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Information on the Tsimane:
Language:Tsimane and some Spanish
Population: 6000
Subsistence: horticulture, fishing, hunting.
Government: Chief/Tribal
Religion: Indigenous beliefs

Tsimane cutting wood
Tsimane village
Monkeys are a prized food item among the Tsimane


Tsimane Anger Research Project

The Tsimane are a Native American group of foragers and horticulturalists who live in the lowlands of Bolivia along the Maniqui River.  Living in groups from 50 to 300, the Tsimane are semi-sedentary though families may spend weeks or months on hunting or field cultivation trips away from settled villages.  Tsimane engage in garden cultivation, fishing, hunting, and gathering for sustenance.  Plantains, rice, corn, and sweet manioc are grown in small swiddens.  The Tsimane still use bows and arrows and tracking dogs when hunting, as their ancesters did, though they have now acquired rifles and shotguns which are used when ammunition is available.  Monogamy is the norm though polygyny does occur at low frequencies (~10%) in more remote communities.  Land and resources are privately owned though widely shared.  Disputes over land access for horticultural purposes are common.
The Tsimane lacked formal political positions until the late-20th century, when outside political pressure led to the establishment of elected village chiefs.  These chiefs are principally representatives to outside political bodies, and they generally have short tenure and no coercive authority within their villages.  For much of Tsimane history, shamans held the highest status positions due to their ability to commune with forest spirits and ancestors (Daillant, 1994).  Shamans have all but disappeared among the Tsimane, due in part to the longstanding influence of Catholic and evangelical missionaries.

Unlike other Amazonian societies such as the Yanomamo (Chagnon, 1988) and Achuar (Patton, 2000), the Tsimane have no recent history of warfare.  Within communities, however, violence between adult males and within nuclear families is relatively common.

Michael Gurven, an Associate Professor in the Department of Anthropology, UC Santa Barbara, runs a field site among the Tsimane.  Chris von Rueden and Aaron Sell designed and conducted studies of the Tsimane to test predictions from the recalibrational theory of anger.

Ongoing projects include:
    1). Testing the role of physical strength and social status on anger and aggression.
    2). Testing mechanisms for assessing physical strength from photographs and vocal samples across cultures and language groups.

Papers that have resulted from this collaboration:
Sell, A., Cosmides, L., Tooby, J., Sznycer, D., von Rueden, C. & Gurven, M. (2009).  Human adaptations for the visual assessment of strength and fighting ability from the body and face.  Proceedings of the Royal Society, 276, 575-584.

Sell, A., Bryant, G., Tooby, J., Cosmides, L., Krauss, A., von Rueden, C. & M. Gurven (2010).  Adaptations in humans for assessing physical strength and fighting ability from the voice. Proceedings of the Royal Society,in press.

Sell, A., Tooby, J., Cosmides, L., von Rueden, C. & Gurven, M.  (in preparation). Strength and anger among the Tsimane Indians of Bolivia.

Presentations that have resulted from this collaboration:

“Formidability and the logic of anger.” UQ Evolutionary Psychology Group, University of Queensland. Brisbane, Australia, May. 2012.

Society for Personality and Social Psychology, Evolutionary Psychology Pre–Conference. Vegas, Nevada, Jan. 2010. "The evolutionary psychology of human anger."

Behavior, Evolution and Culture Speaker Series.  Organized by the UCLA Center for Behavior, Evolution, & Culture.  Sept. 2009. “An evolutionary-computational model of human anger.”

The Evolutionary Biology of Human Anger. Understanding and Reducing Aggression, Violence and Their Consequences. Organized by the Herzliya Symposium on Personality and Social Psychology, March, 2009.

The role of physical strength in anger and anger expressions.  The Evolution of Human Aggression: Lessons for Today’s Conflicts. Organized by the Barbara L. and Norman C. Tanner Center for Nonviolent Human Rights Advocacy Forum, February, 2009.

Anger’s Evolutionary Origin. UCSB Affiliates: Science Lite. February 4th 2008.

Sell, A., Tooby, J. & Cosmides, L.  Violent Yells Dissected: Physical Strength is Revealed in the Voice and Enhanced during Anger.  Human Behavior and Evolution Society, College of William and Mary, May 30th - June 3rd, 2007.

Sell, A.  Strength and Anger in Human Males.  Southern California Animal Behavior Conference, UC Santa Barbara, March, 2007.

Sell, A.  The function of anger expressions: Why does his face look like that?  International Society for Research on Aggression, University of Minnesota, July 25-29, 2006.

Sell, A. Strength and Anger: Individual differences in anger, aggression and political attitudes conform to a Paleolithic logic of aggression.  International Society for Research on Aggression, University of Minnesota, July 25-29, 2006.


Michael Gurven
Associate Professor
Department of Anthropology
University of California, Santa Barbara
Santa Barbara, CA 93106

Primary Contact for Tsimane research
Aaron Sell
School of Criminology
Griffith University, Mount Gravatt
176 Messines Ridge Road
Mount Gravatt, QLD, 4121
Christopher von Rueden
Department of Anthropology
University of California, Santa Barbara
Santa Barbara, CA 93106



Chagnon, N. (1988). Life histories, blood revenge, and warfare in a tribal
population. Science, 239, 985−992.

Daillant, I. (1994). Sens dessus-dissous: Organisation sociale et spatial des Chimanes d'Amazonie boliviane. Ph.D. dissertation, Laboratoire d'Ethnologie et de Sociologie Comparative. Universite de Paris.

Patton, J. Q. (2000). Reciprocal altruism and warfare: A case from the
Ecuadorian Amazon. In L. Cronk, et al. (Eds.), Adaptation and human
behavior: An anthropological perspective (pp. 417−436). New York:
Aldine de Gruyter.