Fire is important for warmth, protection, cooking, light, pest control, tool-making, social interaction and perhaps hunting. There are some early Stone Age sites in Africa, that can may seen as candidates for the documentation of early controlled fire use of our ancestors, but actually only the site of Gesher Benot Ya’aqov (GBY) in Israel seems to offer unequivocal evidence of anthropogenic fire use across the Acheulian world.
Large areas of Africa’s savanna today maintain a balance of tree and grass cover only through the disturbances caused by natural and human use of fire and extensive browsing by animals. These “unstable” savannas extend across the Sahel and from southern Kenya across the broad Zambezi woodland zone into southern Africa. The antiquity of fire- and browse-maintained savanna is uncertain, but evidence of fire in the African record pre-dates the Quaternary.
Naturally occurring bush fires are generated by lightning strikes that accompany the onset of seasonal monsoons, and in the late dry season, the landscape offers fuel in the form of grass and wood to support such fires. Early hominids would certainly have recognized the effects of fire on the landscape, and possibly on plant and animal foods. Transforming that recognition into deliberate control or making of fire requires some understanding of the physical processes linked with burning as well as a technique of fire- maintenance.
Archaeological evidence for the controlled use of fire during the African Acheulian remains often equivocal, with uncertainty existing about the anthropogenic origin of traces of burning and the role of taphonomic processes in creating associations between artifacts and burnt areas.
The most prominent examples of an association of oxidized sediment with artifacts have been described from Koobi Fora and Chesowanja (Kenya) and are dated between 1,6-1,4 Mya BP.
FxJj 20 Main (Koobi Fora) contains the “Karari industry” along with fauna and discrete concentrations of fully oxidized sediment near the base of the sequences. The oxidized deposits are of a circular form, which could have represented a hearth. The areas of burning seem to have been revisited, perhaps as part of the site’s seasonal use. Nearby at FxJj 20 East, phytoliths recovered from several burnt areas show that hominids could have used a variety of woods to make fires, including easily ignited palm wood. A similar association of oxidized sediments with artifacts occurred at Chesowanja, near the Lake Baringo at site GnJj 1/6E with “Developed” Oldowan artifacts.
A hearth-like depression was excavated at Olorgesailie, Kenya. Some microscopic Charcoal was found, but it could have resulted from a natural brush fire. In Gadeb, Ethiopia, fragments of welled tuff that appeared to have been burned were found in Locality 8E, but re-firing of the rocks may have occurred due to local volcanic activity. In the Middle Awash River Valley, cone-shaped depressions of reddish clay were found that could have been created by temperatures of 200° C. These features are thought to be burned tree stumps.
The interpretation of traces of fire in the South African caves and breccias is less affected by bush fires, but certainly compromised by taphonomic issues. In Member 3 at Swartkrans, 270 bone fragments from an assemblage of more than 100000 specimens have been identified as affected by heat, with 47% of the burnt bone subjected to temperatures approaching or above 600° C The burnt bone occurs throughout much of the six meters of the Member 3 deposit, which makes it a little less likely that it is intrusive. The Member 3 burning could be the result of repeated use of fire by hominids, perhaps for cooking meat based on the more frequent association of cutmarks on the burnt than the unburnt bone. There are also claims about controlled fire-making by about1.7 Million years ago at Wonderwerk Cave. Anyhow, no clearly defined hearths have been identified and no data on the spatial distribution of burnt artifacts and bone are available.
Future excavations and interpretations about human fire-use during the Acheulian will have to compete against the meticulous work of Goren-Inbar at the Gesher Benot Ya’aqov (GBY)-site. Dated to approximately 780 k.a., GBY contains the most compelling evidence for the early use of fire in the form of multiple clusters of burnt flint. Goren-Inbar proposes, since hearths serve as focal points for activities, that they display areas of accumulation of small refuse. If clusters of small burned debris can be traced by excavation, they can serve as indicators of hearths. These hearths are designated as “phantom hearths”, because they represent “structures latentes” (sensu Leroi Gourhan) that lack other observable traits like structuring, discoloration of sediments, ash and charcoal. “Phantom hearths” at GBY were defined by highlighting significant accumulations of burned microdebitage within the deposits exceeding the “expected” level of burned and unburned debris, which was defined by the complete archaeological record and by the application of robust statistical methods. Fifteen layers in total all displayed evidence of burning. A total of three of these layers showed evidence of controlled burning.
Can we assume that fire use at GBY indicates a technique those components could be socially transmitted from the hominids at GBY to other people who entered and settled in Europe and Asia? The answer is probably: No. In Europe we have no secure evidence for anthropogenic fire before 400 k.a. BP. After this date, fire evidence has been detected in several Middle Pleistocene sites like Terra Amata, Grotte du Lazaret, Bilzingsleben, Schöningen and Beeches Pit.
It is suggested, that improved methods of excavation and data processing will identify more latent structures like combustion areas, hearths and clusters of human activity in very early archaeological sites, providing a more unequivocal evidence for a differentiated behaviour like the use of fire by early humans in the future.
A first step into this direction is the work of Berna et al., who demonstrated that micromorphology and and microspectroscopy may provide evidence of fire, in the form of burned bone and ashed plant remains, even without the macroscopic presence of combustion areas. Data about intact sediments at Wonderwerk, probed with these techniques, gave secure evidence that burning took place in the cave during the early Acheulean occupation, approximately 1.0 Ma. ago. Anyhow it can not be proven, that it was enflammed by human activity.