, as evidenced by the fact that humans have incredibly long childhood/maturing stages.
This is advantageous, because our hefty brains require us to be born 'early', and our complex cognitive abilities take longer to develop. So, slower brain development is vital. Again, autism may well be a an acceptable consequence for such important trait.
However, while the authors are very up front about the limitations of their study (e.g. there's not a vast amount of genetic data in this particular area, so any comparisons and conclusion won't be especially statistically powerful), I’d argue they lean too heavily into the notion that autism/neurodiversity are an unintended consequence of more ‘useful’ evolutionary processes. The possibility that autism is a useful evolutionary trait in its own right is left unmentioned.
But it easily could be.
One risk of tight-knit human tribes, strictly adhering to established roles and hierarchies, is stagnation, as everyone follows familiar routines. But if you've got select people who see and understand the world differently, you've got greater diversity of thought, more potential for innovation, for problem solving etc.
I'm not saying neurodiverse people are responsible for human success and dominance… but I’d confidently say they had a hand in it. Consider all the prominent thinkers and innovators of history who showed blatant signs of neurodiversity, from Alan Turing to Leonardo Da Vinci. Recent studies also suggest the earliest human artworks were the result of autism. And you can certainly see a use for people who are highly attentive to detail and analytical, in a poorly-understood world riddled with threats to survival.
Ultimately, this study provides some of the clearest evidence yet that autism is not the result of screens, or jabs, but of millions of years of evolutionary selection. If people accept this, and understand that neurodivergence is a key feature of who we are, we could make better progress at accommodating and enabling such differences, which would make things better for everyone.
A note of caution.
When writing pieces like this, there’s always a risk that some will, likely with the best intentions, take it to mean I’m saying that autism is uniformly great and should be celebrated. Because we evolved to develop it. What else could I mean?
I can’t say I agree, though. Because it’s a very short step from there to declaring “The only disability is a bad attitude”, or some other inspiration-porn, toxic positivity guff.
Hence I feel compelled to point out that this isn’t how things work. Evolution doesn’t work in absolutes. As long as a trait gives sufficient individuals enough of an advantage to ensure survival of the species and propagation of the genes, that’s usually enough. It doesn’t have to be 100% perfect. It just needs to ‘work’ more often than not.
For instance, the human bipedal stance means we can walk further, and for longer, using less energy. A crucial advantage! But at the cost of numerous back and spine issues.
Our complex immune system allows us to fend off all manner of pathogens and illnesses. And it can also lead to debilitating, even fatal, autoimmune disorders.
And sure, autism and neurodivergence can be very advantageous, or just an alternative way of thinking and being. But it can also manifest in ways that cause problems and hinder normal functioning. because it can, and does, vary tremendously.
Basically, neurodivergence is a part of the human condition. For better or worse. Again, the sooner sufficient people accept that, the better off we’ll all be.
Not exactly related to this post, but check out my latest book for kids, Why Your Parents Are Hung-Up on Your Phone and What To Do About It. Coming up to the one year anniversary of its release!
And I hear a certain bestselling scaremongering pseudo-intellectual has basically ripped it off for his next book, so get the genuine article before he swamps the market. Again.
It’s like how I’m friends with what I’d suspect is a statistically unlikely number of lesbians, for a middle-aged straight man. And the only thing all these women have in common is that they all met me at some point. So… actually, you know what? I’m going to abandon this train of thought before I end up doing lasting damage to my self confidence.
I experienced exactly this scenario as a teenager, so I can confirm this is a valid comparison.
With other species and animal groups, it’s even harder to tell. They’re so cognitively different to us, at fundamental levels. What would a neurodivergent lizard look like? Or shark? Or bumblebee? Even if such things did/do exist, how would we ever align them with our own styles/methods of thinking?
If my reading of things is correct. Which, as stated, it may not be.
You inspired an article of my own, thank you. This was a fabulous rabbit hole to explore!https://open.substack.com/pub/helenatbranchcounselling/p/modern-life-micro-stresses-and-neurodivergent?r=3hzwxf&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
My take on it is that, during all of the time when our evolution was taking place, we lived in little tribes of about a hundred people. Each tribe would have at least one autistic person who would serve as a counterbalance to the chief. We were a second loci of power built around respect for our ability to see differently, and that was tied in with a lot of gender nonconformity in a great many tribal peoples before the Christians exterminated them. The result was that the chief led the way most of the time, but the medicine woman would recognize when the chief was leading the tribe off a cliff, and step in to intervene. Producing greater long term survival for the tribe as a whole.