The history of cooking vessels before the development of pottery is minimal due to the limited archaeological evidence. It has been possible to extrapolate likely developments based on methods used by latter peoples. Among the first of the techniques believed to be used by stone age civilizations were improvements to basic roasting. In addition to exposing food to direct heat from either an open fire or hot embers it is possible to cover the food with clay or large leaves before roasting to preserve moisture in the cooked result. Examples of similar techniques are still in use in many modern cuisines.
Of greater difficulty was finding a method to boil water. For people without access to natural heated water sources, such as hot springs, heated stones could be placed in a water-filled vessel to raise its temperature (for example, a leaf-lined pit or the stomach from animals killed by hunters). In many locations the shells of turtles or large mollusks provided a source for waterproof cooking vessels. Bamboo tubes sealed at the end with clay provided a usable container in Asia, while the inhabitants of the Tehuacan Valley began carving large stone bowls that were permanently set into a hearth as early as 7000 BC.
According to Frank Hamilton Cushing, native American cooking baskets used by the Zuni (Zuñi) developed from mesh casings woven to stabilize gourd water vessels. He reported witnessing cooking basket use by Havasupai in 1881. Roasting baskets covered with clay would be filled with wood coals and the product to be roasted. When the thus hardened clay separated from the basket, it would become a usable clay roasting pan in itself. This indicates a steady progression from use of woven gourd casings to waterproof cooking baskets to pottery. Other than in many other cultures, native Americans used and still use the heat source inside the cookware. Cooking baskets are filled with hot stones and roasting pans with wood coals. Native Americans, both in the East and in the West, would form a basket from large leaves to boil water, according to historian and novelist Louis L'Amour. As long as the flames did not reach above the level of water in the basket, the leaves would not burn through.
The development of pottery allowed for the creation of fireproof cooking vessels in a variety of shapes and sizes. Coating the earthenware with some type of plant gum, and later ceramic glazes, converted the porous container into a waterproof vessel. The earthenware cookware could then be suspended over a fire through use of a tripod or other apparatus, or even be placed directly into a low fire or coal bed as in the case of thepipkin. Ceramics (including stoneware and glass) conduct poorly, however, so ceramic pots must cook over relatively low heats and over long periods of time (most modern ceramic pots will crack if used on thestovetop, and are only intended for the oven). Even after metal pots have come into widespread use, earthenware pots are still preferred among the less well-off, globally, due to their low production cost.