The incredible part about that detail would be that in any other animal much of Schizophrenia's symptoms would be subclinical, in that language and socialization expresses most of Schizophrenia's detriments.
The paper is really about emergence and transmission of the disorder, and not so much about why humans find faults in those afflicted by it. But consider solitary animals, or apex predators. That they'd be schizophrenic, and construct distorted understandings of the world around them probably wouldn't matter, as long as they manage to hunt for food and produce offspring. No one would care about what a bear thinks of the origin of the universe, or how realistic its outlook of its own future is.
I realize that Schizophrenia has other debilitating effects, but it also affects people in varying degrees.
I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential:
Now that's a very scary chart if you start to project that curve into the future.
Here's another one. Not saying this is the cause, but it is a cause for concern. We have many similar patterns of environmental factors increasing with autism prevalence, which makes the likelihood of it being environmental stronger than something else.
For example it took a long time to figure out that lead in gasoline could lead to cognitive decline. BPA and phtalates is another recent discovery, which cause hormone distruption.
What else do we have today that is yet to be figured out, and what is the likelihood that we have something similar brewing that we do not yet know about.
Correlation != Causation and not every scientist is an expert on Autism/Genetics/Biology.
"Even disregarding the sloppy mathematics, the claim's very basis (that glyphosate is the cause of a perceived increase in autism) is unsupported. No mention was made of how glyphosate was isolated and shown to be a cause (or even a factor) in some or any cases of autism in the article. No autism spikes near agricultural facilities were described, nor was any definitive causative link at all cited by the article (and presumably, Seneff) to back up the purported link between glyphosate and autism rates anywhere other than the imaginations of those making the claim. The single link of merit made within the article (to a USDA report) made absolutely no mention of autism at all but was misleadingly arranged to suggest a connection.
What the claim seemed to hinge on largely was a correlation/causation fallacy: Because [unclear activity involving glyphosate] occurred, a corresponding rise in autism diagnoses must be due to that unspecified issue with glyphosate. Claims of a similar nature have been dispelled with graphs like the following that show how difficult (or simple) it is to "prove" any one cause correlates with any one effect:"
It doesn't need to be one or the other. Genetics can predispose somebody to be more vulnerable to certain environmental factors. They will not show any symptoms unless those environmental factors are present, but there's still genetics involved.
And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.
There are a lot of potential candidates... too many to be honest, and a lot of them are related to basic economic activities. History shows that environmental issues driven by economics aren't solved until an alternative comes along and is adopted; the problems of dead horses and horse dung in NYC streets were solved by... the automobile.
I'm put in mind of the recent paper posted on HN regarding magnetic nanoparticles being found in human brains. Unrelated to autism (probably) is the increasing study of prions and in general, maladaptive protein synthesis. What isn't known about these issues could fill volumes.
My cousin had debilitating autism that was greatly diminished by removing wheat germ from his diet, so I partially buy the environmental take, but on the other hand it is a disease that is correlated with parental IQ, where a higher IQ leads to more likely incidence of autism. I don't think it's a coincidence that the rise of co-sexed secondary education and finer grained sorting with institutions like Harvard and MIT getting an even more concentrated amount of intelligent people.
Since this thread is about evolution, we might even say that the evolutionary pressures we currently face in the developed world actually favor mild variants of ASD.
It might be because some ASD traits help people become more successful in the information economy. Asperger's people often thrive in well-paid occupations such as programming and data analysis where spontaneous social interaction is widely acknowledged to hurt productivity.
Or it might just be a side effect of a society that places a lot of emphasis on intelligence, making it more likely for a person with high IQ to seek a mate with similarly high IQ. The more smart people "inbreed" among themselves, the more ASD cases we will naturally see.
In either case, since evolution is whack-a-mole, this will lead to not only mild ASD but also more cases of severe autism if they are caused by the same set of genes.
But it does ensure your child/ren have access to medical professionals, which causes what the medical community as a whole to see an increase in cases.
I have not seen any evidence that Asperger Syndrome or mild autism leads to well-paid occupations. For sure, there is some anecdotal evidence (which I find unconvincing), but I haven't come across anything more solid, like a research paper or study. If you've seen something along those lines, please post a link.
I do believe that children with Asperger Syndrome often see the symptoms grow less severe as they age. Perhaps with lots of hard work and a good support structure, some of them people grow to enjoy above average success. It seems entirely unreasonable (and to my mind somewhat cruel) to credit this success to Asperger Syndrome itself.
Even Asperger thought that his patient/students had unusual gifts as well as issues. In an attempt to keep the then-new Nazi regime from closing down his school (and later, eliminating "defective" children), he suggested they might make excellent codebreakers. Steve Silberman covers that well later in this audio interview with Terry Gross, and presumably in his book as well:
What appears to be Aspergers now is very similar to spending lots of time on the Internet and then trying to interact socially afterwards. It's quite difficult to appear neuro-typical after a surfing session, and for today's kids, Aspergers is the 'New Normal'. Aspergers was even taken off the DSM-5: http://www.slate.com/articles/health_and_science/medical_exa...
aspergers was lumped into autism, it wasn't made non-diagnosable. Previously the criteria for aspergers were the same as autism but without delayed language development. Now they decided that distinction wasn't worth singling out with a special diagnosis so it's considered autism regardless of language delay. Those who had aspergers are now considered to simply have autism.
In a child with autism, pain becomes debilitating because they can't communicate or cope with pain well. That doesn't mean an allergy or intolerance causes autism, however.
An allergy or intolerance is much worse when it make your nonverbal child irritable and violent, then when it makes your verbal child say "mom, my tummy hurts bad" after you serve pizza.
Really? Did they do any kind of blood tests with and without wheat germ in his diet? It would be interesting to know what exactly was causing that response. That doesn't really sound like a normal allergic reaction.
> I don't quite buy that autism will be shown to be genetic. I think it's an environmental factor. The rate of increase in autism is pretty much exponential:
You're confusing increase in diagnosis versus increase in autism. This confusion is the whole basis of the "autism epidemic" claim.
Its also discussed here on Fresh Air by the author of a book on Autism called Neurotribes.
" But because no one really explained to parents exactly what had happened - that the diagnosis had been completely rewritten - that, you know, autism by the end of the 1980s and the early 1990s was not your grandfather's autism, you could say. It was much more broadly defined because no one ever explained to the lay public what had happened with the diagnosis. When the numbers started going up, parents very understandably became very alarmed. And the media was sort of blindsided by the sudden spike in diagnoses."
When the autism diagnostic criteria were broadened in the DSM, the people making that change predicted that we would see this rise in diagnostic rates. That was the intent, to help a broader range of people. It's played out slowly as clinicians and schools were retrained. There's also been an increasing incentive to diagnose as autism in addition to intellectual disability when possible, because insurance companies and schools will do a lot more if it's labeled autism.
So we've seen that shift. The diagnostic criteria changed a lot, not just a little, over time.
By coincidence, Wakefield launched his fraudulent crap about vaccines a few years after the criteria were broadened, and that became the popular explanation rather than the fact that the criteria changed. Belief in his BS is perhaps fading but it's still around.
The "epidemic" was predicted and an intentional outcome of the DSM criteria change, though.
If you hang out with a bunch of families with autistic kids, it's very obviously inherited in a large fraction of cases, because the kids are so much like their parents.
Another large fraction is likely genetic in the sense of "de novo" mutation, rather than inherited genes. There's likely also a group of environmental cases, mostly prenatal environmental factors.
Because social function depends on many coordinated aspects of human cognition, any condition that has a fairly global effect on the brain can create traits meeting the autism diagnostic criteria. The criteria are very broad, with many different ways to meet them.
It's important to realize that autism is a broad category, not a single condition, and no proposed single gene or environmental factor ever seems to relate to more than a few percent of cases.
https://intellectualizing.net/2013/12/17/book-rethinking-aut...
Some of those causes could well be new to the modern world, but the changing diagnostic criteria do explain most of the expansion in diagnoses already, so there isn't a lot of evidence that we need to be looking for something novel to explain the increased diagnoses.
Can you give more details on the "some of them are obviously inherited, because the kids are so much like the parents" part? Kids everywhere are so much like their parents, so the reasoning, as written, is nonsense.
If it's that, without finer detail, it's also a weak argument. I behave like my mother in many things; doesn't mean I was genetically predisposed to, as plenty of behavior is acquired from the parents.
If you're saying it could be the autistic behavior is learned rather than genetic, then I agree, you'd need a twin study to rule that out conclusively. However, when people say "the autism epidemic is environmental" they usually mean vaccines or chemicals or something, not "learned from the parents."
Despite the quantity of autism research, most of it is quite bad and not that helpful on questions like this.
autism isn't adult-acquired though (literally by definition, DSM specifies that it must be present in childhood). So you'd need parent and child to share environmental factors during their respective infancies.
"Inherited" can mean "genetic" or some other method of parent-child transmission (like learning)
"Environmental" can include "parenting", but in this case the distinction is between "got it somehow from autistic-leaning parents" vs got from something else.
Also, the claim that autism might be somehow learned from parents is extraordinary and not widely claimed or supported by existing evidence. It was a discredited theory of the past though, that "cold" parenting created austism.
Families with one autistic child do have an increased risk of having a second child with the disorder.
There are some evidence that hints to genetic factors. For example, we know that boys are at much higher risk than girls, but we don't know why. Similarly, we know that older parents are more likely to have autistic children—but again, we don't know why.
>>This could just as well apply to environmental factors though, siblings probably share those.
That's correct, but looking at concordance rates between monozygotic (identical) and dizygotic (fraternal) twins demonstrates that there is at least a partial genetic connection.
Identical twins share the diagnosis in 77% of cases, while fraternal twins only share the diagnosis in 31% of cases.[1] Given that identical twins share more genetic material, the conclusion is that autism has a genetic component to its incidence.
That said, most research on the subject, including the paper I'm citing, establishes that there is most likely a dual nature-nurture component. In particular, this study was conducted on twins within the same household, so the genetic component would have been augmented by shared environmental factors.
Kids often share autistic traits with their parents. The parents are either diagnosable themselves or very nearly so.
My son is the third or fourth generation to be likely-diagnosable, for example.
Currently-middle-aged parents without intellectual disability had almost zero chance of being diagnosed as children, because when we were kids autism was defined such that you usually had to be nonverbal or intellectually disabled to qualify.
A very commonly-reported experience is for parents to be diagnosed after their children are diagnosed.
To clarify, I'm not trying to argue definitively that these traits are all genetic vs. acquired by watching one's parents. Perhaps it's some mix, though mostly-genetic seems likely to me. I _am_ trying to say that often the traits run in families, which argues against external causes such as vaccines and chemicals.
I'm not sure if more people with the recessive genes procreate now vs in previous eras, in total; I suspect that more couples that carry autism-related genes are procreating with each other, due to increased prevalence of educational and intelligence-based assortive mating.
I disagree, I find it intuitive that autism is genetic. View autism as a genetically induced alternate brain development. Usually it doesn't pan out, but sometimes it leads to innovation that wouldn't otherwise be possible. This leads to a survival advantage for a given subpopulation, which is sufficient for natural selection.
He addresses that a fair bit, mentioning that autism is one of the most heritable conditions, and talking a lot about the history of the diagnosis and how it was artificially narrow for a long time.
Personally, my bet is that we'll come to see a lot of autism diagnosis as part of a broader pattern of medicalization of deviance from the norm. And that even the forms we eventually decide are harmful have for nerds the same relationship that sickle-cell anemia does to malaria resistance: a trait that is useful in small doses but can be harmful in large ones.
If there is an actual increase, I'd bet on it being due to stronger assortative mating that has come as mate choice has less to do with geographic factors and more with education and workplace.
>>When are we going to finally ditch the idea that heritable==genetic?
Well, considering the fact that "heritability" is a measure of how much of a given phenotype's expression is due to genetic variation, probably not soon. "Heritable" is not a word used to refer to environmental factors such as parental care and upbringing. In studies on heritability of specific traits, these environmental factors are used as classifications for broader observations of genetic variations (for example, in twin studies, was twin pair A raised in the same household like pair B?).
Going back to autism specifically, the Simons Foundation Autism Research Initiative identified a single genetic mutation that accounted for 25% of diagnoses in their Simplex Collection[1], while the other 75% were impacted by 200-400 different genes. This data is available online as of 2016[2], though some analyses may be paywalled.
Well, it would have to come after we start. I think you're boxing strawmen in your head. In the rest of the world the debate between nature and nuture has been vigorously raging for decades and there isn't a "winner".
The article says 1-5% of the ASD cases they looked at were related to the "HARs" (human-accelerated regions). The most important thing to understand about autism is that it isn't a single condition, but an umbrella category with a bunch of conditions grouped into it.
Once we understand that autism isn't a single condition, a lot of the ways the public (and researchers) talk about autism turn out to be kinda nonsense.
It sounds as though you are speaking from the standpoint that genes mutate at random in all and any "directions" (net). However, non-successful genes are eliminated, so in the effective sense it is (gross). The direction of evolution is towards being "more suitable" for a particular environment.
dragonwriter is right in general sense. We can evaluate it, though, from our own perspective. It's a step forward in terms of intelligence and stability in world. It's a giant leap backward in terms of success or happiness in a world of non-autistic people. Evolution would also consider it a negative in that autistics get laid and reproduce less than non-autistics. They also are more likely to loose in competition in corporations, battlefields, and jungles. So, it's a net loss overall for evolution's main function but autistics persist for one reason or another.
These comments are simply unbelievable. Autism is not a super power. Visit families with meaningfully autistic children and come back and tell me if you think it is a "step forward" in "intelligence and stability". These children will need to be institutionalized as adults.
My guess is that the mutations are retained as variation in the population because having some small subset of them probably results in divergent thinking which can increase overall group survival. Autistic spectrum disorder individuals result from having too many of these mutations, such that neural activity patterns find a stable equilibrium outside of "normal" (think strange attractors in system dynamics).
A reasonable theory, but as a minor note most evolutionary biologists wouldn't focus on group survival. Group selection remains controversial.
But your point still stands, and has clear parallels in other cases, like sickle-cell anemia: one copy of the gene is helpful, so it remains in the population, but two copies is harmful, so its spread is limited.
I'm not an evolutionary biologist, but this article (https://en.wikipedia.org/wiki/Evolutionary_game_theory) mentions Hamilton's rule: A given altristic gene will propogate if "the genetic relatedness of the altruistic donor exceeds the cost-benefit ratio of the altruistic act itself". Is this not widely agreed upon?
I'm not sure why you're anthropomorphising evolution. It's a process, not even a thing. It's a consequence of interacting environmental conditions, and it doesn't "care" at all in any sense of the word. No more than point-charges "care" about electromagnetism.
I went the other way with it: high-functioning autism is a component of more-evolved humans. The autistics are more rational, often less selfish in my anecdotal experience, and cause almost no harm to others vs baseline. A world full of them would've largely eliminated famine, pollution, war, violent crime. It would be a fraction of what we see. Further, autistics and introverts are often behind many great advances that push progress of our species forward. That would increase greatly.
So, I've always thought of us as the next thing after homo sapiens. Jokingly call it Neosapiens from a cartoon as it was a cool name. Not likely to actually happen but a nice example of how the world might have been better. My ideal one, though, preserves the different types of people with two modifications: built-in mechanism where causing harm to others makes individual experience personal pain; built-in need to connect outside local sphere to reduce isolationism. These two would keep world more interesting than the safe, autistic one while also eliminating many problems. Just two, small changes in the brain.
OTOH, a world full of people with autism might never be able to come together and build large group projects. Autism might work well for creating in the computer+Internet age (but I have doubts that non-autism traits are totally unnecessary), but much less likely to work in lower-tech society.
"OTOH, a world full of people with autism might never be able to come together and build large group projects. "
This was a problem for the Autreat conference. It was made by autistics for autistics. The coordination required to create it was a big problem. I wonder if things would get better if they were the norm. I'm not sure.
Personally, I am not big on better/worse, but just different. E.g., we could look at white people as a weird mutation of true humans, one shockingly prone to skin cancer. Of course, as a white person, I'd rather see myself as an equally valid kind of human.
For a while I've been wondering what the DSM would look like if non-neurotypical people were in the majority. If we had a diganostic category for what we now call "normal" levels of sociality, selfishness, manipulation, violence, etc.
"For a while I've been wondering what the DSM would look like if non-neurotypical people were in the majority. If we had a diganostic category for what we now call "normal" levels of sociality, selfishness, manipulation, violence, etc."
Interestingly, I think a good chunk of the diagnosis would be the autistic equivalent of what normal people call psychopaths. They'd be seen as irrational and dangerous, esp in groups.
There's no such thing as being more evolved. More fit, maybe. We're all as evolved as each other.
Otherwise you end up having to debate whether people with lactose tolerance are more evolved than people without, and so on. It gets messy.
Also, the history of eugenics. Autistic people have been sterilized and institutionalized, really quite recently. So I'm allergic to talk about people being more or less evolved.
Why do you have to be something different, the next thing after? Other highly coordinated organisms like ants, bees and termites have evolved morphologically distinct developmental paths. Couldn't autistics just be in a sense extreme examples of a subtype of human that serves the purpose of disrupting group-think and introducing new ideas into the culture?
" Couldn't autistics just be in a sense extreme examples of a subtype of human that serves the purpose of disrupting group-think and introducing new ideas into the culture?"
There have been instances of biological twins where one winds up with autism and another doesn't. So to the extent that autism has a genetic component - it is just that - a component.
That does support non-genetic factors to some extent, but the existence of such twins matters less than their frequency, because twins don't always have identical DNA (mutations can occur after they separate).
Also, even with identical DNA, that doesn't mean the twins will be exactly identical: if things like fingerprints are only very similar instead of exactly matching, then there's reason to think that the fine brain structure can vary as well -- perhaps enough to straddle sides of a disorder.
So in addition to twin frequency, it would be worth analyzing twin spread: what is the variation in the behavior of twins (in the background), and is the spread in autistic/non-autistic twin pairs statistically similar, ie, are we just selecting for normal, expected variation that happens to fall close to a boundary?
If autism is caused by an individual mutation (not alredy present in the parent genome) it would be amazing that the mutation is so common, but not currently of a known form (like trisomy).
It could be that there are many genes and many mutations possible to cause it, which means two people with autism would almost certainly not share the same mutation. This would make it quite difficult to work out what the mutations are.
(There is one mutation that causes something like autism, fragile-X)
After spending some time with an individual that has autism, I feel like there's an underlying process to 'normal' cognition that spans a gamut from Schizophrenia to Autism. A shaky metaphor to the neurology might be how equivalent logic circuits can be made from corollary gates. It's as if one condition skews toward signal powered gates vs source powered gates. I.e. more concrete vs 'out there'... Just a quick thought.
(Forgot to explicitly say, the failure modes are different: an inactivation that inhibits gracefully (simply forgetting) vs activation independent of actual signal (spurious thought). False negatives vs false positives.)
> Chimps are social creatures, but they’re different from humans. They don’t live in compact cities of a million people. That requires extraordinary social behavior.”
I don't think cities are a result of social behavior, it's more the result of economic behavior. Cities are clusters of box apartments, which don't really demonstrate social behavior.
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[ 2.9 ms ] story [ 164 ms ] threadThe paper is really about emergence and transmission of the disorder, and not so much about why humans find faults in those afflicted by it. But consider solitary animals, or apex predators. That they'd be schizophrenic, and construct distorted understandings of the world around them probably wouldn't matter, as long as they manage to hunt for food and produce offspring. No one would care about what a bear thinks of the origin of the universe, or how realistic its outlook of its own future is.
I realize that Schizophrenia has other debilitating effects, but it also affects people in varying degrees.
https://en.wikipedia.org/wiki/Amish_anomaly
Food ? Environment ?
http://www.nature.com/news/2011/111102/full/479022a/box/1.ht...
Now that's a very scary chart if you start to project that curve into the future.
Here's another one. Not saying this is the cause, but it is a cause for concern. We have many similar patterns of environmental factors increasing with autism prevalence, which makes the likelihood of it being environmental stronger than something else.
http://images.medicaldaily.com/sites/medicaldaily.com/files/...
For example it took a long time to figure out that lead in gasoline could lead to cognitive decline. BPA and phtalates is another recent discovery, which cause hormone distruption.
What else do we have today that is yet to be figured out, and what is the likelihood that we have something similar brewing that we do not yet know about.
http://www.snopes.com/medical/toxins/glyphosate.asp
Correlation != Causation and not every scientist is an expert on Autism/Genetics/Biology.
"Even disregarding the sloppy mathematics, the claim's very basis (that glyphosate is the cause of a perceived increase in autism) is unsupported. No mention was made of how glyphosate was isolated and shown to be a cause (or even a factor) in some or any cases of autism in the article. No autism spikes near agricultural facilities were described, nor was any definitive causative link at all cited by the article (and presumably, Seneff) to back up the purported link between glyphosate and autism rates anywhere other than the imaginations of those making the claim. The single link of merit made within the article (to a USDA report) made absolutely no mention of autism at all but was misleadingly arranged to suggest a connection.
What the claim seemed to hinge on largely was a correlation/causation fallacy: Because [unclear activity involving glyphosate] occurred, a corresponding rise in autism diagnoses must be due to that unspecified issue with glyphosate. Claims of a similar nature have been dispelled with graphs like the following that show how difficult (or simple) it is to "prove" any one cause correlates with any one effect:"
And of course there's this whole field called epigenetics that studies how the same genes can be expressed differently based on environmental factors.
I'm put in mind of the recent paper posted on HN regarding magnetic nanoparticles being found in human brains. Unrelated to autism (probably) is the increasing study of prions and in general, maladaptive protein synthesis. What isn't known about these issues could fill volumes.
It might be because some ASD traits help people become more successful in the information economy. Asperger's people often thrive in well-paid occupations such as programming and data analysis where spontaneous social interaction is widely acknowledged to hurt productivity.
Or it might just be a side effect of a society that places a lot of emphasis on intelligence, making it more likely for a person with high IQ to seek a mate with similarly high IQ. The more smart people "inbreed" among themselves, the more ASD cases we will naturally see.
In either case, since evolution is whack-a-mole, this will lead to not only mild ASD but also more cases of severe autism if they are caused by the same set of genes.
I do believe that children with Asperger Syndrome often see the symptoms grow less severe as they age. Perhaps with lots of hard work and a good support structure, some of them people grow to enjoy above average success. It seems entirely unreasonable (and to my mind somewhat cruel) to credit this success to Asperger Syndrome itself.
https://en.wikipedia.org/wiki/Asperger_syndrome
http://www.npr.org/sections/health-shots/2015/09/02/43674237...
An allergy or intolerance is much worse when it make your nonverbal child irritable and violent, then when it makes your verbal child say "mom, my tummy hurts bad" after you serve pizza.
You're confusing increase in diagnosis versus increase in autism. This confusion is the whole basis of the "autism epidemic" claim.
"Shifting diagnoses and heightened awareness explain only part of the apparent rise in autism. Scientists are struggling to explain the rest."
http://www.nature.com/news/2011/111102/full/479022a.html
http://www.forbes.com/sites/tarahaelle/2015/01/05/majority-o...
Its also discussed here on Fresh Air by the author of a book on Autism called Neurotribes.
" But because no one really explained to parents exactly what had happened - that the diagnosis had been completely rewritten - that, you know, autism by the end of the 1980s and the early 1990s was not your grandfather's autism, you could say. It was much more broadly defined because no one ever explained to the lay public what had happened with the diagnosis. When the numbers started going up, parents very understandably became very alarmed. And the media was sort of blindsided by the sudden spike in diagnoses."
http://www.npr.org/2016/09/09/493148713/neurotribes-examines...
So we've seen that shift. The diagnostic criteria changed a lot, not just a little, over time.
By coincidence, Wakefield launched his fraudulent crap about vaccines a few years after the criteria were broadened, and that became the popular explanation rather than the fact that the criteria changed. Belief in his BS is perhaps fading but it's still around.
The "epidemic" was predicted and an intentional outcome of the DSM criteria change, though.
If you hang out with a bunch of families with autistic kids, it's very obviously inherited in a large fraction of cases, because the kids are so much like their parents.
Another large fraction is likely genetic in the sense of "de novo" mutation, rather than inherited genes. There's likely also a group of environmental cases, mostly prenatal environmental factors.
Because social function depends on many coordinated aspects of human cognition, any condition that has a fairly global effect on the brain can create traits meeting the autism diagnostic criteria. The criteria are very broad, with many different ways to meet them.
It's important to realize that autism is a broad category, not a single condition, and no proposed single gene or environmental factor ever seems to relate to more than a few percent of cases. https://intellectualizing.net/2013/12/17/book-rethinking-aut...
Some of those causes could well be new to the modern world, but the changing diagnostic criteria do explain most of the expansion in diagnoses already, so there isn't a lot of evidence that we need to be looking for something novel to explain the increased diagnoses.
The implication seems to be that the parents also exhibit traits of the autism spectrum, so it's hardly surprising that their kids would do the same.
Despite the quantity of autism research, most of it is quite bad and not that helpful on questions like this.
"Environmental" can include "parenting", but in this case the distinction is between "got it somehow from autistic-leaning parents" vs got from something else.
Also, the claim that autism might be somehow learned from parents is extraordinary and not widely claimed or supported by existing evidence. It was a discredited theory of the past though, that "cold" parenting created austism.
There are some evidence that hints to genetic factors. For example, we know that boys are at much higher risk than girls, but we don't know why. Similarly, we know that older parents are more likely to have autistic children—but again, we don't know why.
See https://www.verywell.com/autism-4014759
Also the boy/girl factor could be explained by different behaviors, so different exposures.
Not saying I know anything about this, or that this is the case, just that the increased family risk and boy/girl risk doesn't mean it is genetics.
That's correct, but looking at concordance rates between monozygotic (identical) and dizygotic (fraternal) twins demonstrates that there is at least a partial genetic connection.
Identical twins share the diagnosis in 77% of cases, while fraternal twins only share the diagnosis in 31% of cases.[1] Given that identical twins share more genetic material, the conclusion is that autism has a genetic component to its incidence.
That said, most research on the subject, including the paper I'm citing, establishes that there is most likely a dual nature-nurture component. In particular, this study was conducted on twins within the same household, so the genetic component would have been augmented by shared environmental factors.
[1]: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4440679/
My son is the third or fourth generation to be likely-diagnosable, for example.
Currently-middle-aged parents without intellectual disability had almost zero chance of being diagnosed as children, because when we were kids autism was defined such that you usually had to be nonverbal or intellectually disabled to qualify.
A very commonly-reported experience is for parents to be diagnosed after their children are diagnosed.
Takeaway: it's a mix of both genetics and environment.
https://www.ted.com/talks/wendy_chung_autism_what_we_know_an...
http://www.npr.org/sections/health-shots/2015/09/02/43674237...
(Audio controls in the left margin.)
He addresses that a fair bit, mentioning that autism is one of the most heritable conditions, and talking a lot about the history of the diagnosis and how it was artificially narrow for a long time.
Personally, my bet is that we'll come to see a lot of autism diagnosis as part of a broader pattern of medicalization of deviance from the norm. And that even the forms we eventually decide are harmful have for nerds the same relationship that sickle-cell anemia does to malaria resistance: a trait that is useful in small doses but can be harmful in large ones.
If there is an actual increase, I'd bet on it being due to stronger assortative mating that has come as mate choice has less to do with geographic factors and more with education and workplace.
Well, considering the fact that "heritability" is a measure of how much of a given phenotype's expression is due to genetic variation, probably not soon. "Heritable" is not a word used to refer to environmental factors such as parental care and upbringing. In studies on heritability of specific traits, these environmental factors are used as classifications for broader observations of genetic variations (for example, in twin studies, was twin pair A raised in the same household like pair B?).
Going back to autism specifically, the Simons Foundation Autism Research Initiative identified a single genetic mutation that accounted for 25% of diagnoses in their Simplex Collection[1], while the other 75% were impacted by 200-400 different genes. This data is available online as of 2016[2], though some analyses may be paywalled.
[1]: https://sfari.org/resources/autism-cohorts/simons-simplex-co...
[2]: https://www.simonsfoundation.org/features/foundation-news/si...
https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...
That chart shows the rate of increase in autism diagnosis, which is not the same.
It's a trait (trait cluster, really), analogous to intellectual disability or giftedness, rather than analogous to a condition with a single known cause like trisomy 21. See https://intellectualizing.net/2013/12/17/book-rethinking-aut... and https://intellectualizing.net/2015/06/04/why-it-matters-whet...
Once we understand that autism isn't a single condition, a lot of the ways the public (and researchers) talk about autism turn out to be kinda nonsense.
But your point still stands, and has clear parallels in other cases, like sickle-cell anemia: one copy of the gene is helpful, so it remains in the population, but two copies is harmful, so its spread is limited.
Are they aligned with natural selection processes in the environment.
So, I've always thought of us as the next thing after homo sapiens. Jokingly call it Neosapiens from a cartoon as it was a cool name. Not likely to actually happen but a nice example of how the world might have been better. My ideal one, though, preserves the different types of people with two modifications: built-in mechanism where causing harm to others makes individual experience personal pain; built-in need to connect outside local sphere to reduce isolationism. These two would keep world more interesting than the safe, autistic one while also eliminating many problems. Just two, small changes in the brain.
This was a problem for the Autreat conference. It was made by autistics for autistics. The coordination required to create it was a big problem. I wonder if things would get better if they were the norm. I'm not sure.
Personally, I am not big on better/worse, but just different. E.g., we could look at white people as a weird mutation of true humans, one shockingly prone to skin cancer. Of course, as a white person, I'd rather see myself as an equally valid kind of human.
For a while I've been wondering what the DSM would look like if non-neurotypical people were in the majority. If we had a diganostic category for what we now call "normal" levels of sociality, selfishness, manipulation, violence, etc.
Interestingly, I think a good chunk of the diagnosis would be the autistic equivalent of what normal people call psychopaths. They'd be seen as irrational and dangerous, esp in groups.
Otherwise you end up having to debate whether people with lactose tolerance are more evolved than people without, and so on. It gets messy.
Also, the history of eugenics. Autistic people have been sterilized and institutionalized, really quite recently. So I'm allergic to talk about people being more or less evolved.
Very well could be.
So in addition to twin frequency, it would be worth analyzing twin spread: what is the variation in the behavior of twins (in the background), and is the spread in autistic/non-autistic twin pairs statistically similar, ie, are we just selecting for normal, expected variation that happens to fall close to a boundary?
(There is one mutation that causes something like autism, fragile-X)
I don't think cities are a result of social behavior, it's more the result of economic behavior. Cities are clusters of box apartments, which don't really demonstrate social behavior.