Frederick Jackson Turner had an idea that American democracy was forged on the frontier, in harsh conditions that promoted risk-taking, individualism, and a disregard for old customs and hierarchies. Some modern immigration scholars have a related theory, called “voluntary settlement hypothesis,” which posits that self-selection tends to produce groups of immigrants who are more autonomous, independent, and goal-oriented than their neighbors who stayed behind—whether they’re going to a cabin in the hills or a tenement in the city.

That would burnish Turner’s ideas about frontier culture, but it would also suggest that regions that underwent the highest rates of out-migration would be shaped by the opposite effect, having lost their most individualistic members to the lure of a better life. (Kind of like brain drain.)

Of course, measuring this phenomenon in terms of personality is difficult in a world where who gets to migrate is decided by geographic birthright, education, legal wherewithal, and money. Go back to the 19th century, and the playing field was a little more even; the United States didn’t pass its first immigration law, the notorious Chinese Exclusion Act, until 1882. European immigrants continued to arrive without restriction for several more decades. From a research perspective, the problem with looking at those people is: How can you reach back in time and get a hold of someone’s personality? How can history inform us about the kinds of people who leave or stay?

In a new working paper, the economist Anne Sofie Beck Knudsen took a clever approach: She used uncommon first names as a proxy for individualism. (Yes, there is research that backs that idea up—see her paper for more.) Then, using the extensive migration records kept by Norway, Sweden, and Denmark during the late 19th century—a database of more than 1 million first-time Scandinavian emigrants—she tried to figure out if Scandinavians heading to America were less likely to have common first names. They were.

Because migration rates from Scandinavia to the United States were so high—the three countries lost 25 percent of their populations between 1850 and 1920—Knudsen thinks this would have substantially changed the makeup of the three countries, lowering the rates of individualists by 3.7 percentage points in Denmark, 9.4 points in Sweden, and 13.6 points in Norway. Wondering why Scandinavians have such high rates of social cooperation today? Maybe it’s because they sent all their individualists to America 100 years ago.

Or, at least, people with weird names.

Working within the social geography of 19th-century Scandinavia, Knudsen thinks, this method makes more sense than it would today. The countries were pretty homogeneous. Social and physical geography were basically coterminous—the people you lived near were the people you knew—and so to pick out what counts as an “uncommon name” (and infer from it ideas about that household) Knudsen felt comfortable relying on regional naming patterns.

Still, she had to control for things. Gender: Boys have more common names. Older children, too. Family structure changes naming dynamics. Biblical names and Scandinavian names, to control for religiosity or nationalist sentiment. Even accounting for all that: Scandinavians who had been raised in “individualistic households,” as implied by their parents’ unconventional naming choices, were more likely to migrate.

As a bonus, Knudsen used U.S. census data from 1900 and 1910 to see what had become of those people once they crossed the ocean. Sure enough, migrants with uncommon names were more likely to speak English, less likely to have married a compatriot, and less likely to choose a Scandinavian name for their own children.