The Evolution of Treponemal Disease in the Santa Barbara Channel Area of Southern California Phillip L .Walker, Patricia M . Lambert, Michael Schultz, and Jon M . Erlandson Introduction Studies of human skeletal remains from the Santa Barbara Channel area of south- ern California provide a unique perspective on the evolution of treponematosis in the New World . The Indians of this area buried their dead in cemeteries through- out much of the Prehistoric period . As a result, there are many large, well-docu- mented skeletal collections from the Santa Barbara Channel area that record changing disease patterns over many millennia . These collections provide some of the earliest evidence for treponemal infections in the Western Hemisphere. They also shed light on the possibility that European colonists introduced new forms of treponemal disease to Native Americans. At the time of European contact, the Chumash Indians of the Santa Barbara Channel area had a nonagricultural economy based on intensive fishing and wild-seed crop exploitation . This adaptation allowed them to maintain a coastal population whose density and level of political complexity at SBa-52 rivaled that of many North American agriculturalists (Gamble, Walker, and Russell 2001; Lambert and Walker 1991 ; Walker and Hudson, 1993) . Their large villages and extensive trade networks appear to have created conditions conducive for the maintenance and spread of an endemic form of treponemal disease. We know that people have lived in the Santa Barbara Channel area for at least 12,000 years (Erlandson 1994, 1997 ; Erlandson and Cotten 1991 ; Erlandson et al . 1996 ; Johnson et al . 2000 ; Kennett 1998 ; table 11 .1) . Archaeological data show that before the epidemic-induced collapse of the Chumash population dur- ing the Historic period (Walker and Johnson 1992, 1994), there were long-term trends toward population growth and increased sedentism . These Prehistoric demographic trends are suggested by increases in the number and size of dated cemeteries and habitation sites (Breschini, Haversat, and Erlandson l996 ; I am-