The shift from llama pastoralism to potato agriculture in the Jauja-Huancayo basin of highland Peru has previously been considered a result of the Wari conquest. An alternative hypothesis, based on population pressure, is suggested here. As an adjunct to the description of population distribution, the concepts of an exploitable territory threshold model and of site catchment as a part of central place theory are explored.

In an earlier article, we presented a model for the culture history of the Columbia Plateau. In response to comment about this model, we have clarified our definition of the emergence of Plateau culture and have elaborated on the appearance of both blade and microblade industries in the area.

Excavations of the last decade have yielded much data which cannot be adequately handled by extant models of Plateau cultural development. The 15,000 years of pre-history revealed by these new data appear to break into seven distinct periods. For each cultural period we present a synthesis of elements, including varying trait-unit intrusions from both the Great Basin and the Canadian Plateau. Included in this examination are such important new factors as a pre-Old Cordilleran stemmed point tradition and a microblade tradition some 5,000 years in duration. Reanalysis also suggests that the "emergence" of Columbia Plateau culture (as ethnographically known) can be placed at about the time of Christ, instead of about A.D. 1200-1300 as previously hypothesized.