NEW YORK - The question of nature versus nurture is an important one, but also an incredibly delicate one.
How much of the disparities we see in society are fueled by a lack of good education, social influences and role models, and how much are due to natural ability? Given that people in advanced countries spend multiple decades of their life in school, this is an important question.
But it’s also a very fraught one — discussions about the issue are frequently hijacked by people pushing racist or sexist theories, and polite society’s reaction, understandably, is often to make such discussions taboo.
As a result, it’s hard to know what people really think about the nature-versus-nurture question. My impression is that most Americans subscribe to a casual, reflexive faith in the primacy of inborn ability. Several years ago, my doctoral adviser Miles Kimball and I wrote a widely read article lamenting American students’ lack of effort in mathematics. We believe that many Americans don’t try hard because they believe that all math skill is innate — a “fixed mindset,” as described by Stanford University psychologist Carol Dweck.
Some recent research appears to support the first part of our hypothesis. Bentley University economist Jeff Livingston found that paying American students cash incentives causes them to do better on the PISA, an international standardized test of math skills. But similar incentives had no effect on Chinese students, implying that Americans are slacking while Chinese students are trying hard.
So effort matters. But what about education itself? There is a common belief that life outcomes are heavily determined by IQ. And many websites will confidently tell you that “your IQ score is relatively stable, no matter what education you acquire.” But this is false. Some startling new research shows that education actually raises IQ substantially.
Psychologists Stuart Ritchie and Elliot Tucker-Drob have a new meta-analysis of papers that study the effect of education on IQ. Because smarter people can be motivated to stay in school longer, Ritchie and Tucker-Drob consider only studies that use natural experiments — things like policy changes, or arbitrary cutoffs, that determine how much classroom time people get. Altogether, the studies they survey represent 600,000 people — a huge sample. They wrote:
“We found consistent evidence for beneficial effects of education on cognitive abilities, of approximately 1 to 5 IQ points for an additional year of education. … (T)he effects persisted across the life span, and were present on all broad categories of cognitive ability studied. Education appears to be the most consistent, robust, and durable method yet to be identified for raising intelligence.”
Since the standard deviation of IQ is 15 points (most scores are between 85 and 115), a one- to five-point improvement per year of education is an absolutely enormous effect. Ritchie and Tucker-Drob’s result doesn’t mean that nature doesn’t matter at all — it clearly does — but it indicates that nurture, in the form of education, is extremely powerful.
How about the notion that smarts determine life success? That idea too has come under assault from recent research. A recent paper by economists Alex Bell, Raj Chetty, Xavier Jaravel, Neviana Petkova and John Van Reenen — a star-studded list of names — finds that at least for certain kinds of achievement, factors other than natural ability matter quite a lot.
Bell et al. study invention — specifically, how many patents someone has to their name. Invention is different from innovation and patents aren’t a good measure of how economically useful a discovery is. But patenting does measure a specific kind of intellectually demanding, rigorous and often highly compensated form of work — if you get a job doing something that involves being awarded a patent, chances are that your economic situation is pretty solid.
Since mental ability matters for invention, Bell et al. control for performance on childhood math tests. But huge gaps remain — between rich and poor, and between white men and other demographic groups. Poor people, women and minorities all produce many fewer patents than wealthy white men with equivalent math test scores.
What explains the difference? Bell et al. think that human influence matters a lot. They find that even controlling for math ability, people whose parents are inventors tend to become inventors themselves. Neighborhoods also matter; people who grow up around a lot of inventors tend to become inventors when they grow up.
Bell et al. don’t have the data to study role models — who kids see on TV or on the internet doing science and engineering. Nor can they observe the mentors that people encounter in their adult life. But the effects of parents and neighborhoods imply that role models and adult mentors might also be key reasons why women and minorities are underrepresented among the ranks of inventors.
So many different kinds of nurture matter in determining success. Effort matters. Education matters. And social environment matters. Americans discount these factors too much. The country would be a better, richer, more equal place with less emphasis on natural talent and more on humans’ potential to improve each other and themselves.
Noah Smith is a Bloomberg View columnist. He was an assistant professor of finance at Stony Brook University, and he blogs at Noahpinion.