Last time, we discussed what was known about the causes of Autism Spectrum Disorder. The evidence from twin studies showed that if you share genes with someone who has Autism, chances are really high that you will also have Autism. So the disorder has a strong genetic link. We also saw that there is not one “Autism gene” responsible for the disorder, but many genes that are associated with increased risk of Autism. In fact, it looks like there are probably hundreds of genes, each one slightly increasing the risk that you will have Autism.
Not only are there hundreds of genes that increase the risk of developing Autism, but in fact most of those genes are commonly found in our population. That means that if someone took a sample of your DNA, it is almost guaranteed that they would discover that you have dozens of these Autism genes. So if each of us has dozens of Autism genes but did not develop an Autism Spectrum Disorder when we were kids, what are those genes doing? Because Autism is such a devastating disorder, it is tempting for us to think of those genes we have as bad. But for those of us who inherited lots of Autism genes but not enough to develop the disorder, could those genes be giving us some benefits?
This is the central question of a recent study that was published by one of the World’s leading Autism scientists, Dr. Sam Wang from Princeton University. Dr. Wang and his fellow scientists asked the incoming class of Princeton freshmen what their intended major was and if they had any family members who had psychiatric illnesses such as Autism, Depression, Drug Abuse, and so on. They took the results from this survey and came up with a very simple ranking system. If you have an immediate family member who has depression, bipolar disorder, or drug abuse then add one for each disorder that is in your family. If you have an immediate family member who has Autism subtract one. So if your dad has an Autism Spectrum Disorder, you get ranked as a -1. If your dad has an Autism Spectrum Disorder and your mom has bipolar disorder, you get a 0 (-1 + 1 = 0). And so on. They then compared these results with what the students were interested in studying. Below are the results they found
Notice that people who had a family member with Autism and no other disorders in their family (score of -1) were almost exclusively interested in technical fields like science, mathematics and engineering. What does this mean? Well if someone in your family has an Autism Spectrum Disorder, that means the genes are in your family so you probably have quite a few of those genes yourself. What are the prototypical traits of Autism? Difficulties in processing social and emotional information and a tendency to be overly focused on technical details. This suggests that those Autism genes give you a predisposition to be interested in technical things and less interested in social sciences or humanities. I would love it if readers indulged my curiosity and posted in the comments how this scoring system predicts your own interests.
Inheriting these Autism genes might help your brain develop in such a way that you are likely to be especially interested and gifted in technical fields like science, engineering or mathematics. If you inherit too many of these genes, you can get pushed too far down that pathway and find yourself so interested in technical things that you lack social and emotional abilities. Think of these Autism genes in the population as a bell shaped curve.
Almost everyone in the population has some Autism genes. In these people, the genes help your brain develop with an interest in math, science and other technical things. Some people inherit more of these genes and find themselves really drawn to those fields, while others inherit less of those genes and find social and emotional fields more appealing. This variability is a good thing for our population. We need some people to be our mathematicians and scientists and engineers. We also need some people to not find that interesting and become our artists, entertainers, or other social occupations. The trouble is with any curve you have a small segment of the population that finds itself at the extreme ends, and in this case that extreme end is Autism.
From this viewpoint Autism is not a “disease” as much as an imbalance. It could be that people with Autism Spectrum Disorders just inherited so many of these genes that push their brains to be especially good at processing technical interests that they don’t develop enough processing power for social and emotional topics.
It is very tempting to read a lot into this relationship between Autism genes and interests in technical fields, but we need to exercise caution. There are other possible explanations of why this is happening. It might be that the experience of growing up with someone who has Autism presents a unique set of circumstances that tends to shape young minds away from social fields like the humanities and towards natural ones like science. Just because the two things are related, doesn’t mean you can say for sure that the autism genes are the cause and the interest in technical fields is the effect.
Still, if it’s true and these genes are causing an interest in technical fields it would go a long way to help explain why Autism genes are so commonly found in human populations. Genes that cause major deficits and diseases are rare because the people who get them have deficits and diseases. The more difficulties you have the less likely you are to successfully have lots of children and pass those genes on to the next generation. Since these Autism genes are relatively normal in the human population, it makes sense that they have some benefits associated with them; it’s just that getting too many of them pushes the scale too far and becomes problematic.