The simplest method of cooking, and doubtless that first employed, is by holding the food over, or actually placing it on, the fire, or in hot embers. Vegetable food does not as a rule allow of this process, because of the readiness with which it burns, but some kinds, e.g. roots and large seeds, may be roasted in hot embers, and existing pre-cibiculturists sometimes resort to this method.
The first great advance in the art of cookery was the invention of the underground oven, by means of which food, especially the vegetable varieties, can be cooked much more efficiently than by the primitive methods just described. Oven-cookery was probably suggested by the custom, still occasionally practised, of kindling a fire over the food to be cooked. It was but a step from this to digging a hole in the ground, into which to put the food, and, then making a fire over or around it. The next step, we may assume, was to heat the walls of the hole by means of a fire and, having raked out some of the ashes, to place the article to be cooked inside and then cover it up in order to retain the heat. Finally, we arrive at the most advanced phase of underground oven-cookery, i.e. by means of heated stones. These and the food are placed in alternate layers within the oven, forming a pile above the level of the ground, the whole being covered with matting, leaves, grass, or the like. This method may be described as "stone-baking." Generally, however, the oven is lined with, and perhaps also the layers of food and stones are separated by, some vegetable substance, so as to generate steam, which then becomes the active agent in the cooking, a method which may be described as "stone-steaming," and a very admirable one it is. Without metals or pottery which among us could devise a better?
The next great development in the art came when man discovered how to boil water. In some parts of the world, e.g. in the neighbourhood of the once famous terraces of New Zealand, nature has provided boiling pools which afford a ready means of cooking food, and the Maoris do in fact use them for this purpose. The food is placed in a basket or netting, which is lowered into the water by means of a string made fast to some fixed object, and there left until it is cooked. It was not, however, until a comparatively recent period, probably not until long after he began to employ underground ovens, that man taught himself to boil water wherever he might be. That the method of boiling food post-dated that of baking or steaming it in ovens is shown by the fact that certain pre-cibiculturists have not yet attained to it. Such is the case with the Australian aborigines, and their ignorance of the device seems to show that it was not thought of until late in the cookery period. The Fuegians and Bushmen are also said to be unacquainted with it.
The great obstacle to the boiling of water which presented itself to primitive man lay in the fact that he possessed no vessel capable of resisting the action of fire. Pottery, it should be remembered, is of quite recent introduction : it is unknown to present-day pre-cibiculturists and belongs, in fact, to the cibicultural period. With the exception of shells, the only fireproof vessels in pre-pottery days were those made of hewn stone, but the making of such vessels entails great labour, and they do not appear ever to have been widely employed for cookery of any kind. How, then, did man first boil water? Before answering this question let us first consider what vessels he employed for holding water. The most primitive were those fashioned by nature, such as segments of gourd-rind, the shells of shell-fish and eggs (e.g. those of the ostrich), the bamboo cane, and even the human skull. At a later stage he learnt to make vessels of skins and closely plaited rushes. It is obvious that none of these can be used as saucepans, though the Botocudos are said to have boiled water in bamboo vessels held over the fire. A watertight vessel which does not admit of being placed over a fire may, however, be used for heating water by filling it with water and then dropping in heated stones. This ingenious method - no doubt the earliest - was widely practised among primitive peoples and is still employed by some of the pre-cibiculturists, such as the Californians, the Esquimaux, and the Andamanese. It was in use also in isolated parts of Europe until within comparatively recent times. In Ireland hot stones were used for warming milk in the seventeenth century, and in Finland in the making of beer as late as the eighteenth century. In the earliest times the vessels most frequently employed for stone-boiling by the Californians, the Fuegians, the Kaffirs, and the native Australians were made of closely plaited rushes.