Indigenous Knowledge Networks in the Face of Global Change

Indigenous knowledge networks in the face of global change Rodrigo Cámara-Lereta,1, Miguel A. Fortunab, and Jordi Bascompteb aIdentification and Naming Department, Royal Botanic Gardens, Kew, Richmond TW9 3AE, United Kingdom; and bDepartment of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland Edited by Rodolfo Dirzo, Department of Biology, Stanford University, Stanford, CA, and approved April 3, 2019 (received for review January 7, 2019) Indigenous communities rely extensively on plants for food, shelter, biodiversity hotspots (Fig. 2A). We focus on palms (Arecaceae), and medicine. It is still unknown, however, to what degree their one of the most economically important plant families in the survival is jeopardized by the loss of either plant species or tropics (15), which provide essential ecosystem services to in- knowledge about their services. To fill this gap, here we introduce habitants in our study area (14). During 18 mo of fieldwork, indigenous knowledge networks describing the wisdom of indige- interviews were conducted with inhabitants from 57 communities nous people on plant species and the services they provide. Our about the services forest palms provide, following a standard results across 57 Neotropical communities show that cultural heri- protocol (16). Communities knew a range of 7–41 palm species tage is as important as plants for preserving indigenous knowledge (mean ± SD, 17.8 ± 8.4 species) and 12–94 palm services both locally and regionally. Indeed, knowledge networks collapse as (mean ± SD, 36.4 ± 18.5 services; SI Appendix, Table S1). These fast when plant species are driven extinct as when cultural diffusion, services span the hierarchy of human needs from human nutri- either within or among communities, is lost. But it is the joint loss of tion and medicine to ritual and spiritual needs (Fig. 1) (17). plant species and knowledge that erodes these networks at a much We start by addressing how biological and cultural heritage higher rate. Our findings pave the road toward integrative policies jointly influence the structure of indigenous knowledge networks that recognize more explicitly the inseparable links between cultural across our study area. We do so by decomposing the total dis- and biological heritage. similarity in knowledge networks for every pair of indigenous communities (β) into the components of plants and services (node ECOLOGY ecosystem services | network science | tropical ecosystems | turnover; βbio) and indigenous knowledge turnover (link turnover; biocultural diversity | indigenous societies βcul), respectively (18) (Fig. 3A). In addition, we calculated the relative importance of each component, dividing each component ndigenous communities of tropical regions have assembled of turnover by the overall turnover, to indicate to what extent Isophisticated knowledge about plants and their services (1–3), knowledge networks are mainly shaped by the biological or cul- which has significantly enhanced local livelihoods (4) and global tural heritage of indigenous communities. We found that total economies (5, 6) (Fig. 1). Unlike the burning of the Library of dissimilarity in knowledge increases linearly with the turnover in SCIENCE Alexandria, however, the knowledge acquired by nonliterate plants and services (nodes). Indigenous knowledge (link) turnover SUSTAINABILITY – societies may vanish in silence (7 10). Recently, platforms such was weakly related to turnover in species composition, highlighting as the Intergovernmental Science-Policy Platform on Biodiver- that turnover in cultural preferences adds complementary in- sity and Ecosystem Services have recognized the need to information to understanding total network dissimilarity. Our results corporate into science assessments and policy the underexplored show that communities share only moderate amounts of knowl- role that culture plays in enhancing the beneficial contributions edge, even about shared species. Notably, we found that the of nature to people (11–13). So far, however, studies of indigenous knowledge of plant services are typically affected by Significance two sets of limitations. First, these studies are based on aggregate indicators such as the number of uses, useful species, or uses per species known within a community (14), leaving out essential The knowledge of nonliterate societies may vanish in silence ’ information on the identity of species and uses and their rela- jeopardizing indigenous peoples livelihoods. Yet, this cultural tionships. Second, previous studies have generally documented component is missed by studies on ecosystem services that have knowledge at small scales or within few ethnic groups. As a re- historically emphasized the biological dimension. Here we fill sult, we miss the macroscopic insights needed to assess the re- this gap by introducing indigenous knowledge networks repre- gional turnover of knowledge and its resilience to localized loss senting the wisdom of indigenous people on plant species and of plant species and cultural heritage. Here, we fill these gaps by the services they provide. This approach allows us to assess how knowledge held by 57 Neotropical indigenous communities is addressing how knowledge about plant services held by 57 structured locally and regionally, how it is influenced by turn- Neotropical indigenous communities (Fig. 2A) is structured lo- over in biological and cultural heritage, and how the progressive cally, how it changes regionally, and how it is eroded by the loss of biocultural heritage may undermine the resilience of progressive loss of biological and cultural heritage. We do so by these communities. depicting indigenous knowledge networks as bipartite graphs, in which nodes on one set represent plant species, nodes on the Author contributions: R.C.-L., M.A.F., and J.B. designed research; R.C.-L., M.A.F., and J.B. other set represent plant services, and a link connecting a plant performed research; R.C.-L. and M.A.F. analyzed data; and R.C.-L., M.A.F., and J.B. wrote species to a service indicates that the indigenous community the paper. knows that the plant provides them that service (Fig. 2B). We The authors declare no conflict of interest. refer to links as indigenous knowledge because they convey This article is a PNAS Direct Submission. people’s discovery of a particular service provided by a given This open access article is distributed under Creative Commons Attribution-NonCommercial- plant. Our macroecological approach, in turn, allows us to link NoDerivatives License 4.0 (CC BY-NC-ND). these local knowledge networks to the regional pool of knowledge. 1To whom correspondence should be addressed. Email: [email protected]. Our study area in northwestern South America is exceptionally This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. rich in biocultural diversity: it is home to c. 110 indigenous ethnic 1073/pnas.1821843116/-/DCSupplemental. groups, the Amazon wilderness area, and the Andes and Chocó www.pnas.org/cgi/doi/10.1073/pnas.1821843116 PNAS Latest Articles | 1of6 Downloaded by guest on September 26, 2021 Fig. 1. Indigenous knowledge of plant services. Daily life in indigenous communities where palm products play a central role: (1) Macuna using Astrocaryum jauari fruits as fish bait. (2) Tikuna selling a souvenir bow made from Iriartea deltoidea stem. (3) Carijona using Iriartella setigera blowgun to hunt. (4) Edible beetle grubs from the felled and decaying stems of Bactris gasipaes. (5) Yucuna using mortar made from the stem of Bactris gasipaes to pound coca leaves that are ritually chewed. (6) Split Socratea exorrhiza stems as house walls and floors. (7) Embera house thatched with Welfia regia. (8) Cofán extracting edible oil from Oenocarpus bataua fruits. (9) Achuar eating Mauritia flexuosa fruits. (10) Tsa’chila playing the marimba instrument made from Iriartea deltoidea stems. Image courtesy of Susana Cámara-Leret (artist). relative contribution of biological and cultural heritage was simi- negatively related to the number of informants and to the fraction lar, at ∼50% (range, 0.15–0.91 and 0.09–0.85, respectively; Fig. of services in relation to the metaweb (SI Appendix,Fig.S2). Thus, 3B). In other words, variation in the realization of ecosystem keystone communities are not as defined by their species pool but, services in the study area is as strongly constrained by turnover in rather, by their people’s knowledge. We hypothesize this may be the biological and the cultural dimensions. analogous to the species–area relationship of biogeography (19), Next, we quantify to what extent the total knowledge of the whereby as human communities grow in size, their ability to ex- services provided by plants is distributed across the different in- plore nature’s services may increase, fostering more innovations. digenous communities. This serves to identify whether communi- Interestingly, communities with a similar use of shared plants do ties are equivalent in terms of their local knowledge, or whether not account for a similar proportion of the metaweb (SI Appendix, there are a few keystone communities. To do so, we first aggregate Fig. S3). Such an absence of redundancy means that in theory, the knowledge networks of all local communities to build what we both communities would have to be conserved to represent the refer to as the indigenous knowledge metaweb (i.e., the global total pool of knowledge. knowledge that communities have of the services

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