Introduction

Charcoal, burnt sediments, heat-affected rocks, and other signs of fire are prevalent at archaeological sites all over the world. Evidence of early fire use has been exposed to the elements for hundreds of thousands of years, affecting preservation. Consequently, researchers have focused on the absence or presence of early anthropogenic fire (Gowlett and Wrangham 2013), often within single sites. However, research on early fire use also involves methodological development, a focus on context and formation processes, and an interest in synthesizing data and patterns (e.g., Alperson-Afil and Goren-Inbar 2010; Berna et al. 2012; Goldberg and Berna 2010; Gowlett and Wrangham 2013; Roebroeks and Villa 2011; Sorensen 2017). The origin of the controlled use of fire, originating perhaps one million years ago in Africa (e.g., Berna et al. 2012; Brain and Sillen 1988), is associated with light, warmth, predator evasion, cooking, and socializing (e.g., Bentsen 2014; Clark and Harris 1985; Wrangham 2009), and fire would continue to be used for these purposes for millennia. Fire technology was crucial to survival and ultimately became an embedded part of the chaine operatoire of other technologies, such as pottery making (e.g., Doherty 2015; Gosselain 2000; Jeffra 2015). Furthermore, the ritual context of fire use is, for example, included in studies of cremation (e.g., Flohr Sørensen and Bille 2008; Oestigaard 2000; Williams 2015). Fire has, in short, been used over a large time span and in various ways all over the world. A brief overview of the origins of anthropogenic fire and important areas of use is presented here.

Early Fire Interaction

It has been suggested, based on modern primate studies, that the origins of fire use can be traced far back in evolution. For example, chimpanzees in Senegal are able to predict the development of wildfires, calculate when and how fast to move to avoid the fire, and travel and forage in burned areas (Pruetz and Herzog 2017; Pruetz and LaDuke 2010). Chimpanzees and other great apes also preferred cooked over uncooked food in studies at research stations (Wobber, Hare, and Wrangham 2008). Similar interaction with natural fires was possibly the starting point for anthropogenic fire, as early fire users may have harvested fire from wildfires (e.g., Perlès 1977).

Early fire interaction could have affected physical evolution. “The cooking hypothesis” suggests that physical developments such as a large brain and a reduced digestion system are linked to the introduction to cooked food, which is easier to digest than raw food (e.g., Wrangham 2009; Wrangham and Conklin-Brittain 2003). There is a marked difference in the teeth and gut size of Homo erectus, at 1.8 million years ago, suggesting that control of fire and cooking was prevalent in the early Pleistocene (e.g., Gowlett and Wrangham 2013; Wrangham 2009). However, the cooking hypothesis has been questioned; for example, researchers conducted experiments cutting meat with stone tools and demonstrated that processing uncooked food has similar benefits to cooking food (Zink and Lieberman 2016).

The Origins of Fire Use

Baked sediments at Kenyan sites such as Chesowanja (e.g., Gowlett et al. 1981) and FxJj20 (e.g., Bellomo 1994), with dates around 1.5 million years ago, are among the earliest archaeological indicators of fire use. The evidence is ambiguous after years of exposure to the elements, which sparked actualistic studies showing that anthropogenic fires are more likely to produce enough heat and sustain the heat long enough to leave bowl-shaped combustion features (Bellomo 1994; Bellomo and Harris 1990). Actualistic studies were also important to understand potentially burnt bones found at Swartkrans Cave, South Africa, in Member 3, dated to approximately 1–1.5 million years ago (Brain 1993; Brain and Sillen 1988). There is evidence for leopard predation on hominins at Swartkrans, and controlled use of fire could have helped to ward off predators during the Pleistocene (e.g., Brain and Sillen 1988; Thackeray 1990). Actualistic studies have become crucial parts of fire research, as important contributions have been made to the formation of combustion features, how temperatures affect sediments and artifacts, and how one may recognize burning through discoloring, for example (e.g., Mallol et al. 2013; Miller and Sievers 2012; Nicholson 1993; Stiner et al. 1995).

Micromorphological studies have produced other important perspectives on early fire use. On the one hand, signs of fire use can be revealed or further examined through microstratigraphic analyses. One example is at Wonderwerk Cave, South Africa, where the presence of ashed plants and burnt bones in samples dating to approximately one million years ago was confirmed through micromorphology (Berna et al. 2012). On the other hand, such studies also show that the identification of fire evidence is not always a straightforward process. For example, micromorphological analyses were conducted at the Chinese cave site Zhokoudian in the 1990s. Dark deposits at the site had for a long time been considered clear evidence of control of fire before four hundred thousand years ago, but the micromorphological studies implied that the dark organic-rich deposits had been washed into the site (e.g., Goldberg et al. 2001). The debate of early fire use at Zhokoudian continues as field research and analyses after 2009 have recovered burned areas, potential ash, and burned bones in contexts approximately three hundred thousand years old (Gao et al. 2017), although microstratigraphic studies of these features are not available.

Spatial studies and the combination of different perspectives are other approaches to the origins of fire use. Burnt microartifacts, seeds, and wood and their spatial distribution at the site Gesher Benot Ya’aqov in the Middle East, for example, implies extensive fire use at approximately 790,000 years ago (e.g., Alperson-Afil and Goren-Inbar 2010; Alperson-Afil, Richter, and Goren-Inbar 2007; Goren-Inbar et al. 2004). However, the inconsistent evidence of fire use before three hundred thousand to four hundred thousand years ago could imply that fire production and habitual fire use developed later than opportunistic fire use (e.g., Roebroeks and Villa 2011). Furthermore, some researchers have suggested that Neandertals did not control fire (e.g., Dibble et al. 2018; Sandgathe et al. 2011), although there is evidence for fire production (Sorensen, Claud, and Soressi 2018) and fire use for tool production (hafting) (e.g., Koller, Baumer, and Mania 2001; Kozowyk et al. 2017) at sites occupied by Neandertals.

In summary, the origins of fire use are much debated. Fire was possibly used by hominins as early as 1.5–1.8 million years ago (e.g., Gowlett and Wrangham 2013), but perhaps not habitually used before approximately three hundred thousand to four hundred thousand years ago (Roebroeks and Villa 2011). There is, however, a need for researchers to focus on the process of anthropogenic interaction with fire and not just its origin point in time and space (e.g., Chazan 2017; Gowlett and Wrangham 2013). We shall now leave the origins debate and focus on some of the uses of fire.

Fire for Heat

Fire provides heat. Several experimental studies have shown that controlled campfires generate temperatures around 300°C to 800°C (see, e.g., Bellomo and Harris 1990; Bentsen 2013; Sievers and Wadley 2008; Théry-Parisot 2002, 2001), enough to heat its surroundings and provide some relief from a cold environment. The heat from a fire can be retained in rocks, but early Palaeolithic hearths are not contained by stone linings (Bentsen 2014; Chazan 2017). Indeed, stone-lined hearths seem to appear only from the Upper Palaeolithic (e.g., Chazan 2017 and references therein).

Fire-cracked rocks appear in large quantities in the archaeological record at approximately thirty thousand to fifty thousand years ago (e.g., Speth 2015; Thoms 2008), implying that the heat-retaining properties of rocks were familiar at that time. Fire-cracked (also called thermally altered or heat-affected) rocks generally change color, break, and develop factures as a result of exposure to heat during various processes (e.g., Backhouse and Johnson 2007; Bentsen and Wurz 2017; Brink and Dawe 2003; Graesch et al. 2014; Petraglia 2002). Rocks as heating elements are known from some ethnographic and archaeological contexts. One example is the populations inhabiting the Arctic region between 2500 bce and 1500 ce. Various types of heating structures are known from these populations, including stone-lined fires, box hearths with a layering of flat stones in the center of the feature, and hot-rock features for heating the room (e.g., Berglund 2003; Odgaard 2003; Olsen 1998). Another well-known example of rocks used as heating elements is the “sweat lodges” or “sweat houses” of Native Americans. These houses represent special-purpose structures for sweat bathing, which could (and can) combine ritual, social, and healing purposes, and heated stones aided in sustaining high temperatures during the bath (e.g., Custer 2017; Hrynick and Betts 2014; MacDonald 1988).

Different heating systems and methods for retaining heat developed through time and in different parts of the world. In Asia, for example, the Korean ondol developed from a simple hearth surrounded by stones or other heat-retaining material around 3000 bce to a floor heating system with an external furnace around 1000 ce (Yeo, Yang, and Kim 2003). The Roman hypocaust represents a similar heating system. It is traditionally attributed to Sergius Orata, who lived in the 1st century bce, but may have developed from older Greek constructions (e.g., Fagan 2001). The design of a hypocaust varies depending on the scale of the object to be heated, but it generally consists of one or more furnaces generating steam or heat for smaller or larger rooms or even buildings (e.g., McParland et al. 2009). Modern heating systems and energy sources later replaced heat from a fireplace as the most common heat producer in large parts of the world, but open fire is still in use in many parts of the world. Indeed, in 2016, the burning of biofuel and waste was responsible for 9.8 percent of the world energy production according to the International Energy Agency (2018).

Fire for Light

Fire provides light. Humans could thus expand the daylight and this gave people more time for working as well as socializing and creating social bonds (Wiessner 2014, see e.g., Gowlett 2016). Portable light enabled humans to explore dark areas. For example, the use of portable or fixed torches has been considered essential to painting in the interior of dark caves in the Palaeolithic (see, e.g., Medina-Alcaide, Sanchidrián Torti, and Zapata Peña 2015; Théry-Parisot and Thiébault 2005). Two well-known examples are the caves Lascaux and Chauvet in France (e.g., De Beaune 2003; De Beaune and White 1993).Torch marks or smears are indeed known from cave sites all over the world (e.g., overview in Vandevelde et al. 2018, table 1). The use of artificial light and its social and economic implications has received relatively little attention in archaeological research (Griffiths 2016). Nevertheless, it is clear that fire used for light was crucial to many aspects of prehistoric life. A brief overview of two examples of artificial light sources, namely, the lamp and the candle, follows here.

A lamp generally consists of (1) a container or surface with fuel and a wick and (2) a handle, butt, or area for holding and carrying the device (see, e.g., definition in De Beaune 1987). Fat-burning lamps made on natural or hand-made cavities in rock slabs are known from approximately 40,000 years ago (De Beaune 1987; Papadopoulos et al. 2017). Lamps would later be made of various materials in different times and places. For example, ceramic lamps were common in the Mediterranean from c. 500 bce, but similar lamps of stone possibly developed even earlier (Griffiths 2016, e.g., Forbes 1958). The use of lamps could have important societal and economic impacts; for instance, lamps are associated with generating a need for large-scale olive oil production, allowing shops and workshops to stay open longer, and contributing to structural growth in ancient Roman cities such as Pompeii (e.g., Griffiths 2016 and references therein).

A candle consists of a piece of wax or tallow around a central wick and can be portable or placed in stationary holders. There is evidence that humans had access to or knowledge of wax or other material for making candles long before there is any direct evidence of candles. For instance, potential honey hunting is known from Palaeolithic and Mesolithic cave art in Europe and Asia (e.g., Crane 1983), although it is improbable that one can collect sufficient beeswax for candle production from wild colonies (Pattinson 2012, 240). The sun temple of Neuserre at Abu Ghorab, Egypt, dated to approximately 2400 bce, contained the oldest depicted scene of beekeeping and honey handling. The scene, which has been removed from the temple and placed in Berlin, shows that beekeeping was already well developed by that time (Crane 1983). Egyptian depictions of the use of candles in funeral processions are, however, more recent (Griffiths 2016), and the candles depicted may also have been made of material other than beeswax.

In contrast, access to beeswax appears in some written sources to have been one of the main reasons for beekeeping in China in the third century ce (Pattinson 2012). References to beeswax candles are rare in Chinese sources, which nevertheless contain an early record of candles: Emperor Gao of the Han is said to have received beeswax candles in 202 bce and was grateful for the gift, as it was considered rare (Ma, Martinón-Torres, and Li 2015; Pattinson 2012, 240). There is also direct evidence for beeswax in the Chinese archaeological record as beeswax was identified through FT-IR and spectroscopy of items from the Mausoleum M1 of the King of Jiangdu (202 bce–8 ce), China (Ma, Martinón-Torres, and Li 2015). Nonetheless, Ma and colleagues (2015) point out that the wax was probably fuel for lamps, not candles. However, an early example of beeswax candle production is found in the archaeological record from a different part of the world, namely, the site of Sagalassos, Turkey. Beeswax on late Roman (5th–7th centuries ce) cooking pot sherds from the site was identified through mass spectroscopy, and the presence of beeswax is an indication that it was purified in the pots and used for candles (Kimpe, Jacobs, and Waelkens 2002). Candles and other artificial light eventually played important parts in religious or spiritual ceremonies as well as other areas of life (see, e.g., Papadopoulos and Moyes 2017 for an overview) and still have a place in modern homes.

Fire for Cooking

Fire aids food processing. For instance, fish and meat can be dried and smoked by a fire. This practice can be difficult to recognize in the archaeological record, but cut marks suggesting fileting at Blombos Cave, South Africa, 72,000–76,000 years ago is one example of indications of meat processing and drying (Reynard and Henshilwood 2019). Cooking or heat-treating food generally increases absorption of nutrients and improves digestion (Wandsnider 1997; Wrangham 2009), and access to cooked food may thus have affected the physical development of modern humans (e.g., Gowlett and Wrangham 2013; Wrangham 2009). The earliest cooking probably consisted of heating or roasting food next to the fire or among embers and can be recognized through archaeological evidence such as combustion features, burnt bone, charred shells, and burnt plant material (e.g., Bentsen and Wurz 2017 and references therein, Bentsen 2014). Several circumstances, such as group size or available technology, can affect the choice of cooking technique in a given group or area (Wandsnider 1997, fig. 1).

Indirect cooking, such as boiling (e.g., Speth 2015 and references therein) as well as use of cooking pits (e.g., Thoms 2008 and references therein), is among the processes associated with large quantities of thermally altered rocks that appear in the archaeological record after thirty thousand to fifty thousand years ago. “Stone boiling” involves dropping heated rocks in a container of liquid and is considered the earliest boiling method. Nevertheless, Speth (2015) argues that perishable containers, such as skins, containing liquid could be placed directly over a fire to induce boiling before the invention of stone boiling. Boiling among hunter-gatherers in different parts of the world is associated with marrow extraction or grease rendering (e.g., Binford 1978; Brink and Dawe 2003; Manne 2012; Nakazawa et al. 2009; Outram 2001), which can sometimes be recognized through percussion marks on bone (e.g., Outram 2001; Reynard and Henshilwood 2019). However, more work is needed to recognize early boiling through other means than heat-affected stones (Speth 2015).

Cooking pits encompass a range of features that include shallow or deeper pits, sometimes covered with soil or sediments during cooking, and are heated in various ways. For example, a simple fire can be made in the pit or heated rocks can be placed in it to induce slow cooking. Food can be roasted, steamed, boiled, or baked in pits, depending partly on the heating method and cooking traditions (e.g., Black and Thoms 2014; Graff 2018; Holdaway, Davies, and Fanning 2017; Thoms 2008, 2009; Wandsnider 1997). Cooking pits were often reused several times and have a wide temporal and geographical distribution (e.g., Black and Thoms 2014; Graff 2018; Holdaway et al. 2017; Wandsnider 1997).

Thermally altered rocks are found in the remains of some cooking pits. However, heat-affected stones can also be found in other contexts at a site, such as in middens or spread on the surface. Furthermore, processes such as steam baths or unintentional heating also produce fire-cracked rocks. Distinguishing between rocks heated in different processes is difficult, as demonstrated by some studies. For example, simple heating can induce different cracking and breakage in rocks than heating and dropping the rocks in water (e.g., Bentsen and Wurz 2017; Brink and Dawe 2003). Nevertheless, the type of breakage and fracturing during heating or cooking also depends on factors such as rock type and heating temperature (e.g., Backhouse and Johnson 2007; Brink and Dawe 2003; Graesch et al. 2014; Speth 2015). Custer (2017) furthermore conducted a large-scale experimental study, including 864 rock samples and forty-one fires, and did not find significant differences between rocks for boiling and rocks heated for other purposes. It is thus important to conduct studies of locally available raw material to understand if and how one may distinguish different processes leading to thermal alteration in rocks.

Some information on fire use for cooking can be gained through analyses of the food remains. For example, bone may be broken into smaller segments for boiling, which affect fracture patterns and size (Gifford-Gonzalez 1989). The classical experimental study by Shipman and colleagues (1984) demonstrated, however, that major heat-induced changes in color and bone morphology occurs at temperatures above 285°C. It can be difficult to reach 100°C when stone boiling (e.g., Graesch et al. 2014) and meat may insulate bones from heat (e.g., Shipman, Foster, and Schoeninger 1984). Inferring cooking from bones is, consequently, not straightforward. Nevertheless, a study of human tooth marks on bone, suggesting that there are differences between marks on raw and cooked bone (Romero, Díez, and Saladié 2016), shows that there are avenues to explore to further our understanding of cooking and its effect on bones.

There are several other methods and find categories that can contribute to the understanding of fire use for cooking. Mass spectroscopy on pot sherds or archeobotanical analyses can, for example, lead to insight about different food categories as well as cooking techniques (e.g., Evershed et al. 2008; Graff 2018; Henry, Brooks, and Piperno 2014; Kimpe, Jacobs, and Waelkens 2002). Several researchers have examined cooking from various perspectives (e.g., Graff 2018 and references therein), leading to knowledge about how the use of fire for cooking changed over time and in different areas. One example is the changes brought on by the development of pottery and agriculture when crops with different properties were cultivated in different areas. With agriculture, bread baking became predominant in the Mediterranean area, while boiling porridge and fish stews became more important in sub-Saharan Africa (e.g., Haaland 2007). Furthermore, the social and ritual aspects of fire use are emphasized through the feasting and associated meal sharing that occurred in different forms and in different areas through time (see, e.g., Dietler and Hayden 2010; Graff 2018). Space does not allow for further description of all the different aspects of fire use for cooking, but the topic has been at the heart of archaeological research for decades, and new knowledge is being continually produced (see, e.g., overview in Graff 2018).

Fire as a Tool

Fire offers protection. Indeed, safety and defense against predators has been listed as one of the earliest uses of fire (e.g., Alperson-Afil and Goren-Inbar 2010; Clark and Harris 1985). Wild animals are afraid of fire, which can be used to keep them at bay (e.g., with a campfire) as well as for support when hunting. Using fire to drive game animals in a desired direction is a very common hunting method (Scherjon et al. 2015) and was used periodically by Native Americans to drive bison over cliffs or as a political tool to drive herds away from other hunting groups (Speth 2017). Such game-driving fires may be difficult to recognize in the landscape, and the antiquity of the practice has been debated (see, e.g., discussion in James 1989).

Forming the landscape through controlled burning is another practice that may have started very early. It has been suggested, for instance, that early modern humans at Klasies River main site, South Africa, used fire to promote the growth of geophytes (Deacon 1993). There are ethnographic accounts from modern contexts of hunter-gatherer land management through fire to stimulate growth of certain plants, clear the ground, or get rid of snakes and other dangers (e.g., Mallol et al. 2007; Parsons 2015; Scherjon et al. 2015). Nevertheless, it is difficult to establish how common it was to use fire for land management in prehistory. An analysis of charcoal from deep-sea cores taken outside southern Europe did not reveal major changes in the natural fire regimes from around forty thousand to ten thousand years ago, suggesting that fire was not habitually used to control the landscape as modern humans colonized Europe (Daniau, d’Errico, and Sánchez Goñi 2010). This kind of fire use would perhaps only have become important later, as we know that slash and burn agriculture has been practiced since the Neolithic (e.g., Carcaillet 1998).

Tools for hunting and other activities can be produced or improved through the use of fire. For example, heat treatment of silcrete or flint can improve knapping properties and make it easier to flake (e.g., Brown et al. 2009; Domański et al. 2009; Mourre, Villa, and Henshilwood 2010; Schmidt et al. 2012, 2013). It has been suggested that heat treatment of rocks was a common practice in southern Africa at ~72,000 years ago (Brown et al. 2009), although the heating method is debated (e.g., Schmidt et al. 2013). Different types of adhesives or glue for hafting tools can also be produced and dried with the help of a campfire (Cnuts, Tomasso, and Rots 2018; Lombard 2005; Sahle 2019; Wadley 2005; Wadley, Hodgskiss, and Grant 2009). Stone tool production thus benefits both from the light and the heat of a fire in making it easier to see while producing the tool, enabling learners to observe and learn from skilled producers, as well as contributing to the transformation of raw materials into a finished product.

The production of ceramics represents a new step in the use of fire as a tool. Excavations at the European site Dolni Vestonice has revealed several figurines, some from contexts nearly thirty thousand years old, which are considered some of the earliest examples of ceramics (Vandiver et al. 1989). The invention of pottery involves not only the introduction of firing technology and new containers, but also introduces a production sequence with several steps and, in some cases, a specialist profession or activities associated with specific social identities in a group (Gosselain 1992, 2000; Jeffra 2015).

Transforming metal to tools is a complex process involving advanced use of fire technology. The production and use of metal tools was integrated in society, had both social and technological impact, and can be viewed as an early form of globalization involving contact and trade between many new partners from different areas (Chirikure 2015). A full review of the origins and development of metallurgy in the world is beyond the scope of this article. However, metallurgy has, since its earliest attempts around twelve thousand years ago, represented both negative impacts, such as warfare and destruction, and positive impacts such as innovation and artistic creativity (Kaufman 2018).

Concluding Remarks

Fire is one of the oldest technologies of humankind, used for many diverse activities. This technology enabled more light and more time to work, as well as a meeting point for social interaction and learning. Fire technology continued to shape us through its use in new technologies, such as pottery, enabling new social and political identities based on technological knowledge. We may never be able to pinpoint the moment in time when humans learned to control fire, but we are already uncovering many of the processes and interactions that constitute fire technology. A broader understanding of what fire technology is, how it is used, and how it impacts humans using it will also provide insight into humans in general and the development of our societies.