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The History and Archaeology of Yerba Buena Island - Prehistory

Lifeways of the Native Americans of San Francisco Bay
and Yerba Buena Island

9,000 - 5,000 YEARS AGO
People were certainly living in the greater Bay Area at least 9,000 years ago, but no archaeological sites that old have been discovered on the Bay itself. They seem to have been submerged by the rising sea level or buried by the silt and sediments that washed into the valleys and bays. Archaeologists have found occupation sites 5,000 years old along the Bay margins. The inhabitants were foragers who moved at various times of the year as seasonal foods became available in different places. They collected a variety of plant foods including pine nuts and acorns and used millingslabs and handstones to grind them. They used darts tipped with stone points and throwing sticks called atlatls to hunt. They caught fish and birds and collected shellfish along the shores of the Bay.

map 5,000 - 2,500 YEARS AGO
The population of the area continued to increase, and large permanent villages began to appear around San Francisco Bay. A new ground stone technology developed-the mortar and pestle (ground stone is stone shaped by pecking and grinding). Residue from oysters and mussels, jacksmelt, sturgeon, and shark vastly outweigh the bones of terrestrial mammals in the one well-studied archaeological site from this period. Rectangular shell beads and round abalone ornaments are found in archaeological sites of this age. These items suggest increased regional trade as people made the transition to a more settled life. Native People began using Yerba Buena island about 3,500 years ago using tule boats to get there from the mainland.

2,500 - 1,600 YEARS AGO
Some kind of cultural shift took place about 2,500 years ago. Rectangular shell beads which had been used for 3,000 years dropped out of use and new rounded shell beads became popular. Also, the number of long-term residential villages increased dramatically around the Bay. The residents began storing large amounts of acorns and other large nuts and seeds. They hunted large mammals such as harbor seals, tule elk, and black-tailed deer, while continuing to harvest mussels and oysters.

1,600 - 950 YEARS AGO
A new people from the Central Valley-called the Meganos culture by archaeologists-came into the valleys east and south of San Francisco Bay about 1,600 years ago. Although they did not take over the shoreline villages around the Bay itself, their arrival somehow triggered the acceptance of new bone tool types, including fish spears, whistles, and awls used for making coiled baskets. Saddle-shaped shell beads replaced circular forms. Mica ornaments appeared, as well as new types of abalone ornaments. Some archaeologists suggest that this new culture arose as a result of overpopulation and warfare.