Wednesday, March 29, 2006

Is a Genetic Mini-Epidemic Possible?

In prior posts I argued that the California data is totally consistent with the absence of any noticeable autism epidemic between 1992 and the present time. This, however, does not preclude the possibility that the frequency of certain key alleles has changed slowly over decades or centuries.

This hypothesis is of course very speculative, and it would be impossible to test it in the short term. At best, it might be possible to carry out genetic studies of certain populations that have been isolated for a long time, such as the Amish.

What I want to do in this post is explore a number of genetic mini-epidemic theories. Note that these theories had been proposed to try to explain the explosion of autism diagnoses that started in the early 1990s. At this point we know the most likely explanation for the 'autism epidemic' is that of 'broadening criteria/awareness' – based on the changing characteristics of the autistic population and regional peculiarities. Nevertheless, these genetic theories do propose mechanisms by which the frequency of alleles might change in human populations over long periods of time, which could have intriguing implications on human evolutionary theory.

The Geek Syndrome Theory

This theory is often attributed to an article from Wired Magazine titled The Geek Syndrome (2001).

What the Geek Syndrome Theory proposes is that the success of the computer industry has helped geek types get better employment, marry and procreate in higher proportion than would have been possible in the past.

In another age, these men would have been monks, developing new ink for printing presses. Suddenly, they're reproducing at a much higher rate.

The article claims that autism "is surging among the children of Silicon Valley." It further notes that "the picture in California is particularly bleak in Santa Clara County." This specifically refers to the caseload of the San Andreas Regional Center. The statement is rather inaccurate (plus you might guess what I think about the "bleak" wording). The ratio to epilepsy in that Regional Center was 0.53 in December 2002. The same ratio in the Westside Regional Center was 1.19. As we know, the bulk of the 'epidemic' occurred in the Los Angeles area. Unfortunately, it is difficult to determine if San Andreas was slightly different to other parts of California, because of inequivalence.

There is some plausibility for this theory despite lack of supporting data. This is because a relatively high proportion of engineers and scientists can be found in the families of autistics [ref][ref]. Also, have you seen the video of Bill Gates rocking autistically?

The Assortative Mating Theory

I'm intrigued by the assortative mating theory because my father-in-law appears to be quite the Aspie, although undiagnosed. In a different time perhaps my wife and I would not have met. Today people are very mobile and are able to meet a variety of different potential partners.

This theory is proposed by Simon Baron-Cohen [ref], and it connects with his extreme male brain theory which proposes that males are good at systemizing. Baron-Cohen suggests that two parents who are systemizers might have a greater probability of having an autistic child. He further proposes that it has become easier for geeky types to meet each other because of better job opportunities, and more women working in technical fields.

Again, this theory is plausible but it counts with no supporting prevalence data.

The Genetic Drift Theory

This theory is not formally proposed anywhere that I could find but it is straight forward. In evolution theory the best known mechanism of change is natural selection. But there is another mechanism, called genetic drift. Basically what this means is that the frequency of alleles is not reproduced exactly from one generation to the next, even absent any selection pressures. In particular, if a liability suddenly becomes less of a liability, it has a greater chance of being passed down. A good example of this phenomenon is the evolution of blindness and albinism in cave-dwelling fish [ref].

In the past, autistics with immune system dysfunctions might have had reduced odds of survival. Similarly, a future where most human interaction will be carried out online might not require advanced speech or social skills.

There is some evidence that the human brain is still evolving and becoming bigger as time goes by [ref]. This could also be an effect of genetic drift. Note that a bigger brain is not necessarily free of liabilities. It implies that humans will require longer to develop. Neanderthals, who had 13% bigger brain capacity, did not have speech as advanced as that of Homo Sapiens.

Other Factors

None of these theories have any predictive relevance if pre-natal testing for autism becomes available in the near future as part of eugenics program aimed at eliminating the autism phenotype. If this comes to pass, it will likely not be without a fight. I also believe that such an event will not only be genocidal, but at the same time suicidal for the human race to carry out.

Further Reading

- Would You Have Allowed Bill Gates to be Born?

- Apology From an Autism Researcher.

- The Assortative Mating Theory: A Talk With Simon Baron-Cohen.

- The Autistic Genocide Clock.

- The Disability Rights Critique of Prenatal Genetic Testing.

- Genetic Studies of Autism: From the 1970s into the Millennium.

- Increase in Autism Caused by Modern Breeding Habits?

- The Neanderthal Theory of Autism.

- Scientific Brain Linked to Autism.

- Heritability of Autism.

- The Geek Syndrome.

- Autism Prenatal Testing


  1. Joseph,
    You might also be interested in the idea of heterosis. Here's an interesting article on this subject.

  2. That's interesting. I've wondered whether the Flynn Effect is real or not. I think the Flynn Effect has been inferred based on Weschler tests. It would probably be much better to use Raven tests.

  3. When you use Baron-Cohen to support your position, you weaken it.

  4. Check out the latest issue of the New England J. of Medicine. There is a study of a recessive gene in some Amish populations that leads to seizures and AUTISM. So much for Amish-don't-vaccinate-so-they don't-get-autism garbage.

    Strauss KA et al. "Recessive Symptomatic Focal Epilepsy and Mutant Contactin-Associated Protein-like 2" N Engl J Med 2006;354:1370-7.

  5. Joe, the extreme systemiser

  6. Joseph,
    Sorry this has taken so long to get back to you. Yes, I also wonder about the Flynn effect. I also wonder about ABA's effect on IQ - in terms of "teaching to the test". Since ABA programs are usually run by psychologists, who are familiar with the IQ test, I can't help but believe that they do emphasize skills that appear on the IQ test they are using to evaluate the children.

  7. Right, this is called the "practice effect" or something like that. I assume they use Weschler tests as well. I'm willing to bet there is probably no difference when using Raven tests (many autistics are already gifted in this test). One problem, as noted by Dawson et all, is that autistics should not be tested too early. So a follow-up study would seem to be in order.

  8. I posted on Hating Autism that assortive mating is a more likely cause of the arising number of autistics than mercury poisoning. Surprise! Foresam called me BigTime Nitwit (he's called me that a million times already!!) and told me that all it does is create more nerds that diagnose themselves with AS as adults. What an ignorant POS!!

    The invention of the internet, which people have started to use in the '90's, allowed more and more autistic like people to get together and have children. In the olden days, Aspies didn't have this opportunity. Only the lucky ones got married. Therefore, their numbers remained low due to natural selection. But technology has changed their lives, and made it much easier for them to find the right one. So indirectly, the internet is the reason there are more autistics today thatn ever before. Also don't foreget, better diagnosis adds to the explanation of the epidemic.

  9. I said...
    If autism really was mercury poisoning, then the ratio of autistics would decline. But clearly it hasn't. It has increased from 1:166 in 2004 to 1:150 in 2007. Ever since mass media about "mercury causing autism" was sent, many people have taken consideration to avoid vaccinating their children, or choosing non-mercury vaccines. But some children still developed autism. it was because at least one of the parents had some of the genes. It wasn't dental fillings, eating lots of fish, or having mercury shots during pregnancy. I know this because I research autism like no-ones business, often finding counterexamples of your statements. I think assortive mating and better diagnosis are the most likely explanations of the rise of autistics born each year.

    Fore Sam said...
    Bigtime nitwit, There are no counter examples of my statements. I don't care what you read. The fact is that over 90% of autistic kids improve with methyl B-12. If mercury was not interfering with their methylation, additional MB-12 would not make any difference.
    Your assortive mating theory only works with nitwits who diagnose themselves with Asperger's as adults because they don't like being called nerds. These people could certainly produce more nerds. Even you can understand that train wrecks who can't talk or learn to use a toilet could never get dates and reproduce.
    The flu shot with mercury, prior to the development of a blood brain barrier in fetuses is probably more effective in intentionally causing autism than the HepB at birth was since the fetuses are smaller. This has the added benefit of having the baby born brain damaged so the parents never see it act normal and they believe that crap that you try to sell. Next time you come here, try to think your argument through thoroughly.?

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