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Traditional plant knowledge gives health boost: study

March 19, 2007
Courtesy PNAS
and World Science staff

For tra­di­tion­al cul­tures not yet drawn in­to the whirl­wind of mo­der­ni­ty, knowl­edge of lo­cal plants may pro­vide a real health boost, a study has found. 

The re­search con­clud­ed that such knowl­edge, far from be­ing a set of old wives’ ta­les, may be a use­ful body of wis­dom that’s un­der threat as glob­al­iza­tion grad­u­al­ly erases in­dig­e­nous cul­tures.

A Tsi­mane' wom­an pro­cesses maize to make chi­cha, a pop­u­lar fer­mented drink. (Cour­te­sy Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces)

Work­ing with in­dig­e­nous Am­a­zo­ni­an Tsi­ma­ne’ peo­ple in Bo­liv­ia, sci­en­t­ists found that moth­ers with good know­l­edge of lo­cal plants and their uses were like­lier than oth­ers to have healthy chil­dren.

The Tsi­mane’ live a tra­di­tion­al life­style and use lo­cal plants for fire­wood, con­s­t­ruc­tion, tools, food, and med­i­cine. As they come in­to con­tact with com­mer­cial goods and ser­vic­es, their knowl­edge of lo­cal plants fades, ac­cord­ing to the re­search­ers, Thom­as Mc­Dade of North­west­ern Uni­ver­si­ty in Ev­ans­ton, Ill. and col­leagues.

They in­ter­viewed Tsi­ma­ne’ par­ents to test their knowl­edge of lo­cal plants. The re­search­ers al­so as­sessed Tsi­mane’ chil­dren’s health us­ing mea­sure­ments of a blood mark­er, height and skin­fold thick­ness—a fold of skin formed by pinch­ing the skin and un­derlying lay­ers, which pro­vides an es­ti­mate of body fat lev­els.

The sci­en­tists found that moth­ers with less knowl­edge of lo­cal plants were more like­ly to have chil­dren with com­pro­mised health. The link was con­sist­ent across the three health meas­ures, which rep­re­sent growth, nu­tri­tional sta­tus, and lev­els of in­fec­tious dis­ease, they said. Oth­er fac­tors were al­so ex­am­ined, such as the pro­x­i­mi­ty of wa­ter sources and tra­di­tion­al heal­ers. 

Ex­act­ly how ma­ter­nal cul­tur­al knowl­edge pro­tects child health is un­known, but the re­sults high­light the im­por­tance of pre­serv­ing as­pects of tra­di­tion­al cul­ture as so­ci­eties adapt to glob­al­iza­tion, Mc­Dade and col­leagues ar­gued.

“Like many re­mote, ru­ral pop­u­la­tions around the world, the Tsi­mane’ have lim­it­ed re­sources and op­por­tu­ni­ties for ac­quir­ing food, med­i­cine, or oth­er pro­cessed goods. They re­ly heav­i­ly on lo­cal nat­u­ral re­sources... and ac­cu­mu­lat­ed knowl­edge passed down across gen­er­a­tions,” they wrote in this week’s ear­ly on­line edi­tion of the re­search jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces, where the study ap­peared.

Glob­al­ly, educa­tion and eco­nom­ic se­cu­ri­ty are key de­ter­mi­nants of health, they wrote. But when both are lim­it­ed, as they are for the Tsi­mane’, then lo­cal knowl­edge plays a ma­jor role, they added—and its loss may come at a sig­nif­i­cant cost.

* * *

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For traditional cultures not yet drawn into the whirlwind of modernity, knowledge of local plants may provide a real health boost, a study has found. The research concluded that such knowledge, far from being a collection of old wives’ tales, is a useful body of wisdom that’s under threat as globalization gradually erases indigenous cultures. Working with indigenous Amazonian Tsimane’ people in Bolivia, the scientists found that mothers with good knowledge of local plants and their uses were more likely to have healthy children than those lacking such understanding. The Tsimane’ live a traditional lifestyle and use plants from local sources for firewood, construction, tools, food, and medicine. But as the Tsimane’ come into contact with commercial goods and services, their knowledge of local plants decreases, according to the researchers, Thomas McDade of Northwestern University in Evanston, Ill. and colleagues. They interviewed Tsimane’ parents to test their knowledge of local plants. The researchers also assessed the health of Tsimane’ children using measurements of a blood marker, height and skinfold thickness—a fold of skin formed by pinching the skin and underlying layers, which provides an estimate of body fat levels. The scientists found that mothers who had less knowledge of local plants were more likely to have children with compromised health. The link was consistent across the three health measures that represent child growth, nutritional status, and levels of infectious disease, they said. Other factors were also examined, such as distance of home to a water source or presence of ethnomedical healers. Exactly how maternal cultural knowledge protects child health is unknown, but the results highlight the importance of preserving aspects of traditional culture as societies adapt to globalization, McDade and colleagues argued. “Like many remote, rural populations around the world, the Tsimane’ have limited resources and opportunities for acquiring food, medicine, or other processed goods. They rely heavily on local natural resources to meet their daily needs and accumulated knowledge passed down across generations,” they wrote in the this week’s early online edition of pnas, where the study appeared. Globally, education and economic security are key determinants of health, they wrote—but when both are limited, as they are for the Tsimane’, then local knowledge plays a major role. Then, the authors added, “the loss of adaptive cultural resources for protecting health may come at a significant cost.”