Genetic Connections

Evidence of genetic relationships between different Native populations during the prehistoric and historic periods may shed light on prehistoric patterns of migration, as well as the degree to which different groups interacted.

Until recently, information on skeletal measurements was the main tool for addressing these issues. However, some uncertainty exists as to the extent to which specific metric traits are determined genetically, rather than during individual development.

Malcolm J. Rogers’ archaeological excavations at middle Holocene (La Jollan) coastal sites in San Diego County and northern Baja California during the 1920s and 1930 yielded skeletal material that was subsequently analyzed by Spencer L. Rogers (1963, 1977b) and Rose Noble Tyson (Noble 1973; Tyson 1980). Spencer Rogers reported that the middle Holocene population in this region differed substantially from populations on the Santa Barbara Channel Islands and the adjacent mainland, as well as in the American Southwest. He noted more similarity with populations in central California and the Great Basin, and with Japan in particular. Discussing the smaller stature of the local middle Holocene population, he argued:

“The short stature of the South Coast Californians cannot easily be explained as a result of inadequate food or the selective role of a rigorous environment….The relative short stature of these populations must probably be regarded as a feature of racial inheritance….An hypothesis in explantion of this would be that these groups were a component of a population which moved at an early time southward down the Pacific Coast to the west of the later migration trends into the Great Basin, the Southwest and Mexico….These short-statured population segments apparently became isolated from other stocks and retained their identity for several millennia before becoming drastically modified through inbreeding with other strains or meeting with extinction” (Rogers 1977b:4).

Travelers during the early historic period were in disagreement as to whether the local Diegueño people they encountered were large or small. Observers who approached from the south, including Cabrillo in 1542 (Wagner 1929) and Serra in 1769 (Serra 1995), described the native people as large or tall. However, members of the 1774 Anza party, who came from the Colorado River to the east, found the Diegueño to be either of ordinary height or small (Bolton 1930). Modern measurements on Diegueño, Luiseño, Cupeño, and Cahuilla populations have yielded mean statures that are greater than those for earlier coastal populations but slightly less than those for River Yumans (Gifford 1926; Sutton 2009).

Analysis of mitochondrial DNA (mtDNA) from both archaeological remains and modern populations now offers a prospect of making significant advances in understanding genetic relationships in the female line. However, the available sample sizes are still small, and the appropriate methods for interpreting the evidence are uncertain.

Jason A. Eschleman and David Glenn Smith (2007) reviewed mtDNA evidence reported from both prehistoric archaeological remains and modern Native Americans. One of their conclusions was that mtDNA group distributions at early archaeological sites on the southern Channel Islands were markedly similar to the distributions of modern Takic (e.g., Luiseño) distributions but markedly different from ancient and modern Chumash patterns. Another conclusion was that “modern southern California Uto-Aztecan [i.e., Takic] groups appear more closely related to nearby Yuman speakers than to other Uto-Aztecan populations in the Southwest, Great Basin, or central Mexico” (Eschleman and Smith 2007:297). This suggested an hypothesis that “Uto-Aztecan languages spread without an accompanying pronounced spread of mtDNA types” (Eschleman and Smith 2007:297), that is, that Takic-speaking individuals’ descent in the maternal line was from the coastal region’s pre-Takic inhabitants.

John R. Johnson and Joseph G. Lorenz (2006) focused on modern populations, but they used genealogical documentation to verify matrilineal links to specific pre-contact ethnic groups. In their sample, “the similarity in haplogroup distribution bewteen Yuman and Uto-Aztecan groups appears to be the result of extensive intermarriage between the Ipai and Luiseño” (Johnson and Lorenz 2006:45).

PROSPECTS

Additional analyses of such metric characteristics as stature and head shape on skeletan assemblages, particularly from the earlier periods of prehistory, may be able to contribute to understanding the origins of early New World populations. Analyses of both modern Native American and prehistoric DNA, principally mtDNA but also potentially including Y-chromosome and other forms of nuclear DNA, may clarify issues of continnuity or discontinuity in local populations through time, genetic homogeneity or heterogeneity within the region, and wider prehistoric interregional connections.