In an effort to understand one of western North America's most populous regions, anthropologists catalogued signs of violence in burials between the Sierra Nevada and the San Francisco Bay from historic times to 3000 BCE, identifying a complex pattern of episodic violence.
     Chronicling 16,820 burials from 329 sites among 13 ethnographic groups, the most common type of violence was sharp-force trauma, caused by projectiles like arrows or atlatl darts - 7.2% of the sample. Another 4.3% suffered apparent blunt-force trauma to the head, while just under 1% showed evidence of dismemberment, with limbs, scalps, or heads removed after death.
     The findings illustrate periodic conflicts among California's prehistoric groups, said Dr Terry Jones, an anthropologist at California Polytechnic who co-authored the study. Jones and his colleague, co-author Al Schwitalla, initially set out to determine whether any rise in violence corresponded with the centuries-long series of droughts known as the Medieval Climatic Anomaly, which persisted from about 800 to 1350 CE. The results instead revealed spikes in violence both before and after the droughts.
     The first episode spanned from 500 BCE to 420 CE, when dismemberment and trophy-taking appeared to peak - about 2% of the burials from this period, seeming to "reflect a strategy of raiding, inter-group retribution, and mutilation for the purposes of intimidation." This early period also saw the first major increase in projectile-based violence, perhaps coinciding with the introduction of the atlatl dart-thrower. This thousand-year-span appeared to be a tumultuous time throughout all of ancient California, as many hunter-gatherer groups migrated to new grounds, and new ones arrived from the east. A particular "hot zone" during this period was the southern San Francisco Bay Area, where several cultures interfaced, overlapped, and attempted to define their boundaries in a process that "was not entirely peaceful."
     The second spike took place during the early historic period, from 1720 to 1899 CE, when injuries by sharp projectiles were far more frequent than at any other time - about 10% of the sample. "The introduction of a new weapon system - the bow and arrow - definitely changed the social and political landscape, increasing inter-group conflict," Jones said. Previous research has suggested that the bow and arrow first arrived in central California from the east, perhaps as late as 1200 CE, and likely took centuries to become used widely. The frequency of projectile injuries at this time showed up most often in the foothills of the Sierra Nevada, approaching 25% in the burials sampled there, and figuring prominently among the bands of the Sierra Miwok.
     "What is abundantly clear is that prehistoric California was populated by intelligent, skilled, anatomically modern human beings who certainly were not savages but nor were they necessarily noble - they were people - subject to the same range of emotions and behavioural responses as other human populations."

Edited from Western Digs (28 April 2014)