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Social Studies: Stops by Democratic and Republican cops; the power of not marrying a cousin; the mindset of water scarcity

Surprising findings from the social sciences.

A parched paddy field in India in 2009. A new study finds that people who live in areas with water scarcity are likelier to have a long-term orientation.PARTHAJIT DATTA/AFP via Getty Images

Shining a light on traffic stops

A sociologist linked data from the Florida Highway Patrol on over 5 million traffic stops from 2012 through 2020 with voter-registration data for the officers involved. The researcher found that white Republican officers were likelier than white Democratic officers to search Black drivers they had stopped. The researcher controlled the data to account for the county, time, and type of stop. White officers of the two parties stopped drivers of both races at similar rates; the partisan disparity was seen only in searches. Black and Hispanic officers didn’t exhibit the same partisan disparity. Although the white partisan disparity stayed relatively constant, white officers of both parties exhibited increasing disparity in stopping Black drivers from 2016 onward.


Donahue, S., “The Politics of Police,” American Sociological Review (forthcoming).

Rent at the margin

Economists at the University of Notre Dame worked with a homelessness prevention program in Santa Clara County, Calif. (which includes much of Silicon Valley, where rent levels can make those in Boston look reasonable) to conduct a randomized controlled trial of short-term financial assistance. The program typically paid several thousand dollars to landlords to cover a month or two of rent for people at risk of eviction. Renters who barely met the program’s eligibility criteria and were likely ineligible for similar assistance were randomly assigned to receive an offer of assistance. Over the subsequent year, most of their risk of becoming homeless — as measured by use of temporary shelters and street outreach — was mitigated.

Phillips, D. & Sullivan, J., “Do Homelessness Prevention Programs Prevent Homelessness? Evidence From a Randomized Controlled Trial,” Review of Economics and Statistics (forthcoming).

Foreign relations

In the United States, bans on first-cousin marriage proliferated in the latter half of the 19th century and the early 20th century (though many states, including Massachusetts, never banned it). To examine the effect of such bans on socioeconomic mobility, researchers analyzed census data on men whose surnames had historically high rates of same-surname marriages, compared with other men from the same state and generation. Bans on first-cousin marriage induced men with high-cousin-marriage surnames to move off farms, across states, and into cities, and to work in higher-paying occupations, because of weaker kinship ties. (Fun fact: The idea of using same-surname marriages as a proxy for the cousin-marriage rate originated with George Darwin, whose father Charles had married his first cousin.)


Ghosh, A. et al., “Economic Consequences of Kinship: Evidence From U.S. Bans on Cousin Marriage,” Quarterly Journal of Economics (forthcoming).

Dry future

Researchers surveyed students at universities in Yazd and Shiraz, two ethnically Persian, Shia Muslim cities in Iran with similar climates except that Yazd gets a lot less rain than Shiraz. Students in the dry city had a more long-term orientation and were less self-indulgent. This cultural difference was also seen in applications to job listings: People from the dry city were more likely to apply to an established company with job security, while people from the wet city were more likely to apply to a startup that offered flexible work. Likewise, an experiment at the University of Tehran found that students who read a scientific article predicting severe water shortages subsequently reported higher long-term orientation and lower indulgence. This pattern was also seen across the world, as people in countries with less fresh water per capita reported higher long-term orientation and lower indulgence, even controlling for other climate, agricultural, geographical, and socioeconomic factors. The authors believe “a long history of water scarcity instills in people a need to conserve, restrain indulgence, and focus on the long term.”


Harati, H. & Talhelm, T., “Cultures in Water-Scarce Environments Are More Long-Term Oriented,” Psychological Science (forthcoming).

‘Bad’ research

Sometimes, findings from social-science research can be interpreted as unfavorable to a particular social group or as favorable to an offensive behavior. In many of these instances, the authors and editors of these studies are pressured to retract, censor, or somehow atone for the publication of such research. To elucidate the underlying psychology of this pressure, a group of social scientists showed excerpts from actual published studies to nationally representative samples of Americans. These studies could be interpreted as discouraging female mentorship, disproving racial bias in police shootings, associating Christianity with racial prejudice, finding no harm from same-sex-couple parenting, or questioning harm from child sexual abuse. People who tended to overestimate the extent to which the public would blindly accept these interpretations were also more likely to support censoring science in general.

Clark, C. et al., “Harm Hypervigilance in Public Reactions to Scientific Evidence,” Psychological Science (forthcoming).