A hypothesis must be testable to qualify as a hypothesis. Then it must be tested, failing falsification many times in many different ways, before being accepted as a 'Theory'.
This is why your theory about vaccines gets laughed at, while your hypothesis about vaccines gets you hummed at.
The most common version of the Hypertrophy Hypothesis of Autism states that the epigenetic changes that are required to produce an autistic individual are acquired over one or more generations where the following conditions are satisfied:
1) The mother's food was very regular.
2) The mother's food was fully nutritious.
3) The mother never genuinely believed that starvation was an option for her family.
In order to test this part of the hypothesis, we would need to find two populations, as similar in ancestry as possible, where one population had suffered considerable periods of widespread starvation but the other had not.
Planet earth, with all it's separate nation states and laws, provides a huge laboratory rich with data. If only we can work out how to mine it...
Last year, a South Korean study found an estimate for the autism rate within their country by screening large numbers of children. The criteria for 'autism' were very loose so the research gave us a figure of approximately 2.5% of South Korean children having some form of autism.
If we sent the same team to North Korea, to perform the same testing on North Korean children, the Hypertrophy Hypothesis makes the following prediction:
Autism rates in the North will be significantly lower than autism rates in the South, even after adjusting for all other known risk factors.
Getting permission to do the research may be a bit of a problem. However, if the autism rate is likely to be lower than the South's, then the North might be just interested...
PS. Still hung up on the 'Neanderthal Hypothesis of Autism'? There's a test for that too. In the meantime, find me 100 full-blood ethnic south Africans with Autism and we can say *goodnight darling* to the Neanderthal story.
We won't be silenced by those who won't be silenced. Quis custurd pudding et π.
DISCOVER Magazine Blogs - Gene Expression:
ReplyDelete"Africans aren’t pure humans either" (Sept 5, 2011)
Last year when discussing the possible admixture of Neandertals with the ancestors of modern non-Africans I joked that Sub-Saharan Africans were “pure humans.” This was tongue-in-cheek in part because the results from the Neandertal genome shifted my assessment of the probability of archaic admixture within Africa as well. In other words, there may never have been a pure “human” type which expanded and assimilated archaic ancestry on the margins of its range. Species Platonism may be very misleading for our particular lineage. Rather, what it means to be human has always been in flux, a compromise between extremely different ancestral components.
http://blogs.discovermagazine.com/gnxp/2011/09/africans-arent-pure-humans-either/
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"Autism, Intellectual Disabilities Related to Parental Age, Education and Ethnicity, Not Income, Utah Study Finds"
They evaluated a variety of demographic factors and found that children with ASD but not ID were significantly more likely to be male and to have mothers of white, non-Hispanic ethnicity. Children with both ASD and ID were also more likely to be male, but were more likely to have mothers older than 34 years of age. Children who had ID but not ASD were significantly more likely to have fathers older than 34 years of age and significantly less likely to have mothers with more than 13 years of education.
http://www.sciencedaily.com/releases/2011/09/110919093856.htm
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"Racial Disparities in Community Identification of Autism Spectrum Disorders Over Time; Metropolitan Atlanta, Georgia, 2000–2006"
Total ASD prevalence was higher for NHW (Non-Hispanic White) than NHB (Non-Hispanic Black) children, but NHB children were more likely than NHW children to have autistic disorder and autism eligibility at a public school documented in records. NHB children were less likely than NHW children to have pervasive developmental disorder-not otherwise specified and Asperger's disorder documented in records, even after controlling for socioeconomic status. NHB children were more likely than NHW children to have co-occurring intellectual disability.
http://journals.lww.com/jrnldbp/Abstract/2011/04000/Racial_Disparities_in_Community_Identification_of.1.aspx
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"Childhood Autism in Africa" (1978)
This was not a study of prevalence. Yet from indirect evidence the numbers of autistic children found was much smaller than expected. [...] If the incidence of childhood autism is assumed to be similar in Africa and Britain, there is no obvious reason why relatively fewer such children should be found amongst the known severely subnormal population in African countries. A possibility therefore is that autistic symptoms generally are less common in the African countries we visited, than in Britain.
A further possibility is that certain specific aspects of the syndrome occur less frequently in the African populations.[...] Our general impression, confirmed informally by psychiatrists and other institution personnel in every country we visited, was markedly different from that described by Kauffman and Levitt who state, "a visitor to an institution for mental defectives is quickly impressed with the large number of patients engaged in various forms of stereotyped behaviours" (1965a, p. 467)...
The relationship between the occurrence of childhood autism and social class, first described by Kanner (1943) cannot readily be accounted for by selective referral (Lotter, 1967).
http://www.scribd.com/doc/63020653/
Also, the question at 51:46 in this video is relevant: http://www.youtube.com/watch?v=Z6ZfrXHgiVY
Yes I guess we should address the Neanderthal hypothesis properly. To the average person, it looks pretty plausible and the average paleogeneticist wouldn't even begin to know how to explain to the average person that it's simply not plausible from a technical perspective.
DeleteI think that when one is comfortable with the 'cannibal' hypothesis of autism, then it's clear to see why so many autistic features would seem to tend towards the neandertal end of homo-averageness, as it were.
Are you familiar with the silver fox breeding experiment? You can't make a dog-like fox without it starting to look dog-like, and you can't evolve into a human-eating human without starting to look like the old human-eating humans did.
I forgot to ask, were you already familiar with the cannibal hypothesis?
"the average paleogeneticist wouldn't even begin to know how to explain to the average person that it's simply not plausible from a technical perspective."
DeleteNo. It's quite plausible:
Autism: The Eusocial Hominid Hypothesis
Abstract:
ASDs (autism spectrum disorders) are hypothesized as one of many adaptive human cognitive variations that have been maintained in modern populations via multiple genetic and epigenetic mechanisms. Introgression from "archaic" hominids (adapted for less demanding social environments) is conjectured as the source of initial intraspecific heterogeneity because strict inclusive fitness does not adequately model the evolution of distinct, copy-number sensitive phenotypes within a freely reproducing population.
Evidence is given of divergent encephalization and brain organization in the Neanderthal (including a ~1520 cc cranial capacity, larger than that of modern humans) to explain the origin of the autism subgroup characterized by abnormal brain growth.
Autism and immune dysfunction are frequently comorbid. This supports an admixture model in light of the recent discovery that MHC alleles (genes linked to immune function, mate selection, neuronal "pruning," etc.) found in most modern human populations come from "archaic" hominids.
Mitochondrial dysfunction, differential fetal androgen exposure, lung abnormalities, and hypomethylation/CNV due to hybridization are also presented as evidence.
http://www.scribd.com/doc/74944514/
If we are hypothesising that autism is an expression of neandertal traits which will be betrayed by genetic studies, then where is the boundary? How does one get a pass/fail as a neandertal/autist?
Delete1% to 4% 'neanderthal DNA' in the average 'modern human' (excluding the above mentioned Africans). Does this mean that 4% is the maximum possible? And how much neanderthal to modern human ratio does that express? Is it 4% or more? Are we talking about a probability distribution? With 7 billion on the planet, if 1 to 4 is the 99 percentile on the bell curve, we've still got a good chance of a few 51%-ers, but not 70 million of us!
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Go back to the silver fox breeding experiment. When foxes were artificially selected for short fight distance, they began to show dog-like morphology. The gene which makes a fox and a wolf's tail stay down is the same gene which makes the dog's tail stay up. When the silver foxes were selected for short flight distance (i.e. domestication) then the gene for the tail up is activated.
Are we to conclude that these silver foxes inherited their vertical brushes from dogs?
No. So the morphological similarities and the genetic similarities between neandertal and modern autist are absolutely no proof whatsoever that autism is somehow arising as a consequence of DNA from neandertals.
Even if it's true, then one could claim that autism was caused be the weather, which was the reason for the common ancestors of modern humans and neandertals speciating in the first instance.
What neandertals and autists do have in common is traits, both genetic and morphological, that favour the shift from omnivorousness to hyper- carnivorousness but in neandertals it was activated by cold and the need to eat bears. In autists it is activated by the 'dna memory' (you know teem theory?) of having a rich, high-fat, high-meat diet for several generations.
The diet which prevents schizophrenia is probably the diet which promotes autism.
The real issue is not whether or not autism is caused by 'relative superior nutrition' (you can't really call someone a 'cannibal' until they try to eat conspecifics of course!) but rather how will the world react?
Um... is this real life?
ReplyDeleteYes Robert, this is for real. Sure, autism is taboo, cannabis is taboo, cannibalism is taboo. Autism is such awfully bad luck I'd be surprised if we didn't turn out to be humbly naturally arising 'cannibals' too.
ReplyDeleteAs for the experiment, who knows? It's not impossible.
If it's not the case, then where are all the newly evolving cannibals within the human race? 7 Billion easy to catch, easy digestible people, able to reproduce fast enough to support a cannibal population of between 0.1 and 1% of the human population.
Where are the cannibals? Surely mother nature wouldn't miss out on this particular niche?