Department of Archeology, University of Victoria, Victoria, BC V8P 5C2, CANADA.
This research traces the emergence of wild plant food production during the Late Prehistoric Period (4500 to 200 BP) on the Canadian Plateau. It builds upon ecological-evolutionary perspectives offered by theories of people-plant interactions and models of plant food production. From this, it derives a general model of wild plant food production outlining the components of such systems, the conditions favouring their development, and the consequences and correlates of these activities. This general model is expanded and made specific to the Canadian Plateau through ethnographic, ethnobotanical, ecological and archaeological evidence for root resource use by the Secwepemc (Shuswap) and other Interior Salish peoples. The implications of these findings for reconstructions of Late Prehistoric culture change are discussed.
The study has two components. It begins by demonstrating that historically, the Interior Salish peoples were not plant collectors, "adapting to" the environment, but plant food producers who "domesticated" the landscapes of the region. Ethnobotanical evidence indicates the Secwepemc managed, processed and stored a variety of plant resources to increase their productivity and availability. These actions ensured surpluses for overwintering, reducing the threat of recurrent seasonal resource stress.
Root foods were particularly important. At least 20 species were regularly harvested and stored. Practices associated with harvesting were essentially horticultural and acted at the species, population and landscape levels to increase the density and distribution of targeted species. The productivity of root resources was also increased through processing in earth ovens. An experimental reconstruction of an Interior Salish earth oven found pitcooking increased the energy value of balsamroot (Balsamorhiza sagittata), a former root staple, by 250 percent. Balsamroot contains inulin, a complex carbohydrate indigestible in its raw form.
The second component of this study traces the beginnings of these wild plant food production systems through the archaeology of earth ovens. The discussion begins with Komkanetkwa, a traditional root gathering ground of the Secwepemc located near Kamloops, British Columbia, where investigations identified the remains of 170 earth ovens, 11 of which were excavated. Similar data from four additional root processing locales, including the Upper Hat Creek Valley, Oregon Jack Creek and Potato Mountain on the Canadian Plateau and the Calispell Valley on the Columbia Plateau, are also presented.
Analysis of site types and distributions, the structure and content of earth ovens and radiocarbon age estimates associated with them reveals root food production began approximately 3100 years ago on the Canadian Plateau. The broad pattern of root resource use, consistent with ethnographic expectations, is well-developed after 2500 BP and persists until historic times. Radiocarbon age estimates (n=30) indicate a peak in activity developing between 2250 and 1750 BP.
A review of the paleoenvironmental and culture-historical context identified the conditions, consequences and correlates of these processes. The catalyst for the development of these strategies was a dramatic decline in temperatures approximately 3900 years ago. This ushered in a 2000 year period recognized as the coldest and wettest stage of the Holocene, one characterized by long, cold winters. Under these conditions, wild plant food production represents a risk reduction strategy developed by peoples of the Canadian Plateau to cope with the uncertainty' of seasonal and annual environmental variation and prolonged periods of resource scarcity.
In sum, earth ovens are the archaeological manifestations or fundamental shift in the processes of people-plant Interactions - the transition from foraging to wild plant food production which occurred on the Canadian Plateau at least 3100 years ago. This transition represents the adoption of strategies designed to ensure the productivity and availability of plant resources, particularly storable carbohydrates derived from roots. for overwintering.