A long profile of economist Raj Chetty includes a section on his look at the concept of social capital:

Chetty has found that opportunity does not correlate with many traditional economic measures, such as employment or wage growth. In the search for opportunity’s cause, he is instead focusing on an idea borrowed from sociology: social capital. The term refers broadly to the set of connections that ease a person’s way through the world, providing support and inspiration and opening doors.

Economics has long played the role of sociology’s annoying older brother—conventionally accomplished and wholeheartedly confident, unaware of what he doesn’t know, while still commanding everyone’s attention. Chetty, though, is part of a younger generation of scholars who have embraced a style of quantitative social science that crosses old disciplinary lines. There are strong hints in his research that social capital and mobility are intimately connected; even a crude measure of social capital, such as the number of bowling alleys in a neighborhood, seems to track with opportunity. His data also suggest that who you know growing up can have lasting effects. A paper on patents he co-authored found that young women were more likely to become inventors if they’d moved as children to places where many female inventors lived. (The number of male inventors had little effect.) Even which fields inventors worked in was heavily influenced by what was being invented around them as children. Those who grew up in the Bay Area had some of the highest rates of patenting in computers and related fields, while those who spent their childhood in Minneapolis, home of many medical-device manufacturers, tended to invent drugs and medical devices.* Chetty is currently working with data from Facebook and other social-media platforms to quantify the links between opportunity and our social networks.Sociologists embrace many ways of understanding the world. They shadow people and move into communities, wondering what they might find out. They collect data and do quantitative analysis and read economics papers, but their work is also informed by psychology and cultural studies. “When you are released from the harsh demands of experiment, you are allowed to make new discoveries and think more freely about what is going on,” says David Grusky, a Stanford sociology professor who collaborates with Chetty. I asked Princeton’s Edin what she thought would end up being the one thing that best explains the peaks and valleys of American opportunity. She said her best guess is “some kind of social glue”—the ties that bind people, fostered by well-functioning institutions, whether they are mosques or neighborhood soccer leagues. The staff at Opportunity Insights has learned: When an economist gets lost, a sociologist can touch his elbow and say, You know, I’ve been noticing some things.