Anthropologists study effects of modernization on physical activity, heart disease

February 1, 2013, University of California - Santa Barbara

Heart disease continues to be the leading cause of death in the United States, and a sedentary lifestyle is often cited as a major contributing factor. Among the Tsimane, an indigenous population in the lowlands of Bolivia's Amazon basin, however, indicators of heart disease are practically non-existent –– cholesterol is low, obesity is rare, and smoking is uncommon.

That's according to researchers at UC Santa Barbara and the University of New Mexico, who have been studying hunter-gatherers and forager-horticulturists to understand how their are affected by modernization; whether that, in turn, has increased the incidence of obesity, hypertension, and other conditions related to heart disease; and how their findings might apply to adults in the U.S. Their research is highlighted in an article published today in the journal .

The simple answer, according to Michael Gurven, professor of anthropology at UCSB and lead author of the study, is that alone –– or lack thereof –– does not relate to obesity or body fat among the Tsimane, and despite a subsistence lifestyle, activity alone is unlikely to account for their relative absence of chronic disease. As Gurven noted, the research demonstrates that, although a high level of physical activity may be important in staving off and diabetes, it's unlikely to be the "" that explains why a group like the Tsimane maintains a healthy chronic disease profile.

"Indigenous populations like the Tsimane are very ," said Gurven, who is also director of UCSB's Integrative Unit and the Broom Center's Biodemography and Evolution Unit. "There are people who think physical activity alone is enough to have a . They assumed the Tsimane activity level was equal to running a marathon every day. But we did the analysis, and they aren't."

By measuring the physical activity level (PAL) of individual Tsimane men and women over 24-hour periods using a combination of spot observations and accelerometers, combined with heart rate monitors, Gurven and his team found is that while the Tsimane are, indeed, physically active –– more so than average Americans –– their PAL is not so great that it separates them from that of developed populations. "We found that while the Tsimane are more active than we are, there's a decent amount of overlap," he said. "Tsimane are not more vigorously active than athletic Americans with a high activity level. In fact, Tsimane do not spend much time in 'vigorous' activity, but instead spend a lot of time in light to moderate activity. Rather than characterizing the Tsimane as vigorously active, I'd more safely say they are not sedentary."

The researchers also examined issues related to obesity and body mass index (BMI). "One idea is that we're less active than we used to be, so we get heavier," Gurven explained. "But that's actually kind of controversial. The heavier you get, the more weight you have to move around. So even though you may be less active, you could be expending more energy. There's plenty of data that even when people are experimentally manipulated to increase their activity levels, after a three month period, their weight doesn't shift all that much. Or it shifts and goes back again."

That might be due to increased appetite and subsequent excess food intake, Gurven suggested. "Depending on your hunger levels, you might be eating more than the increase in your activity can accommodate, so you end up gaining weight. When we looked at people's BMI and levels of physical activity, we found no relationship. People with higher BMI's weren't less active than people with low BMI's."

That finding, he said, is consistent with the idea that it's not physical activity, but excess food intake that is more responsible for the "obesity epidemic" of the last several decades.

Another important finding is that physical activity does not appear to correlate with modernization, as measured by village distance to town, Spanish fluency, and formal schooling. This pattern contradicts robust findings in other areas of the world, where even short periods of socioeconomic change can radically alter activity patterns and diet, and, therefore, subsequent risk of chronic disease. "And that's not particularly surprising," he said. "Even Tsimane in the most acculturated villages, who speak Spanish and have wage labor jobs, continue to work fields, and they still fish. In addition, most jobs themselves are labor-intensive –– logging, working as ranch hands, or transporting resources from one place to another. "It's all physically active work," he said. "Modernization hasn't changed that."

However, women do not typically participate in these labor intensive jobs, and so while modernization didn't affect their activity levels, modern Tsimane women were more likely to be overweight. "Tsimane men are more physically active than women at all ages, and less likely to be overweight; and so the few cases of hypertension and other ailments characteristic of cardiovascular disease are observed more among Tsimane women than men –– a striking contrast with what is commonly observed in the U.S.," Gurven concluded.

Explore further: Hunter-gatherers and horticulturalist lifestyle linked to lower blood pressure increases

Related Stories

Hunter-gatherers and horticulturalist lifestyle linked to lower blood pressure increases

May 21, 2012
Hunter-gatherers and forager-horticulturalists who live off the land and grow what they need to survive have lower age-related increases in blood pressure and less risks of atherosclerosis, according to two new studies in ...

Testosterone low, but responsive to competition, in Amazonian tribe

March 28, 2012
(PhysOrg.com) -- It's a rough life for the Tsimane, an isolated indigenous group in Bolivia. They make a living by hunting and foraging in forests, fishing in streams and clearing land by hand to grow crops. Their rugged ...

'Universal' personality traits don't necessarily apply to isolated indigenous people

January 3, 2013
Five personality traits widely thought to be universal across cultures might not be, according to a study of an isolated Bolivian society.

Anthropologists finds high levels of omega-3 fatty acids in breast milk of Amerindian women

June 8, 2012
– Working with researchers at the University of Pittsburgh and the Cincinnati Children's Hospital, anthropologists at UC Santa Barbara have found high levels of beneficial omega-3 fatty acids in the breast milk of economically ...

Recommended for you

Americans are getting more sleep

January 19, 2018
Although more than one in three Americans still don't get enough sleep, a new analysis shows first signs of success in the fight for more shut eye. According to data from 181,335 respondents aged 15 and older who participated ...

Wine is good for you—to a point

January 18, 2018
The Mediterranean diet has become synonymous with healthy eating, but there's one thing in it that stands out: It's cool to drink wine.

Sleep better, lose weight?

January 17, 2018
(HealthDay)—Sleeplessness could cost you when it's time to stand on your bathroom scale, a new British study suggests.

Who uses phone apps to track sleep habits? Mostly the healthy and wealthy in US

January 16, 2018
The profile of most Americans who use popular mobile phone apps that track sleep habits is that they are relatively affluent, claim to eat well, and say they are in good health, even if some of them tend to smoke.

Improvements in mortality rates are slowed by rise in obesity in the United States

January 15, 2018
With countless medical advances and efforts to curb smoking, one might expect that life expectancy in the United States would improve. Yet according to recent studies, there's been a reduction in the rate of improvement in ...

Can muesli help against arthritis?

January 15, 2018
It is well known that healthy eating increases a general sense of wellbeing. Researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have now discovered that a fibre-rich diet can have a positive influence ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.