Protein Residues

Recently developed techniques for distinguishing the residues from plant and animal proteins offer the possibility of identifying the uses to which prehistoric artifacts and features were put. The standard technique is crossover immunological electrophoresis (CIEP) analysis, which is typically able to match blood and other residues to modern samples at the family taxonomic level.

CIEP analysis has been most extensively applied to flaked lithic tools at a variety of sites in San Diego County. Below is a selection of studies that have obtained positive results:

  • Margaret E. Newman (1991) reported deer and rabbit residues on three artifacts from SDI-4935B, a portion of the C. W. Harris Site in west-central San Diego County.
  • Newman (1992) analyzed residues on projectile points from Indian Hill Rockshelter (SDI-2537) on the southeastern margin of the county. Positive results were obtained for pronghorn (on two Elko Eared points), deer (on a Desert Side-notched and a Dos Cabezas Serrated point), sheep (on an Elko Eared and a Cottonwood Tirangular point), and rabbit (on a Cottonwood Triangular point).
  • At sites SDI-186 and SDI-4757 in the Sweetwater River valley, Newman (1993a) reported positive results for human residues (on a scraper), bear (on two scrapers), deer (on a hammer stone and two scrapers), pronghorn (on a projectile point and a biface), rabbit (on a projectile point, a hammer stone, and two scrapers), rat/mouse (on a chopper), and trout (on a projectile point).
  • Newman (1993b) found protein residues from deer on a projectile point preform, from pronghorn on an abraded core, and from mouse on a core/hammer stone from SDI-12,809 in the Otay River valley.
  • Kathryn Puseman and Jaime Dexter (2008) identified deer residue on a fluted obsidian projectile point from SDI-2506 in Lost Valley.

The technique has also been applied to ground stone tools and milling features:

  • Robert M. Yohe, Newman, and Joan S. Schneider (1991) identified rat and mouse residues on two manos at SDI-10,246 in southwestern San Diego County.
  • Newman (1993a) found rabbit residue on a mano at SDI-186 in the Sweetwater River valley.
  • A mano and a metate from SDI-10,637 at Torrey Pines on the San Diego coast returned positive results for residues from grass and from grass and deer, respectively (Scott Cummings et al. 1996; Mealey 2009).
  • Schneider and Bonnie Bruce (2009) explored the feasibility of using the method on bedrock processing features at three sites in eastern San Diego County (SDI-813, SDI-2524, and SDI-9538). Positive results were obtained in 17 percent of the tests. Taxa identified at the features included cat (e.g., bobcat, mountain lion), dog (e.g., dog, coyote), sheep (e.g., bighorn), rabbit (e.g., rabbit, jackrabbit), rat (rat or mouse), chicken (e.g., quail), mesquite (e.g., mesquite, palo verde), and Capparidaceae (e.g., bladderpod).
  • Carmen Zepeda-Herman (2014) found protein residue evidence for acorn processing on a bedrock milling slick at SDI-19,241 near Tecate.

In other regions, CIEP analysis has been applied to non-lithic remains, including human coprolites and site soils (Newman et al. 1993).

Skepticism has been expressed concerning the reliability of protein residue analyses (e.g., Fiedel 1996).

PROSPECTS

Challenges remain in identifying the specific circumstances under which the preservation of residues is likely to have occurred, in developing more effective means of recovering residues from archaeological artifacts and features, in extending the taxonomic range and specificity that can be distinguished using CIEP, and in more effectively screening out false positive test results.