Most anthropologists believe that cooking fires first developed around 250,000 years ago. The expansion of agriculture, commerce, trade and transportation between civilizations in different regions offered cooks many new ingredients. New inventions and technologies, such as pottery for holding and boiling water, expanded cooking techniques. Some modern cooks apply advanced scientific techniques to food preparation. Culinarians are required to have knowledge of food science, nutrition and diet and are responsible for preparing meals that are as pleasing to the eye as well as to the palate. Culinary art, where "culinary" means "related to cooking", is the art of the preparation, cooking and presentation of food, usually in the form of meals. People working in this field – especially in establishments such as restaurants – are commonly called "chefs" or "cooks", although, at its most general, the terms "culinary artist" and "culinarian" are also used. Table manners ("the table arts") are sometimes referred to as a culinary art.