The colonization of Beringia appears closely linked to the arrival of the oldest firmly documented archeological tradition in mid-latitude North America (Paleoindian). The discovery of a Paleoindian complex in central Alaska, combined with the recent redating of the Bering Land Bridge and key archeological sites, suggests that Beringia was settled during the final Pleistocene interstadial (12,000 to 11,000 years before present). Its population expanded rapidly into other parts of the New World. Beringia probably was colonized in response to changes in climate and vegetation that occurred during this interstadial. Access to the Americas was controlled by Beringian environments and not by changing sea levels or continental ice masses.

Ongoing research in the Nenana Valley is uncovering a complex record of Late Glacial settlement in the foothills of the Alaska Range. A local eolian sequence provides relatively precise stratigraphic and chronological control, permitting integration with regional paleoclimatic history. Initial occupation seems to have occurred approximately 12,000 years ago, and is represented by several assemblages containing bifacial points. Microblade technology did not appear until ca. 10,500 B.P. The valley probably was exploited on a seasonal basis for large mammal procurement.

This paper explores the relation between the geographic shifts in prehistoric hunting populations and changes in climate between 4500 and 3000 before present (BP) within the polar regions from the Yenisei River in Siberia to Greenland. We have chosen this time period because major human geographic changes occurred over much of northeastern Asia and northern North America, and because these changes appear to be linked, at least in part, to a palaeoclimatic fluctuations. The cultures under consideration have been termed the Early and Middle Neolithic (Syalakh and Bel’kachi) in Siberia and the Arctic Small Tool Tradition (with such local variants as Denbigh, Independence I, Pre-Dorset, and Sarqaq) in North America. Despite these terminological differences, these groups shared such a close similarity in their technology and adaptive patterns that they must have once shared a direct historical relation.

Substantial conflict exists over water management and allocation in the Platte River Basin of Nebraska. An interdisciplinary computer simulation model, representing the water quantity, water quality, environmental, and economic dimensions of the conflict, was developed in order to analyze the tradeoffs among allocation scenarios. Most importantly, decisionmakers and interest groups were involved in model development. Simulation results for a base case and two scenarios are presented. One scenario favors protection of instream flow for wildlife; the other favors water diversions for agriculture. Impacts of the instream flow scenario, as measured by the amount of land irrigated, groundwater levels, the amount of wildlife habitat for cranes and catfish, and net agricultural benefits did not differ greatly from those of the base case. However, impacts of the diversion scenario were substantial. On the negative side, instream flows and wildlife habitat declined an average of 39 percent; while, on the positive side, groundwater levels and net agricultural benefits each increased 6 percent. The modeling process was successful insofar as it promoted an understanding among the highly diverse interest groups of the systems nature of the Basin. One agreement on a water diversion schedule among three of the parties has been reached, partly as a result of this process. More comprehensive compromises have not yet been forged. Our experience, however, indicates that modeling success at the policymaking level depends more on the extent to which the policymakers understand the model than it does on model sophistication.

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