Among people in the United States and other westernized countries, blood pressure readings tend to rise with age. But a new study suggests that's not true for the Yanomami, a tribe of hunter-gatherer-gardeners living in a remote Venezuelan rain forest.

Researchers measured blood pressure in 72 Yanomami people and 83 people from a nearby tribe, the Yekwana. The people ranged in age from 1 to 60 years old. The Yekwana have been slightly "westernized," thanks to missionaries and an airstrip that allows for occasional deliveries of processed food and salt.

The Yanomami had no age-related rise in blood pressure. But the Yekwana's blood pressure readings began rising during childhood — by about a quarter of a point per year, on average. As the authors suggest, "a rise in blood pressure may not be natural but rather a consequence of unnatural Western exposures." The study was published online Nov. 14,