The Desert's Past: A Natural Prehistory of the Great Basin. By DONALD K. GRAYSON. (Washington, D.C.: Smithsonian Institution Press, 1993. xx + 356 p p . $44.95.) Fragmentary clues to the Great Basin's environmental history reveal a past very different from the Great Basin of m o d e r n times. In this elegant book Donald Grayson gathers together many of these clues to build a "natural prehistory," a p a n o r a m i c acc o u n t of the last 25,000 years in the Great Basin, its landscapes, a n d the plants, animals, a n d people who lived there. T h e a u t h o r begins with the first public recognition, by J o h n C. Fremont, of a "Great interior Basin" in N o r t h America where rivers a n d lakes find n o outlet to any ocean. This hydrographic definition of the Great Basin is but o n e of several ways scientists distinguish the region: it is also distinctive in physiography (the Basin a n d Range geologic province), botany (the shrublands a n d woodlands of the cold Great Basin desert), a n d anthropology (the h o m e l a n d of Ute, Paiute, Shoshoni, a n d Washo peoples). How did it get to be this way? T h e answer is by n o means obvious. Were the r e a d e r somehow transported to the Great Basin of 20,000 years a g o — a world of lakes a n d glaciers, forests a n d elephants—the Great Basin of today probably would be considered an unlikely future. For o n e thing, n o o t h e r h u m a n s would be surveying the scene. T h e r e a d e r would, however,
share the landscape with some two dozen g e n e r a of mammals a n d birds that are now extinct. Grayson gives an excellent b a c k g r o u n d o n the first peopling of the Americas at the close of the Pleistocene and o n the mammalian bestiary lost to N o r t h America at that same time; t h e n h e examines how these animals m e t their fates. Grayson has played a p r o m i n e n t role in the debate over the causes of these extinctions, m o u n t i n g forceful arguments against the hypothesis that the first Americans killed t h e m all off. Instead, h e suggests, massive climate c h a n g e resulted in greater aridity, reorganization of biotic communities, a n d the sweeping extinctions. Increased aridity is best seen in the histories of glaciers a n d great Pleistocene lake systems in the Great Basin (chapter 5). T h e degree of biotic reorganization that occurred is best visualized by considering late Pleistocene plant communities (chapter 6) a n d animal populations (chapter 7). C o m p a r e this Pleistocene setting with the last 10,000 years, the H o l o c e n e (chapter 8): the e n v i r o n m e n t got drier a n d warmer (10,000-7,500 years ago), t h e n drier a n d warmer still (7,500-4,500 years ago), then slightly cooler a n d wetter (4,500 years ago to now). Lakes shrank, marshes dwindled, rivers c h a n g e d course. Ranges