With few exceptions, fragments of thermally altered and fire-cracked stones can be found littered upon ancient landforms throughout the world. With deep origins in prehistoric hunter-gatherer societies, these fist-sized and larger stones almost always mark the location of past cooking activities. As agriculture and new technologies such as pottery came upon the scene, the frequency and utility of cooking with heated stones is seen by many to have diminished, thus marking a departure from hunter-gatherer or 'Archaic' life ways. Here, 289 radiocarbon assays from 135 separate cook-stone (Thoms 2003) features recorded in the basin-and-range region of the semi-arid lowlands of the Chihuahuan Desert (Figure 1) of the American Southwest indicate a steady use of cook-stone beginning around 4500 BP with a sharp increase in feature size and frequency around 1250/1300 BP (Figure 2). This sharp increase coincided with the appearance of the first settled villages (Reference WhalenWhalen 1994) and evidence of cultivated crops such as maize, beans, and squash in the region. The continuation of this hunter-gatherer cooking technology well into the transition of agricultural-based economies (Reference HardHard et al. 1996) reveals the inherit utility of the technology and the continued importance of wild food resources in this marginal agricultural region.
Figure 1.
Figure 2.
Cook-stone features are a common occurrence in the arid regions of the American Southwest and often the preferred means for rendering carbohydrate-rich foods such as agave, sotol and cholla buds eatable. Cook-stones retain heat from fast burning wood charcoal and, once arranged in the bottom of hand-dug pits called earth ovens, can cook plant tissue over long periods of time (20 to 60 hours). This thermal pit-processing renders the plant tissue less toxic and more nutritious.
Figure 1 shows a steady occurrence of smaller cook-stone features being generated until 1250/1300 BP. Many of these features, which usually only contained a few kilograms of cook-stone, where located out in the desert floor, well away from the alluvial fans along the mountains that would later be preferred settlement locations for agriculturalist. The small amount of cook-stone recovered from these earlier features would be inadequate heating elements for cooking many of the plants in the area. There exact function, other than possibly extending the use life of fast burning wood charcoal to cook animal tissue or parch seeds, remains unknown.
As the 1250/1300 BP 'transition' to the appearance of the first settled villages and cultivated crops approached, the size of the cook-stone heating elements increased, suggesting a changing role for cook-stone and the possibility for larger packages of processed food. The increased size of the heating elements are consistent with those noted for historic Southwestern groups who pit-baked agave and sotol in earth ovens lined with cook-stone (Reference CastetterCastetter & Bell 1938). The majority of these larger ovens are located on the alluvial fans in close proximity to the village settlements.
These data demonstrate the important role of cook-stone technology in the transition from foraging-based economies to those more reliant on cultigens. While cultivated crops were finding there way into the more arid regions of the Southwest, the development and persistence of a broad-spectrum diet is clearly evidenced by the presence of cook-stone facilities in the region. The presence and increased utilisation of cook-stone technology during periods of increasing agricultural dependence may best be viewed as a 'buffering strategy' during periods of low crop productivity or even failure (Reference LeachLeach & Bradfute 2004).
