Snakes On A Plane

This post isn't about the movie, "Snakes On A Plane" mostly because I haven't seen the movie yet as much as I'd like to. It won't be released until August.

This post is about convergence, or convergent evolution. A good example of convergent evolution is the way two different species of fish, at separate ends of the globe, both developed natural anti-freeze chemicals so they can live in frigid waters or be frozen alive.

Another example is the similarities between the Emerald tree boa of South America and the Green Tree Python from Australia.

To the untrained eye both look nearly identical.

They even coil themselves on a branch the same way but, other than the fact that they are both snakes, they are separated by continents, oceans and millions of years of evolution. Boas and Pythons are only distantly related and probably share an ancient ancestor but these two species evolved to take advantage of similar niches in the environment which caused or allowed them to develop similar traits even though they are very different animals.

Before the advent of modern transportation it would have been rare to find a Python in the Americas or to find a Boa outside of the Americas. Now former pet pythons can be found living in the wild in places like the Everglades. They have no trouble surviving since the environment is similar to their natural environment and there is plenty of prey. The only thing keeping non-native species from invading Florida all of these years was lack of transportation.

Another example of convergent evolution springs to mind. The vaccine/autism causation hypothesis. A few parents observed an apparent regression into autism around the time their children received routine childhood vaccines. In the UK, the theory that persistent measles infection in the GI tract was causing symptoms of autism began to evolve. In the US a group of parents were busy looking over the list of ingredients in several vaccines when they saw something called thimerosal on the list. An internet search revealed thimerosal as a chemical compound of mercury. The idea of autism as a novel form of mercury began to evolve.

Many years later both hypotheses have taken on a life of their own and evolved to incorporate new findings from mainstream autism research. Both are still short on scientific evidence but continue to exploit a niche where the vaccine autism connection enjoys popular support. Strangely the two groups have commingled and exchanged ideas and they are showing signs of converging in to a single entity.

We see chelation experts boarding airplanes to promote their snake oil and ideas about autism and mercury overseas. We have parents of autistic children getting on airplanes to seek treatment in the US. When Andrew Wakefield found himself unfairly prosecuted and unemployed he got on a plane and flew to Florida to work with Jeff Bradstreet at the International Child Development Resource Center (ICDRC).

Wakefield is now the Executive Director of Thoughtful House still plugging away at the measles and MMR hypothesis. On the Thoughtful House list of advisors we find Mark Blaxill, vice president of mercury interest group Safe Minds, and Steve Walker who will be boarding a plane bound for Montreal next week to present a poster at the IMFAR conference. Walker claims he has replicated Wakefield's earlier work and detected vaccine strain measles in tissue from guts of autistic children collected by Arthur Krigsman, also involved with Thoughtful House. Odd that Wakefield isn't listed as an author but I guess this is meant to be independent confirmation of measles virus. Of course there is this one caveat:

The research, which is being presented at the International Meeting for Autism Research in Montreal this week, has yet to be published in a scientific journal and subjected to peer review.

So the poster hasn't been presented, the study hasn't been published or peer reviewed, the presence of vaccine strain measles has not been independently confirmed, and the media is already predicting a drop in MMR uptake rates?

No surprise that the MMR and mercury hypotheses are coming together. To have an 'autism epidemic' on one side of the Atlantic where the majority of autism is caused by measles, and similar rates in the US where thimerosal is the major cause, the two will have to share resources, adapt and coexist if both are expected to survive in the same niche.

In the Mini-review, Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism
C. BADCOCK & B. CRESPI, we find the following paragraph:

Finally, autism is a highly convergent disorder, in that a fundamentally similar phenotype can result from a multiplicity of disparate genetic and environmental effects (Gillberg, 1992; Herbert, 2005). Thus, autism is common in single-locus genetic disorders such as Rett syndrome, fragile X syndrome, tuberous sclerosis and Angelman syndrome, and it can be environmentally induced by prenatal valproic acid, thalidomide or viral infection (Cohen et al., 2005; Libbey et al., 2005; Miyazaki et al., 2005).

This is important for several reasons. We are able to recognize and accept that the symptoms of autism, the set of behaviors we call autism, can arise as a result of several very different effects including purely genetic, infectious, and exposure to certain substances including pharmaceutical products.

The argument put forward by those who believe vaccines cause autism is this: "Then why can't thimerosal and measles be added to the list of causes?"

There is no reason why they can't be added to the list but there are many reasons why they haven't been added thus far. For one, the known environmental causes of autism (viral and pharmaceutical) don't cause autism in every case of exposure but every case can be traced to prenatal exposure and a fairly narrow window of opportunity at that.

We know maternal Rubella infection can cause autism in some cases but there are no records of postnatal Rubella exposure leading to autism. As far as I know, there are no records of measles exposure at any age causing autism. I'm not saying it couldn't happen but the lack of precedence would make it all the more extraordinary and we know what they say about extraordinary claims. If wild strain measles isn't known to trigger autism, and several other viruses are, what is it about the attenuated strain in the MMR that makes it so unique and extraordinary?

What about drugs like Thalidomide and Valproic acid? Very few people deny they can contribute to or even cause autism through prenatal exposure. If we are to believe that there is a vast international government and pharmaceutical conspiracy and cover-up to deny the role of thimerosal, why aren't the manufacturers of these drugs able to keep a lid on their problems? After all they have fewer employees, there is no mandatory uptake, and fewer children are effected.

The manufacturer of one drug doesn't bother to deny that their product may have caused autism in some cases.
Families challenge epilepsy drug firm

“At all relevant times, the product information supplied to doctors by Sanofi-Synthelabo in relation to sodium valproate provided warnings in respect of possible effects in children born to mothers who take the product during pregnancy.”

Why? Probably because there is adequate evidence of cause and effect which hasn't been demonstrated for thimerosal or MMR no matter what we may hear. Sure there are a lot of theoretical mechanisms that are said to do this and that but like every other evolutionary process, the theories that don't hold up to prevailing conditions will be discarded in favor of newer and more exotic ideas. Just look at some of the ideas and treatments promoted by DAN! and company only a few years ago.