Violence among foragers: The bioarchaeological record from central California

Spatial and diachronic patterns in skeletal evidence for three forms of violence were evaluated for central California with information from a bioarchaeological database that contains information on 16,820 burials from 329 sites. The most abundant form of violence was sharp force/projectile trauma (462/6278, 7.4%), followed by blunt force craniofacial trauma (264/6202, 4.3%) and trophy-taking/dismemberment (87/12,603, 0.7%). Signs of violence were concentrated in the area with the highest ethnographic population densities (Sacramento River), but also in the southern San Francisco Bay area which seems to have been a contested interface zone between established residents and incoming migrants. Sharp force/projectile trauma was also high in the Sierra Nevada following introduction of the bow and arrow, and violence in general was more common among males, although there is less of a sex-difference among individuals with blunt force craniofacial injuries in central California relative to southern California, suggesting greater participation by females in this form of violence as attested by historic eyewitness accounts. Temporal patterning shows two episodes of elevated violence: the Early Middle Period (500 cal B.C.–cal A.D. 420) when trophytaking/dismemberment peaked, and the Protohistoric/Historic Period (cal A.D. 1720–1899) marked by high levels of blunt force craniofacial and projectile trauma. The Protohistoric/Historic peak, preceded by the appearance of the bow and arrow ca. A.D.1000–1200 and an associated upturn in projectile violence, is attributed to the arrival of Europeans into southwestern North America 250 years before their permanent settlement in California ca. A.D. 1769

Staple, Feasting, or Fallback Food? Mussel Harvesting Among Hunter-Gatherers in Interior Central California

Shells are a visible component of archaeological middens in Central California. While coastal and bay shore sites are often dominated by shells, these food items were sometimes hauled many kilometers from their collection points and are found in appreciable numbers in inland sites as well. Using oxygen and carbon stable isotope data from 44 Mytilus sp. (mussel) shells, we reconstruct shellfish seasonality harvesting at one inland site dating to the Middle Period (ca. 2500-1000 cal yrs BP), CA-SOL-364. Data show that shells were collected from nearby Suisun Marsh and were harvested almost exclusively during winter, a pattern that contrasts with coastal and bay shore sites. Such a harvesting signature is unlike that expected for a food staple or a feasting resource. We suggest mussels were harvested as a fallback food, as a source of protein or micronutrient to complement carbohydrate-rich foods that were stored and consumed during winter, or perhaps were only exploited as opportunity costs relaxed during winter, making sessile mussels an attractive subsistence pursuit

Resource scarcity drives lethal aggression among prehistoric hunter-gatherers in central California

The origin of human violence and warfare is controversial, and some scholars contend that intergroup conflict was rare until the emergence of sedentary foraging and complex sociopolitical organization, whereas others assert that violence was common and of considerable antiquity among small-scale societies. Here we consider two alternative explanations for the evolution of human violence: (i) individuals resort to violence when benefits outweigh potential costs, which is likely in resource poor environments, or (ii) participation in violence increases when there is coercion from leaders in complex societies leading to group level benefits. To test these hypotheses, we evaluate the relative importance of resource scarcity vs. sociopolitical complexity by evaluating spatial variation in three macro datasets from central California: (i) an extensive bioarchaeological record dating from 1,530 to 230 cal BP recording rates of blunt and sharp force skeletal trauma on thousands of burials, (ii) quantitative scores of sociopolitical complexity recorded ethnographically, and (iii) mean net primary productivity (NPP) from a remotely sensed global dataset. Results reveal that sharp force trauma, the most common form of violence in the record, is better predicted by resource scarcity than relative sociopolitical complexity. Blunt force cranial trauma shows no correlation with NPP or political complexity and may reflect a different form of close contact violence. This study provides no support for the position that violence originated with the development of more complex hunter-gatherer adaptations in the fairly recent past. Instead, findings show that individuals are prone to violence in times and places of resource scarcity

Resource scarcity drives lethal aggression among prehistoric hunter-gatherers in central California

The origin of human violence and warfare is controversial, and some scholars contend that intergroup conflict was rare until the emergence of sedentary foraging and complex sociopolitical organization, whereas others assert that violence was common and of considerable antiquity among small-scale societies. Here we consider two alternative explanations for the evolution of human violence: (i) individuals resort to violence when benefits outweigh potential costs, which is likely in resource poor environments, or (ii) participation in violence increases when there is coercion from leaders in complex societies leading to group level benefits. To test these hypotheses, we evaluate the relative importance of resource scarcity vs. sociopolitical complexity by evaluating spatial variation in three macro datasets from central California: (i) an extensive bioarchaeological record dating from 1,530 to 230 cal BP recording rates of blunt and sharp force skeletal trauma on thousands of burials, (ii) quantitative scores of sociopolitical complexity recorded ethnographically, and (iii) mean net primary productivity (NPP) from a remotely sensed global dataset. Results reveal that sharp force trauma, the most common form of violence in the record, is better predicted by resource scarcity than relative sociopolitical complexity. Blunt force cranial trauma shows no correlation with NPP or political complexity and may reflect a different form of close contact violence. This study provides no support for the position that violence originated with the development of more complex hunter-gatherer adaptations in the fairly recent past. Instead, findings show that individuals are prone to violence in times and places of resource scarcity