Answer:
The Progress of Fire Control
The human control of fire likely required the cognitive ability to conceptualize the idea of fire, which itself has been recognized in chimpanzees; great apes have been known to prefer their foods cooked. The fact that experimentation with fire occurred during the early days of humanity should come as no surprise.
Archaeologist J.A.J. Gowlett offers this general outline for the development of fire use: opportunistic use of fire from natural occurrences (lightning strikes, meteor impacts, etc); limited conservation of fires lit by natural occurrences; use of animal dung or other slow-burning substances to maintain fires in wet or cold seasons; and finally, kindled fire.
Early Evidence
The controlled use of fire was likely an invention of our ancestor Homo erectus during the Early Stone Age (or Lower Paleolithic). The earliest evidence of fire associated with humans comes from Oldowan hominid sites in the Lake Turkana region of Kenya. The site of Koobi Fora contained oxidized patches of earth to a depth of several centimeters, which some scholars interpret as evidence of fire control. The Australopithecine site of Chesowanja in central Kenya (about 1.4 million years old) also contained burned clay clasts in small areas.
Other Lower Paleolithic sites in Africa that contain possible evidence of fire include Gadeb in Ethiopia (burned rock), and Swartkrans (burned bones) and Wonderwerk Cave (burned ash and bone fragments), both in South Africa.
The earliest evidence for controlled use of fire outside of Africa is at the Lower Paleolithic site of Gesher Benot Ya'aqov in Israel, where charred wood and seeds were recovered from a site dated 790,000 years old. Other evidence has been found at Zhoukoudian, a Lower Paleolithic site in China, Beeches Pit in the U.K., and Qesem Cave in Israel.
An Ongoing Discussion
Archaeologists examined the available data for European sites and concluded that habitual use of fire wasn't part of the suite of human behaviors until about 300,000 to 400,000 years ago. They believe that the earlier sites are representative of the opportunistic use of natural fires.
Terrence Twomey published a comprehensive discussion of the early evidence for the human control of fire at 400,000 to 800,000 years ago. Twomey believes that there is no direct evidence for domestic fires between 400,000 and 700,000 years ago, but he believes that other, indirect evidence supports the notion of the controlled use of fire.
Indirect Evidence
Twomey's argument is based on several lines of indirect evidence. First, he cites the metabolic demands of relatively big-brained Middle Pleistocene hunter-gatherers and suggests that brain evolution required cooked food. Further, he argues that our distinctive sleep patterns (staying up after dark) are deeply rooted and that hominids began staying in seasonally or permanently cool places by 800,000 years ago. All of this, says Twomey, implies effective control of fire.
Gowlett and Richard Wrangham argue that another piece of indirect evidence for the early use of fire is that our ancestors Homo erectus evolved smaller mouths, teeth, and digestive systems, in striking contrast to earlier hominids. The benefits of having a smaller gut could not be realized until high-quality foods were available all year long. The adoption of cooking, which softens food and makes it easier to digest, could have led to these changes.
Hearth Fire Construction
A hearth is a deliberately constructed fireplace. The earliest examples were made by collecting stones to contain the fires, or simply by reusing the same location again and again and allowing the ash from previous fires to accumulate. Hearths from the Middle Paleolithic period (about 200,000 to 40,000 years ago) have been found at sites such as the Klasies River Caves in South Africa, Tabun Cave in Israel, and Bolomor Cave in Spain.
Earth ovens, on the other hand, are hearths with banked and sometimes domed structures built of clay. These types of hearths were first used during the Upper Paleolithic period for cooking and heating and sometimes for burning clay figurines. The Gravettian Dolni Vestonice site in the modern Czech Republic has evidence of kiln construction, although construction details did not survive. The best information on Upper Paleolithic kilns is from the Aurignacian deposits of Klisoura Cave in Greece.
Fuels
Relict wood was likely the fuel used for the earliest fires. Purposeful selection of wood came later: hardwood such as oak burns differently than softwood such as pine, since the moisture content and density of a wood all affect how hot or long it will burn.
In places where wood was not available, alternative fuels such as peat, cut turf, animal dung, animal bone, seaweed, and straw were used to build fires. Animal dung was likely not consistently used until after animal domestication led to the keeping of livestock, about 10,000 years ago.
