Use of Plants & Animals

Sudying the Plant & Animal Remains
By studying the plant and animal remains preserved in the deposits of the Emeryville shellmound we can begin to piece together what the environment was like at the time of its occupation, how the environment might have changed through time and what kinds of plants and animals were eaten or used for other purposes by the prehistoric inhabitants. The term "paleoenvironmental reconstruction" is used for studies that have the aim of helping us learn more about ancient environments and how they have changed through time.

Identifying Animal Bones
One of the specialists who worked on the shellmound project is a zooarchaeologist. This is a scientist who specializes in the identification of animal bones. Scientists have discovered that certain species of small mammals are very sensitive to climatic change. Specialists trained at identifying such animals from their skeletal remains can demonstrate relative abundance through time of certain species by looking at the number of specimens recovered from distinct strata in an archaeological site. The study of animal bones can also provide valuable information about diet, hunting patterns and availability or popularity of one species over another. In a similar fashion another specialist, known as a paleobotanist, focused on the carbonized plant remains found in the archaeological deposits.

Key Findings
The plant specialist noted that the inhabitants of the Emeryville shellmound were optimally located because they were in close proximity to three distinct environmental zones - riparian (along a water way, Temescal Creek), grassland, and wetland (along the edge of San Francisco Bay). Each of these environmental zones supported a variety of plant types that provided the local inhabitants a greater diversity in their diet than might be expected in such a geographically limited area.

Flotation & Seeds
A technique called flotation was used to literally float and separate the organic plant remains and seeds from the excavated deposit. Seeds appear to have been an important element in the diet of the inhabitants of the shellmound. The most common and abundant seeds were found to come from grassland or moist habitats. These seeds are from species of hairgrass, the sunflower family, legume family and goosefoot. Based on when the seeds open, and could have been used, these findings suggest that the inhabitants of the shellmound lived there year round. During the early spring a variety of greens could have been collected. In late spring grass, goosefoot and red maid seeds were used. In the summer hazelnuts, hairgrass, tarweed, and sunflower would have been available. In the fall the primary resource that could be collected would have been acorns. The seeds and acorns could be stored for use during the winter months. Corms (underground stems) would have been harvested in late winter / early spring. Many of the plant species represented may have had medicinal and other uses, as well as dietary use.

It is interesting to note that the analysis of plant remains suggests acorns may have been less important in the diet of the Emeryville Shellmound residents than at many other sites in the San Francisco Bay region. This may suggest that other seeds were more available at this site or simply that resources other than acorns were more useful to the Emeryville people. A question of interest would be the relative importance in the diet of the plant versus animal foods.

Animal Bones Analysis
The results of the faunal (animal bone) analysis also provide insights into the diet of the prehistoric inhabitants of the shellmound, and the surrounding environment at the time of the site's occupation.

Three teams of zooarchaeologists worked with the animal bones from the 1999 archaeological collection. After the collection was divided by class, into mammals, fish, birds, and amphibians and reptiles, specialists in each class identified the species and genus of as many of the bones as possible. From the 1999 collection, over 82,000 mammal bones were examined and 21,000 identified to order, family, genus or species. In the bird class, some 11,000 bones, representing 41 taxa, were identified. Fish bone was of particular interest because the assemblage provides an abundance of data not previously available. Fish bone generally is small, and often was overlooked in early excavations. In 1999, many soil samples were passed through 1/16-inch screen. The result was that this excavation recovered large quantities of the small bones not collected by previous excavators at the site, who had used larger mesh screens or no screens at all. Over 79,000 fish bones were examined. 58,000 were identified at least to taxonomic order. These bones provided evidence of small fish such as sardines and anchovies, which had not been documented previously at the site, as well as a wide range of larger fish.

Fauna Collection
The fauna collection provided a wealth of data on the diet and hunting practices of the Emeryville people. In particular, this collection testifies to the wide variety of habitats that were utilized and the variety of hunting techniques that must have been practiced. In addition to the land mammals common in sites in California (deer, elk, and in lesser number coyote, rabbit, raccoon, bears, mountain lion, bobcat, antelope and smaller game) the Emeryville people captured large numbers of sea otters, as well as seals, and sea lions. Whale bone also occurs with some frequency in the deposit. Because the tule canoes known to have been used in the Bay Area ethnographically (in Spanish times) appear unlikely to have been adequate for whale hunting, it is unclear how whales were obtained. Possibly they simply beached or washed ashore in the shallow waters of the Emeryville shore. However, perhaps the Emeryville people had hunting techniques that we have not yet recognized. It is clear that they made good use of the many water resources of the Bay.

Sea Animals
In addition to sea mammals, which probably were speared on shore or in the bay, the Emeryville people also captured sturgeon up to seven feet in length, and a plethora of other fish. Bat rays comprised an important part of the fish diet. Over a third of the identified fish bone specimens represent bat rays, which could have been caught in the shallow waters off shore of Emeryville. With wind widths of over five feet and female weights averaging 25 pounds, a bat ray individual can provide a considerable quantity of excellent human food. Bat rays may have been trapped in the shallow tidal waters off the Emeryville shore by means of staked fish weirs. These are low damns of brush or reeds built in shallow water. Fish enter the shallows during high tide. As the tide recedes, fish are trapped inland of the weir, where they can be extracted by wading fisherman.

Hunting & Animal Populations
Several lines of evidence suggest that the efficient hunting of the Emeryville people and other local groups at times may have depressed local animal populations. For instance, the presence of cormorants - an important sea bird at Emeryville - appears to peak and decline in the bird bone assemblage. It has been suggested that seasonal hunting in cormorant aviaries could have disturbed breeding colonies and reduced the numbers of young sufficiently that the population had a difficult time recovering. Cormorant aviaries probably were present on Yerba Buena Island and other islands on the bay, as well as at rocky points along the bay, such as Fleming Point in Albany. Similarly, the count of sea otter bone in the Emeryville assemblage appears to peak and decline, which may suggest that otter populations were affected by Emeryville hunting practice. A major decline in sea otters - almost to the point of extinction -- occurred in the mid-1800s, when Russian and Aleuts hunted otters in the bay for their valuable furs. It is presumed that otters were eaten in Emeryville, but their furs also may have been a trade item that would be valuable in obtaining resources that were not available locally, such as obsidian.

Animals No Longer Present
The fauna assemblage at Emeryville provided glimpses of a rich habitat that today has nearly vanished around most of the bay. Animals found archaeologically at Emeryville but no longer present in the Bay Region include, elk, antelope, grizzly and black bear. Sea otters, rare today, are abundant archaeologically. Amphibians and reptile found archaeologically, which today are absent in the area and threatened in the region, include Alameda whipsnake, Western pond turtle and red-legged frog. Among birds represented in the midden at the Emeryville Shellmound are California condor, today virtually extinct, and bald eagle, now rarely seen in Central California.

The research value of the plant and animal data recovered from the Emeryville Shellmound in 1999 has only been scratched. These data will be of significant value for future researchers into the prehistoric environment, hunting and butchering practices, diet, and prehistoric ecology.