The fundamental problem with Evolutionary Psychology, like socio-biology and neuro-psychology, is that the results are precisely known, while the posited causes arise from something that is at best known only vaguely and with very amorphous defining features. This combination is the perfect combination for convincing people of something by writing some sort of reasonably argued just-so story.
A good example is the hypotheses of EP regarding autistic spectrum disorders. The result in terms of observation of rates of ASD in various places and cultures displays the following oddities:
1. Certain cultures show a markedly higher rate of autism than others, even those living in the same locale.
2. This markedly higher rate has not been a historical fact, but is a new situation: i.e. rates of ASD have increased markedly in some populations in some areas at a very rapid rate, while other populations in the area have been almost completely unaffected.
The basic story spun by Evolutionary Psychologists runs along these lines:
The dramatic increase in ASD rates in places like South Korea and China is an evolutionary trend based on their culture. The lack of empathy which is a common trait of ASD persons doesn’t impact their ability to mate and thereby reproduce the genes posited as causing the disorder. By contrast, the culture of hispanic peoples, who are gregarious culturally in a way the Chinese and Koreans are not, would make mating a difficult task for an autistic hispanic person, and as a result the required genetics, whatever those may be, do not get passed along from generation to generation, and so the incidence of autism remains low.
The problem with this particular just-so story is that it doesn’t fit the evidence conveniently left out of the EP account:
1. ASD rates are not consistent throughout China and Korea, but differ widely from geographical area to geographical area.
2. The rapid increase in rates has taken place over at most 2-3 generations, which seems unlikely to have spread a rare set of genes throughout a given population.
3. Other nations with similar cultures, such as Cambodia, have virtually no incidence of ASD.
Whether or not there is a genetic component to ASD, as seems likely from the increased likelihood of having it if it is in the family, the notion that a given result must have one origin is nothing more than metaphysical, scientific prejudice. Given the results of the human genome project, we have ample evidence that the same genes express differently given a different environmental context. In terms of something that has multiple causes, a dramatic increase in incidence points to a sudden change in one or more of these causes, but sudden changes are not the genome’s forte.
That, intuitively, points to something in the environment in which the genome expresses itself as having undergone some kind of change where the incidence has increased rapidly, and a corresponding lack of change where it hasn’t. It also points to whatever has changed affecting specific cultures and not others in the same locale, which points intuitively to something that one culture is much more exposed to than the other.
To go back to the first case, Cambodia is the example that damages the EP hypothesis most fundamentally. Since Cambodians are not culturally radically different than Koreans or Chinese (or at least not more so than Koreans and Chinese from one another) a cultural-genetic evolutionary theory runs into a problem explaining the radical difference. In terms of the second case, for the genes to be widely enough distributed to cause a radical increase in Chinese and Korean populations in the United States, but not in Hispanic peoples in the same country, would require a larger fundamental difference in the average genome between ethnicities than is observationally the case.
Since we are looking at an environmental commonality found in such diverse areas as South Korea and the United States, yet not found in a neighbouring area such as Cambodia, and not found consistently across the vast country of China, we are looking for something at once common, yet not ubiquitous. We are also looking for something that, even where common, for some reason affects certain cultures more than others. The most obvious of differences between cultures, in fact the first difference most people think of, has nothing to do with something as arcane as mating rituals, but something much more everyday – the way that food is prepared.
Looking for commonalities between all the various types of Chinese and Korean food might seem a daunting task, until you realize you simultaneously have to find a commonality not shared with either people living in Cambodia or Hispanics in the United States. One of the most obvious differences with the latter is that boiling is not the primary method of food preparation for Hispanics – even with commonly boiled foods such as rice, Hispanic peoples commonly fry the food after boiling. Drinking water directly is also not a large part of Hispanic culture, where fruit juices and alcoholic beverages are more common. Since the water in those beverages has a different origin than the water used commonly for drinking and cooking, water is the obvious place to begin a process of elimination. But what of Cambodia? The extreme poverty in Cambodia even today means that most Cambodians do not get their water, as most in China, South Korea and the United States do, from a tap. Much of the drinking water in Cambodia is captured rainwater or semi-filtered river water. Since that water is almost by definition dirtier on average than the water in China or Korea, if the culprit is naturally occurring it has to be rare in Cambodia, common in Korea, common in the areas of China with a large increase in ASD rates, and common in the United States. As well, it has to be a new toxin in most of those areas.
From the limited research i’ve been able to find time for so far, only one toxin in water meets those requirements. It is found in all tap water in the U.S. and Korea, and is naturally present in precisely the areas of China that show high ASD rates. It is rare, however, in the water found in the fruit juices and alcoholic beverages favoured by Hispanic peoples. It is also a known neurotoxin, a substance that travels directly through the blood-brain barrier, which makes it significantly more suspect when dealing with a neurological illness like ASD.
That toxin is fluoride. It has not only been implicated with powerful statistical correlations in ASD, but also in ADHD, depression chronic fatigue syndrome and even IBS. The U.K. government is about to cave to the extensive monetary power of the fluoride industry by increasing the amounts added, although adding fluoride to water, ironically, is even detrimental to teeth and bones due to its acidity, which when not countered by the generally alkaline formulas of tooth paste, causes teeth to rot and bones to lose density.