The gap between rich and poor has widened in the United States for decades. Such inequality, according to experts, is detrimental to the health of all. It erodes social cohesion and creates stress and insecurity which can lead to greater risk-taking.
In many countries, this economic inequality has negative consequences for health and well-being. But is the association limited to industrialized countries with strong inequalities, where health is largely affected by chronic non-communicable diseases such as heart disease, diabetes and cancer?
In an article published in the scientific journal eLife, a team of researchers from UC Santa Barbara, Washington State University and the University of Zurich studied the relationship between economic inequalities and health among the Tsimane, a population native of relatively egalitarian horticultural gatherers in the Bolivian Amazon.
The Tsimane live in small remote villages of 50 to 500 people. Villages have few rulers, and even these have limited authority. Their active lifestyle – based on farming, fishing, hunting and gathering – allows groups of families to largely provide for their own livelihood. But the last few decades have seen rapid changes.
Many Tsimane now sell crops or timber or are involved in wage labor. And as cash flow increases, so does economic inequality.
“In all the villages the inequalities range from low – think Denmark – to high – think Brazil,” said lead author Michael Gurven, professor of anthropology at UCSB, director of the anthropological sciences unit campus integrative and co-director of Tsimane Health and Life. History project.
For the study highlighted in eLife, researchers tracked 13 measures of health and well-being over a period of up to a decade in 40 Tsimane communities. They assessed whether and how the degree of income inequality in each community was associated with one of their health measures.
Although it has been suggested that the effects of health inequalities may be universal, only two significant health impacts stood out: higher blood pressure and respiratory disease.
For several health variables, including body mass index, gastrointestinal disturbances, and depression, the researchers found no clear link to economic disparities.
However, in communities with high inequality, many had higher blood pressure, whether at the top or bottom of the economic ladder compared to their peers in less stratified communities.
Blood pressure was highest among poor men in Tsimane, no matter where they lived, although hypertension was still rare in most adults.
The study was conducted before the coronavirus pandemic, so the impacts of COVID-19 were not included, but the researchers found that greater inequality was also associated with a higher risk of respiratory diseases such as flu and pneumonia.
The authors do not know what the exact mechanisms of this connection might be, but they note that the effect is not due to psychological stress. “It is worth understanding because respiratory illnesses are the most important cause of morbidity and mortality among the Tsimane,” said Gurven.
Overall, however, inequality has had inconsistent effects on other measures of health.
“The link between inequalities and health is not as straightforward as what you typically see in the industrialized West,” said co-lead author Aaron Blackwell, associate professor of anthropology at State University from Washington. “Our results suggest that at this scale, inequality is not at the level that causes systemic health problems.”
Gurven added: “What matters most is your own income and access to resources. All these changes sweeping the territory of Tsimane lead to a rapid growth of inequalities. Those who live near roads or a short canoe ride from town see more of the bling.
But while running the status treadmill increases stress, Tsimane is still physically active, has no McDonalds, and is intensely social. Heart disease and diabetes are rare.
These conditions, he commented, protect Tsimane from the more harmful effects seen elsewhere.
“If you feel like you’re worse off than the rest, it’s stressful,” said co-lead author Adrian Jaeggi of the University of Zurich. “In Western countries, this feeling is associated with poor health – including high blood pressure, cardiovascular issues, and infectious disease, as COVID-19 has shown.
“In Tsimane communities, the effects of living in a more egalitarian community are less universal.
Blackwell and Jaeggi began this research project with Gurven while working as postdoctoral fellows at UCSB. They harnessed many types of data collected by the Tsimane Health and Life History Project to perform the most comprehensive test to date of the health inequality hypothesis in a subsistence society.
“I think this study tells us that there are reasons why inequality is bad for us, even in relatively egalitarian societies without huge economic differences,” Blackwell said.
“With increasing media exposure and better access to wealthier neighboring populations, Tsimane’s perceptions of their own status may soon change – perhaps for the worse,” Gurven said. “Comparing themselves to neighboring groups might change their idea of wealth to include fancy clothes, motorcycles and wads of cash to spend.
“If the healthy lifestyle of the Tsimane changes along with the growing gap between the haves and have-nots,” he added, “the detrimental effects of inequality will be a problem.”