One of the most vexing problems in archaeology is explaining the shift from societies that made their living by hunting and gathering to those that made their living by growing crops. In the April issue of the journal American Antiquity, Tristram Kidder, an archaeologist with Washington University in St. Louis, has identified a correlation between climate change and the shift to farming. In eastern North America, the change from the hunting and gathering cultures of the Archaic period to the farming cultures of the Woodland period took place from about 1000 to 500 B.C. This coincided with a period of rapid global climate change that included lower temperatures, more rain and increased flooding. The greater frequency and severity of floods resulted in significant changes in the landscape, the forced abandonment of large parts of the region and, according to Kidder, a widespread and rapid "cultural transformation" that included the shift from hunting and gathering to farming.