Many cultures have a recognizable cuisine, a specific set of cooking traditions using various spices or a combination of flavors unique to that culture, which evolves over time. Other differences include preferences (hot or cold, spicy, etc.) and practices, the study of which is known as gastronomy. Many cultures have diversified their foods by means of preparation, cooking methods, and manufacturing. This also includes a complex food trade which helps the cultures to economically survive by way of food, not just by consumption.
Ovens are mostly hollow devices that get very hot (up to 500 °F (260 °C)) and are used for baking or roasting and offer a dry-heat cooking method. Different cuisines will use different types of ovens. For example, Indian culture uses a tandoor oven, which is a cylindrical clay oven which operates at a single high temperature. Western kitchens use variable temperature convection ovens, conventional ovens, toaster ovens, or non-radiant heat ovens like the microwave oven. Classic Italian cuisine includes the use of a brick oven containing burning wood. Ovens may be wood-fired, coal-fired, gas, electric, or oil-fired.
The earliest use of the term in the post-industrial age appears to be in 1946 in The Farmer, a quarterly magazine published and edited from his farm by F. Newman Turner, a writer and pioneering organic farmer. The magazine sponsored the establishment of the Producer Consumer Whole Food Society Ltd, with Newman Turner as president and Derek Randal as vice-president. Whole food was defined as "mature produce of field, orchard, or garden without subtraction, addition, or alteration grown from seed without chemical dressing, in fertile soil manured solely with animal and vegetable wastes, and composts therefrom, and ground, raw rock and without chemical manures, sprays, or insecticides," having intent to connect suppliers and the growing public demand for such food. Such diets are rich in whole and unrefined foods, like whole grains, dark green and yellow/orange-fleshed vegetables and fruits, legumes, nuts and seeds.
Phylogenetic analysis suggests that human ancestors may have invented cooking as far back as 1.8 million to 2.3 million years ago. Re-analysis of burnt bone fragments and plant ashes from the Wonderwerk Cave, South Africa, has provided evidence supporting control of fire by early humans there by 1 million years ago. There is evidence that Homo erectus was cooking their food as early as 500,000 years ago. Evidence for the controlled use of fire by Homo erectus beginning some 400,000 years ago has wide scholarly support. Archaeological evidence from 300,000 years ago, in the form of ancient hearths, earth ovens, burnt animal bones, and flint, are found across Europe and the Middle East. Anthropologists think that widespread cooking fires began about 250,000 years ago, when hearths started appearing.
Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. Corn (maize), wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide. Most of the grain that is produced worldwide is fed to livestock.