Adult knowledge of wild plants associated with limited delayed health and nutritional benefits for children or adults in the face of external change: A yearly panel (2003−2010) study among Tsimane’, an indigenous Amazonian society in Bolivia

Cross-sectional studies suggest that local ecological knowledge (LEK) helps humans cope with their environment. Among the forms of LEK, adult knowledge of wild plants has been associated with better child and adult health. We assess if the concurrent links between i) LEK and ii) health and nutritional status last and examine if LEK yields delayed benefits when societies face large socioeconomic and environmental changes. We use a yearly panel (2002−2010) from Tsimane’, an Indigenous Amazonian society (Bolivia). All adults (∼440) and children (∼300) measured at baseline (2003) in 13 villages were followed yearly during 2004–2010 to estimate associations between a) baseline adult knowledge and skill about uses of wild plants and b) subsequent (2004–2010) anthropometric markers of nutritional status of themselves and the children (2y ≤ age ≤ 10y) living in the household at baseline. Among children, HAZ, BMI, and sum of four skinfolds were measured; among adults, BMI, sum of four skinfolds, and percent body fat with bioelectrical impedance were measured. Some skill losses increased by a large amount the likelihood of severe childhood stunting (HAZ < -3) for girls; the complete loss of these skills increased the share of severely stunted girls from 5% to 13%–20%. These are big numbers. The effects of LEK on other anthropometric indicators of children or adults were small. For example, if all adults in a household lost all their ethnobotanical knowledge, children's and women's BMI would decrease by only 3% and 11%, respectively.