How to Seek and Not Find
This rather simplistic view of sociology, neurodevelopment and genetics has been heralded, nay, brayed to the world as "proof" that mercury causes autism. Now we are presented with another possible explanation of Mr. Olmsted's amazing findings.
In the 30 March 2006 edition of The New England Journal of Medicine (not up the "standards" of Medical Hypotheses, to be sure, but a solid journal nonetheless), a group of researchers from the Clinic for Special Children in Strasburg, Pennsylvania (which provides services to a large number of Amish and Mennonite children) report a genetic mutation which causes:
"...seizures that progress to autism and retardation" (see here for a nice review of the article)
This mutation is seen in much more often in Amish and Mennonite children, primarily because of their very small gene pool (see here and here for a review). This is not the only genetic disorder seen more frequently in these populations. And this is not to say that this is the same sort of autism generally seen in the general population (it's not).
However, it seems passing strange that Mr. Olmsted, in his extensive canvassing of the Lancaster County Amish communities, did not run across a few of these children. They are, after all, autistic, even if they weren't vaccinated.
Three possibilities leap to mind (there may be others):
[a] Mr. Olmsted didnt look all that carefully for autistic children, having already concluded that there wouldn't be any.
[b] Mr. Olmsted found these autistic children, but didn't count them - either because he (as a trained neurologist and developmental pediatrician) didn't feel that they had real autism or because it conflicted with his forgone conclusion.
[c] The Amish families - being somewhat suspicious of "outsiders" (not without good reason) - didn't confide the details of their family medical issues with Mr. Olmsted.
My money is on [a], with a bit of [c] thrown in for good measure.
One thing my thesis advisor told me early in my education:
"If you don't look for contradictory data, you won't find it. But your critics will."