Now his team has evidence that the brains of neighboring Tsimane and Moseten may age more slowly than yours, mine, and the brains of nearly everyone in the industrialized world. “Something in lifestyle affects brain aging,” Kaplan says. He thinks he knows what that something is and can teach us how to better control the aging of anyone’s brain.
Public health in distant societies could inform public health elsewhere. In the 1980s, Kaplan worked with the Mashiguenga, an indigenous group who had only recently come into contact with industrialized Peruvian society. As Kaplan observed their lives and conducted interviews, people often came to him for help with health issues. But the young professor of anthropology had no medical training.
So he asked a colleague, doctor Benson Daitz, to come in for checkups. Daitz flew to Peru in 1987 and diagnosed patients with a litany of infections. But he was surprised by what he didn’t find. He heard no murmurs or other heart problems. The Mashiguenga had healthy hearts and blood pressure even in old age. Kaplan concluded that they could be spared many chronic diseases. This intuition stayed with him.
Three decades later, Kaplan still makes the connection between lifestyle and chronic disease, and he still provides health care in the villages that host and work with his team. The inhabitants of the villages have their medical needs met; researchers, in turn, learn about heart and brain disease.
Over the years, Kaplan’s team has reported that, like the Mashiguenga, the Tsimane have higher than average rates of infection but lower rates of heart disease and diabetes than people in the United States and Europe. “These were not conditions associated with aging,” says Daniel Eid Rodriguez, a biomedical researcher at the Universidad Mayor de San Simón, Bolivia, who has worked with Kaplan and the Tsimanes since 2004. These heart-healthy people were not not isolated cases either, says Rodriguez. “The Tsimane lifestyle seemed like the healthy recipe.”
On the other hand, a majority of people in the United States today die of the diseases of aging. Heart disease, cancer, hypertension, diabetes and Alzheimer’s disease accounted for 56% of deaths in the United States in 2019. The problem is that industrialized societies are an unnatural environment for humans, full of calories cheap and opportunities to be idle.
Kaplan’s team wanted to see if unindustrialized versus modern, industrialized living would also benefit the brain. For their latest article, published in March, Kaplan continued its ongoing partnership with the Tsimane and began a new one with the neighboring Moseten, a rural indigenous group who farm more and are more involved in modern markets than the Tsimane. The Moseten rely less on hunting and gathering, which means they don’t have to work as much for their food. All of the participants the team studied were over 40, because that’s when scientists expect the brain to age most noticeably.