Although scientists don't know what these specific areas of our DNA actually do to enable a person to complete more years of schooling, many of them are located near genes affecting fetal brain development.
What's the reason for the reduction of these genes in Iceland's population? People with this particular set of markers are waiting longer to have kids, resulting in fewer offspring.
Now before everyone goes off and cites the cult movie "Idiocracy," in which the effect of less intelligent people having more kids over multiple generations is disastrous, consider that a number of studies comparing identical and fraternal twins suggest that genetic factors only account for around 40 percent of educational attainment. The set of genetic markers that the Iceland study looks at accounts for only around one-tenth of that 40 percent.
Genetics of Educational Attainment is Complicated
There is no single gene that determines how high someone will go in terms of education. A recent study found at least 74 different areas of our DNA that affect someone’s eventual level of education. The Icelandic study bumped this number up to 120, but all together, these markers still only account for just under 4 percent of the number of genetic components that scientists have calculated affect a person's eventual number of years of schooling.
This should not be surprising. Something as complicated as educational attainment is going to involve lots of different attributes, such as drive, persistence and raw intelligence, each of which can be broken down further. Many genes work together to impact the biological parts of these traits.
And of course, as is true for most any trait this complex, multiple factors play a role: our environment in the womb, where we grow up, how our parents treated us, etc. all contribute in some way to how much education we will go on to receive. In fact, the environment of modern society has led to an increase in the number of college degrees rather than the decrease predicted by this genetic study.
So while the Icelandic researchers definitely observed a decline in a certain set of DNA markers over the last century, it is unclear what effects, if any, will result. It may be that in the long run, environment will trump genetics, resulting in more Ph.D.s than we'll know what to do with.
At first it might seem odd to do a study like this on a small, relatively isolated population like that of Iceland. But it isn’t.
Icelanders have extensive genealogical records going back centuries, and most Icelandic people have had their DNA mapped. This allowed the researchers to compare generations and track the decline in these markers.
The researchers also had access to extensive records on people going back hundreds of years, including birth dates, number of offspring and educational level. This depth of information is a veritable treasure trove for genetic researchers.
Of course studying such an isolated group does have one big disadvantage—it is unclear whether these trends are specific to Iceland or if they are more universal. So additional work will need to be done with a more diverse population to see if the results hold up.
The Debate Around Researching the Genetics of Intelligence
One but by no means the only component of getting an advanced degree is raw intelligence. Researching the genetics of that trait has been somewhat controversial. A December 2015 National Geographic article reported on a meeting to discuss the issue at the Hastings Center, a bioethics think tank. At the meeting, Dorothy Roberts, a professor of law and sociology, "disagreed with some behavioral geneticists' claims that their work would help intellectually disadvantaged children... ," reported National Geographic. Instead, Roberts said, the research would be used to support “racist, classist, gendered notions of intelligence."
But intelligence itself is so complex, the genetics of it may eventually prove to be no match for environmental factors. As this National Library of Medicine primer on the subject says, "A person’s environment and genes influence each other, and it can be challenging to tease apart the effects of the environment from those of genetics."
We are, after all, much more than our genes.
Jon Brooks contributed to this post.