Tsimane fieldsite in Bolivia
Primary Site Researchers
Michael Gurven is an associate professor of anthropology at the University of California, Santa Barbara. He has conducted fieldwork in Paraguay and Bolivia with Ache and Tsimane forager-horticulturalists since 1998.
His research has focused on problems of intra-group cooperation and collective action, and the application of life history theory to better understand the evolution of human longevity, development, health and sociality. Since 2002, he has co-directed the Tsimane Health and Life History Project with Hillard Kaplan.
The Tsimane are an Amazonian forager-horticulturalist group inhabiting lowland forests and savannahs east of the Andes in the Beni department of Bolivia. Tsimane villages are concentrated along the banks of the Maniqui River, along the Quiquibey River in the Pilon Lajas region, and in the interfluvial region between San Borja and San Ignacio de Mojos. These villages are accessible by dirt road or by river, although seasonal flooding often makes access difficult.
Latitude: 14° 35' S - 15° 30' S
Longitude: 66° 23' W - 67° 10' W
Roughly 9,000 Tsimane live in the Beni department of Bolivia, dispersed in over 80 villages. Average village size is approximately 100 individuals, but over half of all villages contain less than 50 people. The population growth rate is over 3%, due to the high fertility (the average number of live births per woman is nine births) and decreasing mortality.
Average life expectancy at birth was 43 years between 1950-89 and increased to about 50 during the period 1990-2002. Half the population is under 15 years of age.
The Tsimane language is an isolate with respect to the major language families of South America, such as Tupi-Guarani or Arawakan. The Tsimane share a similar grammar and vocabulary only with the Mosetene, who inhabit the southern and northern stretches of Tsimane territory, and who were likely members of the same group over several hundred years ago. Almost all Tsimane speak Tsimane as their primary language, but many Tsimane (especially men) now speak Spanish as well, due to recent efforts at bilingual education.
Ethnic identity and history
Although the Tsimane were exposed to Jesuit missionaries in the late 17th century, they were never successfully settled in missions. Renewed missionary efforts began in the 1950s by the evangelical New Tribes Mission, which helped create a system of bilingual schools with trained Tsimane teachers.
The opening of roads to the region in 1975 led to an increase in cattle ranchers, loggers, and other colonists in Tsimane territory, who continue to employ the Tsimane as wage laborers. In the 1990s the Tsimane joined a pan-indigenous organisation, Central de Pueblos Indigenas del Beni, and won legal recognition of their remaining lands from the Bolivian government. In 1990 the Tsimane formed their own representative governmental organisation, the Gran Consejo Tsimane.
Political and social organisation
The Tsimane live in villages composed of extended family clusters, but Tsimane communities are more fluid than static. Tsimane families often migrate between communities or spend extended periods of time in the forest engaged in hunting, fishing, or field cultivation. Only 60% of adult Tsimane live in the same village where they were born.
In recent decades, Tsimane villages have adopted a system of elected chiefs (corregidores) and other officials in larger villages for representation purposes and interaction with outside interests. Chiefs wield no real power; their main tasks are to hold and conduct meetings in the event of conflicts, help organise community labour events, and represent village interests to outsiders. These chiefs have little to no coercive authority within their villages. They are usually young or middle-aged men fluent in Spanish and with some experience dealing with Bolivian nationals.
Established in 1989, the Gran Consejo Tsimane is the sole formal political body among the Tsimane, which negotiates contracts with logging companies, conservation groups, and other governmental and non-governmental organisations.
Schooling and literacy
Most older Tsimane have little formal education but younger generations in more acculturated communities have received bilingual education at government-sponsored primary and secondary schools. By 2002, two-thirds of Tsimane villages had primary schools, with bilingually trained Tsimane teachers.
Several larger villages now have secondary education with non-Tsimane teachers, and now a majority of the remote villages have recently, since 2008, set up primary education. Adult education initiatives have also increased in recent years.
Some Tsimane additionally receive technical or religious training in the local market town of San Borja, which has a population of approximately 19,000. In general, average literacy and Spanish fluency within Tsimane villages co-vary with the villages’ distance to San Borja.
Hierarchy and kinship
Like other small-scale societies, Tsimane society is fairly egalitarian. There is little accumulated wealth among Tsimane and even with increasing market access, no consistent, robust associations with wealth inequality have been found. Differences in social status due to size or skill exist, but not even village chiefs can claim decision-making authority over others.
Elected chiefs principally act as representatives and community organisers and tend to have short tenure. Traditionally, shamans and older men wielded the most social influence in Tsimane society, but their role has been eroded with the increasing exposure of the Tsimane to national Bolivian society.
Tsimane society is organised around the extended family, within which labour and food are shared. Cross-cousin marriage and matrilocal post-marital residence followed by patrilocal residence (usually after the first child is born) are most common, but there is much variability. Polygyny, particularly sororal polygyny, exists at small frequencies (less than 10% of men are married polygynously), especially among more remote Tsimane communities.
Marriages are stable among the Tsimane, with less than 10% of marriages ending in divorce. Tsimane do not commemorate weddings with formal ceremonies but consider a pair to be married when they sleep together in the same house.
Economic practices and daily life
The Tsimane economy is based on small-scale cultivation of plantains, rice, corn, and sweet manioc, as well as fishing, hunting, and gathering wild forest products. There is a strong sense of economic independence at the level of the nuclear family and extended Tsimane household. Each adult, or husband-wife pair, maintains their own horticultural fields, although farm labour is often shared among members of extended family households, which generally consist of one to four nuclear families.
Households are also the units of food distribution, although it is not uncommon for portions of fish and game to be distributed to other nearby unrelated households. Kills are usually shared among participating hunters (and helpers), and subsequent sharing is up to the discretion of the hunter, his spouse, and to some extent, resident parents or in-laws. There are thus no normative rules governing the sharing of meat. Though people eat communally in smaller villages, few people go out of their way to invite others to partake in their meals.
The Tsimane employ both solitary and group fishing activities, especially during the dry season months from May to October. They use hooks, purchased in San Borja or from traveling merchants, bow and arrow, poisonous vines, and occasionally nets, if available. The Tsimane hunt mainly with the use of rifles or shotguns, sometimes with the use of tracking dogs, and with machetes. However, the use of bow and arrow is not uncommon, especially when ammunition is not available.
Villages vary in the extent to which family clusters are dispersed or clustered, although direct interactions with most group members on a daily basis are fairly common. High levels of visiting and sharing among members of different households are usually associated with fermented manioc beer consumption. Huge vats of fermented manioc, corn, or plantains always attract visitors from other household clusters and even other villages.
The Tsimane increasingly engage in income-generating activities, such as the sale of horticultural produce and forest products (palm thatch roofing panels) to merchants in exchange for salt, sugar, clothes and fishhooks. Many Tsimane have become financially indebted as a result of these commercial transactions. Tsimane men also sporadically engage in wage labour with loggers, cattle ranchers, or farmers.
Religion and healthcare
The Tsimane are traditionally animists who believe supernatural beings inhabit the forest and control the supply of fish and game, and also the fortune (or misfortune) of humans. While these beliefs persist, many Tsimane now espouse Christianity as their religion due to recent Catholic and Protestant Evangelical missionaries. Three of the four largest Tsimane villages contain either a Catholic Redemptorist or Evangelical New Tribes mission.
New Tribes Mission helped to establish a health post for the Tsimane in San Borja in 1989, which is still used to help provide basic medical care. Relatives of the sick are asked to work for the sick person while they recover to pay for their costs.
The Tsimane Health and Life History Project (THLHP) employs a traveling team of physicians and a laboratory, which acts to extend the reach of basic healthcare to remote Tsimane villages. The THLHP also facilitates the evacuation and treatment of Tsimane patients requiring surgery.
Principal health risks for the Tsimane include respiratory and gastrointestinal infection, fungal infections and accident-related trauma. While knowledge of local medicinal plants may be declining, traditional medicine is still used to treat infection, headache, diarrhoea and other common ailments.
Michael Gurven (2004). Economic games among the Amazonian Tsimane: exploring the roles of market access, costs of giving, and cooperation on pro-social game behavior. Experimental Economics, 7, 5-24.
Michael Gurven, Hillard Kaplan, and Maguin Gutierrez (2006). How long does it take to become a proficient hunter? Implications for the evolution of delayed growth. Journal of Human Evolution. 51, 454-470.
Michael Gurven and Chris von Rueden (2006). Hunting, social status and biological fitness. Social Biology, 53, 81-99.
Michael Gurven, Hillard Kaplan, and Alfredo Zelada Supa (2007). Mortality experience of Tsimane Amerindians: Regional variation and temporal trends. American Journal of Human Biology, 19, 376-398.
Michael Gurven and Jeffrey Winking (2008). Collective action in action: Pro-social behavior in and out of the laboratory. American Anthropologist, 110.2, 179-190.
Chris von Rueden, Michael Gurven, and Hillard Kaplan (2008). Multiple dimensions of male social status in an Amazonian society. Evolution and Human Behavior, 29.6, 402-415.
Michael Gurven, Arianna Zanolini, and Eric Schniter (2008). Culture sometimes matter: Intra-cultural variation in division norms among Tsimane Amerindians: Real or spurious? Journal of Economic Behavior and Organization, 67, 587-607.
Michael Gurven, Jeffrey Winking, Hillard Kaplan, Chris von Rueden, and Lisa McAllister (2009). A bioeconomic approach to marriage and the sexual division of labor. Human Nature, 20.2, 151-183.
Jeffrey Winking, Michael Gurven, Hillard Kaplan, and Jonathan Stieglitz (2009). The goals of direct parental care among a South Amerindian population. American Journal of Physical Anthropology, 139.3, 295-304.
Michael Gurven, Hillard Kaplan, Jeffrey Winking, Daniel Eid Rodriguez, Sarinnapha Vasunilashorn, Jung Ki Kim, Caleb Finch, and Eileen Crimmins (2009). Inflammation and infection do not promote arterial aging and cardiovascular disease risk factors among lean horticulturalists. PLoS ONE 4.8: e6590. doi:10.1371/journal.pone.0006590.