John R. Johnson, Ph.D.
Curator of Anthropology, Santa Barbara Museum of Natural History
The presence of a small clam in Indian middens is providing the first archaeological clues to a possible environmental crisis suffered by the Chumash Indians about eight centuries ago. A major drought hit much of the American Southwest between AD 1150 and AD 1300, evidenced by lowered lake levels and narrow tree-ring growth bands. Populous pueblos in such places as Mesa Verde and Chaco Canyon were abandoned during this period. Archaeological evidence is accumulating to demonstrate that California Indians suffered as well. Some Chumash villages seem to have been abandoned or relocated during this time, and social disruption and warfare increased among the people.
Detailed study of marine sediment cores from the Santa Barbara Channel reveals a past record of sea temperatures that covers thousands of years. During the drought on the mainland that began about A.D. 1150, significant temperature changes in local ocean waters may have led to the collapse of marine resources on which the Chumash depended for their livelihood. Archaeologists have previously documented major changes in Chumash culture around this period.
For the past seven years, the Museum's anthropology staff and volunteers have been carefully sorting and analyzing archaeological samples excavated at Shuku, a former village at Rincon Point, to shed light on changes in Chumash life during the 2,000 years preceding European contact. In addition to sharks and rays, which were a major component in Chumash diet, the residents of Shuku were also very fond of shellfish species such as mussel, pismo clam, and littleneck clam. It is the presence of Donax gouldii, a small clam which reaches its northern limit in the Santa Barbara region, that has caused much excitement among archaeologists. It provides the first archaeological marker that correlates marine sediment core studies with discoveries at an archaeological site. The clam is an excellent indicator of warm water events and its abundance in certain excavated samples appears to signal the extreme warming of sea temperatures that occurred about eight centuries ago. The discovery also suggests that changing environmental conditions forced the Chumash to modify their diet in addition to relocating their villages.
[Originally published in Santa Barbara Museum of Natural History Annual Report 1995, pp. 2-3]
John R. Johnson is curator of Anthropology for the Santa Barbara Museum of Natural History. For questions or comments send e-mail to the following address: firstname.lastname@example.org