One theory I have dabbled with about rising inequality in the United States is related to the concept of natural selection. Smart people marry other smart people and have smart children.
One might argue that this pattern has been constant throughout history, and therefore there is no reason to expect it to be any different today.
However, I disagree.
There are four demographic trends that seem to have accelerated this pattern. First, over the past forty years, admission to top universities has become much more meritocratic. In the past, admission to top universities likely depended more on one’s social class than on one’s innate intelligence. Of course, there were certainly exceptions, but I think it is fair to argue that college admissions are far more meritocratic now than they were forty years ago.
Second, the internet boom in the late 1990s drew thousands of high-IQ employees from around the country to places like Silicon Valley, where they established their careers, and married other high-IQ partners. Furthermore, those with more “male-like” brains — that is, brains hard-wired to understand systems rather than empathizing with people — achieved higher status and income than their more-gregarious peers. These so-called “systemizers” include people like Bill Gates and Mark Zuckerberg.
Third, augmenting this technology boom was the influx of highly intelligent immigrants from around the world (which ended after limitations were imposed on immigration policy after 9/11). These people were literally some of the smartest people in their countries and the world, and they came to the United States.
Fourth, the number of women earning math and science degrees accelerated in the 1970s and 80s. These women entered traditionally male professions in unprecedented numbers, where they met their future spouses.
Fast forward to the present day, and many of these people have had offspring. Furthermore, recent decades saw a dramatic increase in autism rates. For instance, according to a recent article in Time, researchers believed that autism was prevalent amongst 1 out of 2,500 children in the 1980s. Today, researchers believe 1 in 110 are on the autism spectrum. Part of this increase is likely due to better screening, and another part is likely because of unknown environmental factors. However, some researchers like Simon Baron-Cohen believe another factor is at play called “associative mating.” In other words, “birds of a feather” tend to “flock together.”
For instance, Baron-Cohen discovered that two to four times as many children in Eindhoven in the Netherlands, home of the Dutch equivalent of Silicon Valley, had autism compared to children in the Dutch cities of Haarlem and Utrecht.
Of course, this theory is still relatively unproven, but it seems compelling. As these parents have children who also tend to be highly intelligent, “systemizers”, a society that favors technological innovation and quantitative skills selects for these children with higher paying jobs and opportunities at a higher rate than it does their peers. Coupled with the tendency for systemizers to be less empathetic than the average person, it is no surprise that many of today’s “wealthy” are not stirred by emotional appeals to help the poor.
Reflections of a Rational Republican 
Of course, there were certainly exceptions, but I think it is fair to argue that college admissions are far more meritocratic now than they were forty years ago.
I think, not sure if it’s post graduate programs or prestigious schools, but the exception is for minorities.
I think you can also throw legacies into that bucket, though it is not as prevalent as it used to be.
Then the autism rate in Silicon Valley would be……?
I have not been able to find precise figures, but this paragraph from a 2004 Wired Magazine article should provide some context:
“California is not alone. Rates of both classic autism and Asperger’s syndrome are going up all over the world, which is certainly cause for alarm and for the urgent mobilization of research. Autism was once considered a very rare disorder, occurring in one out of every 10,000 births. Now it’s understood to be much more common – perhaps 20 times more. But according to local authorities, the picture in California is particularly bleak in Santa Clara County. Here in Silicon Valley, family support services provided by the DDS are brokered by the San Andreas Regional Center, one of 21 such centers in the state. SARC dispenses desperately needed resources (such as in-home behavioral training, educational aides, and respite care) to families in four counties. While the autistic caseload is rising in all four, the percentage of cases of classic autism among the total client population in Santa Clara County is higher enough to be worrisome, says SARC’s director, Santi Rogers.”
Thanks Sean.
Pehaps this fits the discussion. I read a newspaper article about a year ago that linked older parents to elevated incidence of asd. Maybe the incidence is higher, not because of “systemizers” inbreeding, but because they focus on their careers and push childbearing back a few years. A look at asd in relation to birth order might give evidence of age being a factor, or way or the other.
James,
That is probably a contributor as well. It will be interesting to see if someone does a more rigorous empirical analysis of the causes of autism.
The associative mating theory is interesting, but there are simpler explanations.
The simplest, of course, is that autism diagnosis is on the rise because the disorder itself is being redefined and the category broadened. It’s not just autism now, after all, it’s the autism spectrum.
Asperger’s and other high-functioning autism disorders were frequently not diagnosed at all in the past. So-called “atypical autism” diagnoses are so vague, and so broad, that just about any form of social difficulty can be lumped into the spectrum.
To be brutally honest, I expect that thirty or more years ago, most of these kids were simply disciplined by their parents, or ridiculed by their classmates, until they learned to fake the necessary behaviors to fit in.
Chris,
Broader diagnoses are definitely part of it. That said, Baron-Cohen is arguing that associative mating is occurring in addition to this and other unknown environmental effects. Only time will tell if he is right.
I have wondered about the effects of associative breeding as well. I wonder if White people will start suffering from Tay-Sachs disease or other similar disorders.
The difference, however, is that people are selecting their partners based on attributes not necessarily related to race.
There has been a massive increase in chemicals in our environment and food, especially since the 80s. Tests done to check toxicity levels in the body here in Maine showed that people 30 and under were often at much higher levels than their parents, having been exposed to a variety of new additives and chemicals. Most of these are not really well tested in terms of their long term impact. I think that’s a better bet for explaining things like higher autism rates (which also are evident here in rural Maine). Check out the book “What’s Gotten Into Us” by McKay Jenkins.
Scott,
I think it is a mix of all four (higher reporting of autism, more environmental contamination, associative mating, and older people having children)
The Autism rate is also really high in the Seattle area.
I’m not surprised. There are plenty of Microsoft and Amazon employees there.