New IPR Research: March 2025
Get all our news
This month’s new research from our faculty experts examines the connection between poverty and health and how gut microbes may have fueled the evolution of larger brains. It also looks at the link between marital conversations and heart health and the impact of one-time food benefits during the pandemic.
Health Inequalities
The Connection Between Poverty and Health
Poverty is closely linked with worse health, but not all people living in poverty have poor health—it varies by where they live and the time in which they’re living. In a working paper, IPR economist Hannes Schwandt and his colleagues review evidence explaining these patterns and connections. While there is no simple relationship between income and health, the researchers cite evidence showing that poverty during a pregnancy leads to the child or children having worse health later on. Other research suggests that recent medical and technological advancements in the 20th century have increased health gaps between the rich and poor, especially in the U.S. where income and education are important to access medical care. It is also true that poor health can have negative economic consequences—both in physically demanding and less physical jobs—and cause poverty. Having less education and being part of a minority group are also closely linked to poverty rates and health. Whether your parents are poor and the income level of the neighborhood you live in also can determine the quality of your health. Recent research shows strong evidence that interventions like expanding access to healthcare and subsidizing food for low-income families can improve the health of people living in poverty in both the short and long term. The researchers call for more investigation into the ways in which poverty does and does not predict poor health and the long-term effects of anti-poverty programs.
Education and Human Development
Gut Microbes May Have Fueled the Evolution of Larger Brains
Growing and maintaining large brains requires a lot of energy, but the biological systems that make this possible are still not fully understood. Previous research has explored genetic and environmental factors, but we know less about how gut microbes—tiny organisms in the digestive system—contribute to the process. A new study in Microbial Genomics by a team of researchers including IPR anthropologist Chris Kuzawa and anthropologist and IPR associate Katie Amato suggests that gut microbes may play a key role in supporting the energy needs of bigger brains. The researchers transplanted gut microbes from humans, squirrel monkeys (both large-brain primates), and macaques (a small-brain primate) into germ-free mice. Over 60 days, they monitored changes in the mice, including weight gain, fat storage, blood sugar levels, and liver function. Mice with microbes from large-brain primates used more energy, maintained lower body fat, and had higher glucose levels, while those with microbes from macaques stored more fat and exhibited slower metabolisms. This pattern emerged even though humans and squirrel monkeys are not closely related, suggesting their shared need for large brains influenced similar microbial adaptations. These findings highlight a critical link between large-brain primates’ gut microbes and metabolic patterns favoring energy production over storage, offering new insights on the complex interplay of biology that made the evolution of humans’ large brains possible.
Marital Conversations and Heart Health
Does the way married couples express their emotions to each other matter for their health? In Emotion, developmental psychologist and IPR associate Claudia Haase and her colleagues examine how the use of “emotion words” during conversations is associated with heart functioning, focusing on interactions between married couples. Emotion words are words people use to express their feelings, whether negative, like “angry” or “frustrated,” or positive, like “happy” or “glad.” The researchers analyzed conversations between 49 mixed-sex married couples from diverse socioeconomic, racial, and ethnic backgrounds, focusing on both the frequency and diversity of emotion words used. The researchers used data collected between 2015 and 2017 from a larger research project that looked at how emotions affect married couples' relationships in the Chicago area. In a lab setting, couples had conversations, including a chat about events of the day, a conflict discussion, and a pleasant conversation, while their heart rates were monitored. The goal was to see how their emotions, expressed through their words, might relate to their heart functioning. How couples express negative emotions can be an important sign of future health risks, with higher anger behavior, for example, predicting an increased risk of developing heart problems. The study showed that using positive emotion words wasn’t significantly associated with heart rate changes, but when spouses used negative emotion words, like “angry,” their heart rates increased. This happened in both conflict and pleasant conversations, and for both husbands and wives. These findings show how the ways couples share their emotions matters for health. However, the researchers add that even though expressing negative emotions, especially anger, can raise heart rate in the moment, processing these emotions aloud may be constructive for couples over the longer term if they can address the underlying issues. This research highlights that health outcomes are interdependent and shaped by our interactions with others.
Poverty, Race, and Inequality
The Impact of One-Time Food Benefits During the Pandemic
During the first few months of the pandemic, about 27% of American households with children reported they sometimes or often couldn’t afford food. In the Journal of Public Economics, IPR economist Diane Whitmore Schanzenbach and her colleagues study how resources from the Pandemic Electronic Benefit Transfers (P-EBT) program shaped spending, food insecurity, and the health of families during the pandemic recession. One of several initiatives the government implemented to support Americans and stabilize the economy in 2020, the P-EBT program provided one-time grocery vouchers to families of children who were eligible to receive free school meals. The vouchers were roughly $300 per student and were sent on an EBT debit card to families with children who were cut off from free school meals when schools closed. To measure the impact of payments, the researchers combined biweekly data on food insecurity and household wellbeing from the Census Bureau’s Household Pulse Survey from April–Aug. 2020 with administrative state data on P-EBT spending. They find in the month after P-EBT payments were disbursed, families reported lower levels of food insufficiency, dropping by roughly 27–49%, and mothers reported better mental health. P-EBT payments were also spent across many weeks, versus SNAP assistance, which is usually spent immediately after families receive it. This shows that lump-sum assistance like grocery vouchers can benefit low-income families—especially in times of crisis—by reducing food insecurity and improving mental health.
Photo credit: Unsplash
Published: March 6, 2025.
