Cultural innovation Uses of fire by early humans The discovery of fire provided early
hominids with a range of uses. Its warmth kept them alive during low nighttime temperatures in colder environments, allowing geographic expansion from
tropical and
subtropical climates to
temperate areas. Its blaze warded off predatory animals, especially in the dark. Fire also played a major role in changing food habits.
Cooking allowed a significant increase in meat consumption and calorie intake. Fire was even used in manufacturing
tools for hunting and butchering. Hominids also learned that starting bushfires to burn large areas could increase
soil fertility and clear terrain to make hunting easier. Evidence shows that early hominids were able to corral and
trap prey animals using fire. Fire was used to clear out caves before living in them, helping to begin the use of shelter. The many uses of fire may have led to specialized social roles, such as the separation of cooking from hunting. The control of fire enabled important changes in human behavior, health, energy expenditure, and geographic expansion. After the loss of body hair, hominids could move into much colder regions that would have previously been uninhabitable. Evidence of more complex management to change
biomes can be found as far back as 200,000 to 100,000 years ago, at minimum.
Tool and weapon making Fire allowed major innovations in tool and weapon manufacture. Evidence dating to roughly 164,000 years ago indicates that early humans in
South Africa during the Middle Stone Age used fire to alter the mechanical properties of tool materials applying heat treatment to a fine-grained rock called
silcrete. The heated rocks were then tempered into crescent-shaped blades or arrowheads for hunting and butchering prey. This may have been the first time that
bow and arrow were used for hunting, with far-ranging impact.
Art and ceramics Fire was used in the creation of art. Archaeologists have discovered several 1- to 10-inch
Venus figurine statues in Europe dating to the
Paleolithic, several carved from stone and ivory, others shaped from
clay and then fired. These are some of the earliest examples of
ceramics. Fire was also commonly used to create
pottery. Although pottery was formerly thought to have begun with the Neolithic around 10,000 years ago, scientists in
China discovered pottery fragments in the
Xianrendong Cave that were about 20,000 years old. During the
Neolithic Age and agricultural revolution about 10,000 years ago, pottery became far more common and widespread, often carved and painted with simple linear designs and geometric shapes.
Social development and nighttime activity Fire was an important factor in the expansion and development of early hominid societies. One impact fire might have had was
social stratification. The power to make and wield fire may have conferred prestige and social position. Evidence of large hearths indicates that the majority of nighttime was spent around the fire. The increased social interaction from gathering around the fire may have fostered the development of language. The modern human's waking day is 16 hours, while many mammals are only awake for half as many hours. Critics of the hypothesis argue that cooking with controlled fire was insufficient to start the increasing brain size trend. The cooking hypothesis gains support by comparing the nutrients in
raw food to the much more easily digested nutrients in cooked food, as in an examination of protein ingestion from raw vs. cooked egg. Scientists have found that among several primates, the restriction of feeding to raw foods during daylight hours limits the metabolic energy available. Genus
Homo was able to break through the limit by cooking food to shorten their feeding times and be able to absorb more nutrients to accommodate the increasing need for energy. In addition, scientists argue that the
Homo species was also able to obtain nutrients like
docosahexaenoic acid from algae that were especially beneficial and critical for brain evolution. The cooking process enabled early humans to detoxify food and access these resources. Besides the brain, other human organs also demand a high
metabolism. Cooking could also kill
parasites, reduce the amount of energy required for chewing and digestion, and release more nutrients from plants and meat. Due to the difficulty of chewing raw meat and digesting tough proteins (e.g.,
collagen) and carbohydrates, the development of cooking served as an effective means of processing meat and enabling its consumption in larger quantities. With its high caloric density and important nutrient content, meat became a staple in the diet of early humans. By increasing digestibility, cooking allowed
hominids to maximize the energy gained from consuming foods. Studies show that caloric intake from cooking starches improves by 12–35%, and 45–78% for protein. As a result of the increases in net energy gain from food consumption, survival and reproductive rates in hominids increased. Through lowering food toxicity and increasing nutritive yield, cooking allowed for an earlier weaning age, permitting females to have more children. In this way, too, it facilitated population growth. It has been proposed that the use of fire for cooking caused
environmental toxins to accumulate in the placenta, leading to a species-wide taboo on
human placentophagy around the time of the mastery of fire. Placentophagy is common in other primates.
Biological changes Before their use of fire, the hominid species had large
premolars, which were used to chew harder foods, such as large seeds. In addition, due to the shape of the molar cusps, the diet is inferred to have been more leaf- or fruit-based. Probably in response to consuming cooked foods, the molar teeth of
H. erectus gradually shrank, suggesting that their diet had changed from more challenging foods such as crisp root vegetables to softer cooked foods such as meat. Cooked foods further selected for the differentiation of their teeth and eventually led to a decreased jaw volume with a variety of smaller teeth in hominids. Today, a smaller jaw volume and teeth size of humans is seen in comparison to other primates. Due to the increased digestibility of many cooked foods, less digestion was needed to procure the necessary nutrients. As a result, the
gastrointestinal tract and organs in the
digestive system decreased in size. This is in contrast to other primates, in which a larger digestive tract is needed to ferment long carbohydrate chains. Thus, humans evolved from the large colons and tracts that are seen in other primates to smaller ones. According to Wrangham, fire control allowed hominids to sleep on the ground and in caves rather than in trees, and led to more time spent on the ground. This may have contributed to the evolution of
bipedalism, as such an ability became increasingly necessary for human activity.
Criticism Critics of the hypothesis argue that, while a linear increase in brain volume in the genus
Homo is observed over time, the advent of fire control and cooking does not meaningfully contribute to the data. Species such as
H. ergaster existed with large brain volumes during periods with little to no evidence of cooking fire. Little variation exists in the brain sizes of
H. erectus dated from periods of weak and strong evidence for cooking. Studies such as this and others have led to criticisms of the hypothesis that state that the increases in human brain size occurred well before the advent of cooking due to a shift away from the consumption of nuts and berries to the consumption of meat. Other anthropologists argue that the evidence suggests that cooking fires began in earnest only 250,000 BP, when ancient hearths, earth ovens, burned animal bones; flint appeared across Europe and the Middle East. == See also ==