We walk through the rainforest in Bolivia with Martina Kanči Neitl, while red butterflies fly around, and we ask her to stop because our team is not able to keep up with her.
Her ID card shows that she is 84 years old, but within 10 minutes she can dig up three rhizomes of a woody yucca plant and cut down a banana tree in just two moves.
She puts a huge pile of fruit on her back and heads home from the plot where she grows cassava, corn, bananas, and rice.
Martina is one of the 16.000 Chiman, a semi-nomadic indigenous people who live deep in the Amazon rainforest, 600 kilometers north of Bolivia's capital, La Paz.
Her strength is not unusual for a Čimana of her age.
Scientists have concluded that members of this community have the healthiest arteries of any studied so far and that their brains age more slowly than the brains of people in North America, Europe and other parts of the world.
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There are very few Chimans.
They are one of the last peoples on the planet who deal exclusively with hunting, searching for food and growing crops.
At the same time, there are enough of them to be a significant scientific sample.
The researchers, led by anthropologist Hillard Kaplan of the University of New Mexico, have been studying this people for two decades.
They spend only 10 percent of daylight hours in sedentary activities, and industrial society 54 percent.
An average hunt, for example, lasts more than eight hours during which they cover 18 kilometers.
They live on the banks of the Manikia River, about 100 kilometers by boat from the nearest town, and it is difficult for them to reach places where they can get processed food, alcohol and cigarettes.
Researchers found that only 14 percent of calories are from fat, while residents of the United States (USA) more than double that, 34 percent.
Since their diet is rich in fiber, they get 72 percent of their calories from carbohydrates, and the residents of the USA get 52 percent.
They get their protein from animals they hunt, such as birds, monkeys and fish.
Foods are never fried.
The first work of Professor Kaplan and his colleague, Michael Gurven of the University of California, Santa Barbara, was anthropological in nature.
But they noticed that older Chimans did not show signs of diseases typical of old age, such as high blood pressure, diabetes and heart problems.
Then a study published in 2013 caught their attention.
A team led by American cardiologist Rendal S. Thomson used computed tomography (CT) to examine 137 mummies from the ancient civilizations of Egypt, the Incas and the Aleuts.
As people age, the buildup of fat, cholesterol, and other substances can lead to thickening and hardening of the arteries, which causes the disease atherosclerosis.
They found such signs in 47 mummies, which calls into question the assumptions that the cause of such conditions is the modern way of life.
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Two research teams joined forces and scanned 705 Chimans with a computerized tomography device to determine the calcium score - the presence of plaque in the coronary arteries, the value of which is important for assessing heart attack risk.
Their study, which was first published in the scientific journal Lancet in 2017, showed that 65 percent of Chimans over 75 had a calcium score of zero, or more precisely, that they did not have plaque.
By comparison, most Americans of that age (80 percent) have plaque in their arteries.
"The arteries of a 75-year-old Chiman look like the arteries of a 50-year-old American," says Kaplan.
In the second phase of the research, the findings of which were published in 2023 in the professional journal of the US Academy of Sciences (Proceedings of the National Academy of Science), found that older Chimans have up to 70 percent fewer signs of brain atrophy than people of the same age in industrialized countries such as the United Kingdom (UK), Japan, and the USA.
"We haven't found Alzheimer's disease in any adult Chiman - that's amazing," Bolivian doctor Daniel Eid Rodríguez, medical research coordinator, tells us.
However, it is not easy to determine the age of members of the Chiman people.
Some do not know how to count, so they cannot count their years.
They told us that they are guided by records of Christian missions in the area or years of acquaintance with members of their community.
Scientists calculate years based on the age of children.
According to their records, Hilda is 81 years old, but says that recently her family killed a pig for her "100th" birthday celebration. years or about a hundred".
Juan, who says he is 78 years old, takes us hunting.
His hair is dark, his eyes are lively, and his arms are muscular and firm.
We watch as he stalks a small hairy wild boar that manages to sneak through the bushes and escape.
He admits that his legs are getting heavy: "My body is betraying me. I can no longer walk for so long... two days at most".
Martina agrees.
Members of the Chiman people are known for weaving roofs from plants from the palm family (Geonoma deversa), which grows deep in the rainforest.
In order to find her, Martina has to walk for three hours in one direction, and on the way back she has to carry branches on her back.
"I do it once or twice a month, although it's harder now," she says.
However, many Chimans do not live to old age.
At the beginning of the study, the average life expectancy was barely 45 years, but now it has risen to 50.
As he prepares the elderly women for a CT scan at the clinic where this examination is performed, Dr. Eid inquires about their families.
One, counting on her fingers, sadly says that she had six children, five of whom died.
Another says she had 12, four of whom died, and the third says she has nine children who are alive, but three of them died.
"People who have reached the age of 80 are those who managed to survive childhood, because then the members of this community are exposed to many diseases and infections," explains Dr. Eid.
Researchers believe that all Chimans had some kind of parasite or worm infection during their lives.
They also discovered a high level of pathogens and various inflammations, which indicates that Chiman's bodies are constantly fighting infections.
Because of this, they wondered if these infections at an early age, in addition to nutrition and physical activity, are another reason for the good health of the elderly Chimans.
However, the way of life of this community is changing.
Juan says he hasn't been able to catch a big enough animal for months.
In the wave of forest fires at the end of 2023, almost two million hectares of rainforests and forests were destroyed.
"The animals ran away from the fire," he says.
He has started raising cattle and shows us four bulls that he hopes will provide protein for his family this year.
Dr. Eid says that boats with outboard motors, known as peke-peke (peque-peque).
With it, the Čimani travel to places where they can get sugar, flour and oil.
And since the boats have a motor drive, it means that they row less than before, which is "one of the most demanding physical activities," he says.
20 years ago, there were almost no cases of diabetes, but this disease began to appear, and cholesterol levels began to rise even among younger people, researchers discovered.
"Every small change in their lifestyle affects these health parameters," says Dr. Eid.
During 20 years of scientific work, the researchers themselves have influenced the lives of this people, because they have provided them with better access to health care - from cataract operations to the treatment of broken bones and snake bites.
But he tells Hilda that old age should not be taken too seriously.
"I'm not afraid of death," he tells us with a smile.
"They will bury me and I will not move, I will lie still".
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