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.
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.
What were the key findings of these specialists who studied
plant and animal remains at the shellmound?
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.
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.
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.
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.
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.
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.
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.
