Heart disease is a major killer in both the U.S. and Europe, but it’s not the inevitable outcome of aging. That’s the conclusion of Bolivian and U.S. scientists studying the 15,000 Tsimané (pronounced chee-MAH-nay) people who have almost no signs of it.
Hundreds of studies are published on the Tsimané, not only because they are the largest traditional Amazonian group, but also because they have successfully preserved a life largely based on slash and burn horticulture ever since they kept Jesuit missionaries at bay during the 17th century. Sustained outside contact didn’t begin until the 1950s, first through Catholic priests and later, protestant evangelicals from the New Tribes Mission.
Scattered in some 80 villages along rivers in the Amazon basin, the Tsimané are active four to seven hours every day: hunting, foraging, fishing and farming. Their diet is low in fat and sugar, and they seldom smoke.
The results, published in the prestigious British medical journal the Lancet, found that Tsimané over 40 were five times less likely to have calcification, or plaque buildup in their arteries—the definitive indicator of heart disease—than participants from the U.S. Multi-Ethnic Study of Atherosclerosis (MESA).
The research calls into question a conventional wisdom linking inflammation to heart disease. “We initially thought we would find a lot of heart disease because the prevailing theory was that its origins lay in high inflammation levels and the Tsimané had raised inflammation markers,” explained study co-author Daniel Eid Rodriguez, a Bolivian medical school professor.
A tiny percentage of Tsimané are part of the one in 250 people worldwide who have a genetic defect which makes their livers unable to process cholesterol, making it impossible for them to lower its levels by diet and exercise alone. However, for most people, genetic risk is far less important than lifestyle.
The core of the Tsimané diet is high-fiber carbohydrates such as plantains, rice, corn, and fruit, as well as wild game and fish. High carb diets have been vilified by many Western diet specialists, an assumption refuted by a 2015 National Institute of Health study on high carb diets that avoid refined sugars and starches. “We can definitely reject the claim that carbohydrate restriction is required for body fat loss,” wrote lead author Kevin Hall.
Even though their hearts are the world's healthiest to date, the Tsimané face an uphill battle to maintain their traditional lives. Deforestation in Bolivia’s Amazon is accelerating and is now the highest in South America. In the villages closest to the local town, San Borja, the Tsimané typically work for wages with logging companies, illegal loggers or cattle ranchers.
Anthropologist Dr. Ben Trumble of Arizona State University said, “The access to roads and motorized canoes has dramatically increased Tsimané consumption of sugar and cooking oil. This is bringing major nutritional changes.” This has been exacerbated by government projects to increase Spanish language literacy and provide services. “These have also led to greater contact with the outside world,” explained Dr. Raul Quispe who worked in the region 10 years.
The average life expectancy for the Tsimané, according to Dr. Eid Rodriguez, is 54 years. Average family size is nine, and one in five children die in their first five years. While knowledge of local medicinal plants is declining, traditional medicine is still used to treat ailments such as infection, headache and diarrhea.
The research project works with the Tsimané to address these difficulties. Called the Tsimané Health and Life History Project, it employs a traveling team of physicians and a laboratory. “We found that as their diets changed and they did less exercise, we were seeing less transmittable diseases and more of the diseases of the modern world such as cancer and diabetes,” said Dr. Quispe.
Tsimané language teacher Marino Lero explained, “The health project has been a great boon for us. But we need get our own professionals trained to solve our problems.”
The Tsimané live in Bolivia’s most bio-diverse region, their lands covered with the remains of pre-Colombian raised fields, causeways and canals, evidence of the sophisticated manipulation of nature by their ancestors. “In contrast to the Western obsession to drain lands,” writes University of Pennsylvania archeologist Clark Erickson, “these pre-Columbian farmers intentionally expanded wetlands through earthwork construction to enhance agricultural production.”
In the 1990s the Tsimané joined a pan-indigenous organization, Central de Pueblos Indigenas del Beni, and won legal recognition of their remaining lands from the Bolivian government. They formed their own organization, the Gran Consejo Tsimané, which negotiates contracts with logging companies, conservation groups, and other governmental and non-governmental organizations.
One of their biggest challenges is the felling of valuable trees such as mahogany and tropical cedar, some of it by six legal lumber companies, but much of it illegal. “Uncontrolled forestry is almost impossible to prevent,” says environmental consultant Mirso Alacalá. “Loggers illegally chop down trees within indigenous reserves and then float them down river. They don’t even use the entire tree.”
The multiple challenges facing the Tsimané belie easy solutions. “What should the Tsimane do?” asks Dr. Eid Rodriguez. “Adapt to dominant society so they can get more services like health and education from the government? That will likely mean they will lose their traditional livelihoods and cultural benefits of their isolated life.”