by Elise Wachspress
After phenomenal increases in lifespans over the past century, longevity in the US has begun to head in the wrong direction. Since 2014, average life expectancy has ticked downward, from a high of 78.9 years to 78.6 last year—placing us 37th among the world’s countries, tied with Albania and more than five years behind long-lived Japan (83.7 years).
The American Academy for Family Medicine cites several causes: the opioid epidemic, increasing suicide rate, and a rise in maternal mortality. Behind these specific threats lurks a shadowy but more endemic source of reduced life expectancy: growing inequality.
As long ago as the first century, the natural philosopher Pliny the Elder recognized a connection between socioeconomic status and lifespan, citing kings, senators, consuls, priests, and performers who lived to a remarkably old age. Some reasons for the perceived disparity seem pretty obvious: lack of food, shelter, hygiene, and medical care have put poor and less educated people at a disadvantage. But the data show that social status also significantly predicts longevity. For instance, despite war and the treacherous travel involved in their diplomatic missions, our first three presidents lived to ages 67, 90, and 83 respectively, when the average US resident could expect to reach only 37. And a survey of the Academy Award nominees shows that those who won the Oscars lived four years longer than those who didn’t.
How does social adversity get inside our skin? One theory is that low social status revs up genes that control the immune response, perhaps preparing lower-status members of a community to fight infections—but at the same time making them more vulnerable to conditions caused or exacerbated by inflammation, like heart disease, cancer, diabetes, and many others.
To investigate how status might influence the immune system, a group of scientists from the US and Canada studied a population of 45 rhesus monkeys, a highly hierarchical species relatively close to us on the evolutionary “tree.” They divided the monkeys into nine groups of five, observed them over a year as rank was established within each group, then re-sorted them into new groups, placing those of similar social rank together—thus forcing an abrupt change in the individual rank of most of the monkeys.
To see how the change in social status affected the animals’ immune states, the researchers took blood samples from each. They found that the lower the social status of each monkey, the stronger was the inflammatory response engaged by their immune system.
The researchers’ clever experimental design also allowed them to see how past social status affected the monkeys’ later immune states. The researchers found that animals at the bottom of the pecking order in the first year of the study still showed immunological traces of past low status, despite their improved social position in their second communities. And though the correlation was weaker, those who enjoyed high rank the first year also suffered immunologically when resorting forced them into a lower social position.
So no matter how each of these primates started in life, being at the bottom of the social ladder was demonstrably detrimental to their immunological state, even with sufficient food, housing, and care.
Research like this is a good example of how the Duchossois Family Institute (DFI), focused on understanding how to maximize health for the greatest number of people, can help us think more deeply and productively about wellness and what it will take for all to thrive.
This work is also an illustration of the approach to training and collaboration central to the organization of the DFI. The lead authors of the paper, Jenny Tung, PhD, and Luis Barreiro, PhD, both did critical postdoctoral training at UChicago early in their still-youthful careers—much like the cross-disciplinary postdocs that will now be supported through the DFI. Though Tung (a 2019 MacArthur Fellow) is now on faculty at Duke University and Barreiro (after an appointment at the University of Montreal) is now a professor at UChicago, they continue to collaborate closely and productively.
And building on that training and collaborative spirit, they are now leading a new generation of graduate and postdoctoral students to uncover how scientific research can improve health for many across the world.
Elise Wachspress is a senior communications strategist for the University of Chicago Medicine & Biological Sciences Development office.
