We've seen increasingly bizarre claims from social psychologists and advocates with confirmation bias: American liberals are evolving into a different species, they have prettier children, conservatives are motivated by fear, and more.
One thing is truth, people are more likely to mate by education level now, there are very few scenarios where smart people simply don't go to college in a culture where government spends money convincing young people they need a college degree. That would have to change the genetic makeup of subsequent generations, right?
Not really. In the Proceedings of the National Academy of Sciences, a popular journal for sociology, scholars used the U.S. Health and Retirement Survey to examine variation in educational attainment, height, body mass index, and depression--along with variation in genes associated with these traits--across birth cohorts (1920 to 1955) in more than 2,000 white, non-Hispanic spousal pairs. While they found an acceleration in similar levels of educational attainment between spouses over time, this trend was not reflected in genes long known to be linked with educational attainment--in other words, the similarity between spouses with respect to education-associated genes did not vary significantly across cohorts.
Moreover, no notable trends in spousal similarity or fertility were observed with respect to the other traits studied (height, body mass index, and depression) or the corresponding genotypes.
"Undoubtedly, spouses are increasingly sorting themselves with an eye toward the education they've received--among other traits," observes NYU sociologist Dalton Conley. "But while the existence of education-association genes has been well-documented, choosing partners with education levels similar to our own has not resulted in children who have meaningfully altered the genetic makeup of the U.S. population."
"Our findings underscore the fact that, while genetics are inter-related in complex manners to human social structures, it is not always the case that genetics mirror changes in human society, at least in the short term," adds co-author Ben Domingue, an assistant professor at Stanford's Graduate School of Education.