Creatures of theFlame: Light andHeat in HumanEvolutionFire: The Spark That Ignited HumanEvolution. By Frances D. Burton (2009)Albuquerque: University of New MexicoPress. 245 pp. $34.95. ISBN 978-0-826-34646-9.

Catching Fire: How Cooking Made UsHuman. By Richard Wrangham (2009)New York: Basic Books. 315 pp. $26.95.ISBN 978-0-465-01362-3.

To the ancient Greeks, fire and thebeginning of humanity were inextri-cably linked by the actions of Prome-theus, who created humans fromearth and water. In a heroic under-taking, he gave them fire that hestole from Zeus, who had withheld itfrom the mortals. For this transgres-sion, Zeus strapped Prometheus to arock where eagles would devour hisliver every day. Every night his liverwould regenerate, ensuring both hisimmortality and his endless dailysuffering. Prometheus lived anotherday only to face another onslaught ofeagles consuming his vital organ.For us mere mortals, the origin of

fire may be more mundane in itsbeginnings, but it is equally epic inits consequences. Sigmund Freud1

offered a bizarre psychoanalytictheory that tied the origins of civiliza-tion to the control of fire. Freudclaimed that civilization had its ori-gins when men resisted their primalurge to extinguish fire with a streamof their urine. In a footnote in Civili-zation and Its Discontents, he stated,‘‘It is as though primal man had thehabit, when he came in contact withfire, of satisfying an infantile desireconnected with it, by putting it outwith a stream of urine . . .. The firstperson to renounce this desire andspare the fire was able to carry it off

with him and subdue it to his ownuse. By damping down the fire of hisown sexual excitation, he had tamedthe natural force of fire. This greatcultural conquest was thus the rewardfor his renunciation of instinct.’’

Richard Wrangham and FrancesBurton take other perspectives on theorigins of fire, with quite different evo-lutionary outcomes. Wrangham con-siders heat generated by fire and itsrelationship to cooking as a drivingforce in the evolution of hominins.Burton focuses on the light emittedfrom the campfire that extends the dayof the hominins, altering forever thehormonal cycles that depend on lightand darkness. The control of fire,according to Wrangham, ‘‘made ushuman’’; for Burton, it ‘‘ignited humanevolution.’’

For Burton, this transformationbegan about six million years ago,when the light of the campfire led tothe divergence of hominins from ourchimp ancestor. Her thesis on the ori-gin of fire and the impact of light onhuman biology is not grounded indirect evidence, but rather is con-structed from a series of speculativeassumptions that the control of fireexisted six million years ago and thatthe light from campfires was strongenough to affect the hormonal levels ofthe hominins. She foregrounds heranalysis with a discussion of how ourancestors identified the beneficial usesof fire and provides a brief descriptionof the ecological role of fire in the Afri-can savanna. Burton even considersthe relationship between nonhumanprimates and fire. She considers apeand monkey analogues to further builda picture of what early hominins’behavior might have been like whenexposed to the light of fire. Burton con-siders the fact that the known archeo-logical evidence of fire does not supporther argument, yet she speculates thatcontact with fire was the transformingevent in the origin of hominins.

The crux of Burton’s novel interpre-tation suggests that the light of camp-fires extended the day, resulting in aphase shift that increased the body’sexposure to light, thus decreasingmelatonin levels in the body. Thischange in melatonin had repercus-

sions throughout hormonal systems,causing an impact on the patterns ofbrain activity that were a critical forceaccelerating the evolutionary trajec-tory of our species. The divergence ofthe hominins was the result of a cas-cade of psychophysiological changesthat accelerated behavioral, endocri-nological, socioendocrinological, andepigenetic changes. She argues thatboth the rates and patterns of growth,as well as the regulation and activa-tion of genes, accelerated the ‘‘proc-esses of mind, body, disease, and soci-ety,’’ thus differentiating homininsfrom our primate ancestors and trans-forming humanity forever.Burton and Wrangham share a

model in which ancestral apes had toovercome their innate fear of fire. Giventhe positive features of fire, it is not dif-ficult to speculate how our ancestorsmight have overcome this fear. Fireprovidedwarmth, whichwas both com-forting and useful in warding off preda-tors. Burton and Wrangham hypothe-size that the early hominins playfully‘‘dared’’ each other by picking up andbrandished firebrands to frighten eachother. They eventually realized that thisbehavior could be used to ward off theanimals that preyed on them. Fireallowed them to move out of the treesand sleep on the ground with fire keep-ing the predators at bay.Burton suggests that our ancestors

would have realized that by puttingtwigs onto a smoldering fire, theycould keep it going. In addition, sheargues that wildfires attracted pyro-phlius (fire-loving) insects that wereconsumed by the flames. The desir-ability of these delicacies found insmoldering fire would have forcedour ancestors to overcome their fearof the heat or flames.Pruetz and LaDuke’s2 recent report

on savanna chimpanzees’ (Pan troglo-dytes versus) encounters with wildfiresis relevant to Burton and Wrangham’sspeculation on the control of fire byour ancestors. These authors see simi-larities in great apes’ and humans’reaction to fire. The chimpanzees atFongoli, Senegal, calmly monitoredthe wildfire and were able to antici-pate its movements and change theirbehavior accordingly. Preutz and

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VVC 2010 Wiley-Liss, Inc.DOI 10.1002/evan.20273Published online in Wiley Online Library(wileyonlinelibrary.com).

Evolutionary Anthropology 19:158–160 (2010)

LaDuke claim that this ability to con-ceptualize the behavior of the fire maybe a synapomorphic trait in humansand chimpanzees. Even rhesus maca-ques on the Island of Cayo Santiagohave been observed searching forcoconuts in the hot ashes of nearlyexpired fires, reaching in and testingto see if they had cooled enough to eat(Sarah Gouzoules, personal commu-nication). The animals did not seemto be interested in the burning fire,paying attention only when the flameshad died down.In Catching Fire: How Cooking Made

Us Human, Wrangham argues that thecontrol of fire for cooking food was thekey for the evolution of a larger-brainedHomo erectus about 1.9 millionyears ago. Cooking, rather than meateating, as proposed by some anthropol-ogists, was the major stimulus for theemergence of hominins.3 However, asengaging as Burton and Wrangham’shypotheses are, timing complicatestheir arguments. There are some am-biguous indications of the use of fireabout 1.6 million years ago, with indis-putable evidence of controlled fires inthe form of hearths between 800,0004

and 250,000 years ago.5,6 However,finding the evidence of cooking is diffi-cult to distinguish in the archeologicalrecord. It was almost a million years af-ter the arrival of Homo erectus wherethere is compelling evidence of fire.Even though this incongruity is a prob-lem for Wrangham, he has a solutionto it: ‘‘But though we cannot solve theproblem of when cooking began byrelying on the faint traces of ancientfire, we can use biology instead.’’Unfortunately, the case that Wrang-

ham makes for biological evidence ofcooking as the key to the emergence ofHomo erectus is circumstantial andtautological. Wrangham relies on theobservable reduction of the dentitionand anatomical changes in the handrelated to the loss of climbing adapta-tion. He suggests that the significantincrease in brain size that marked theemergence of Homo erectus was theresult of an energy dividend derivedfrom cooking food. As with the expen-sive-tissue hypothesis,7 the energy forexpansion of the brain resulted inreduction in the size of the gut, withchanges in the length of small and largeintestines. Wrangham accepts the ex-

pensive-tissue hypothesis with the ca-veat that there were two phases in theexpansion of the brain, not the singlestage that Aiello andWheeler modeled.

Wrangham’s conjecture is that thedecrease in the length of the largeintestine, increase in the stomach andsmall intestine, and expansion of thebrain occurred at the time of the emer-gence of Homo erectus at 1.9 millionyears ago. He suggests that an earlierphase in cranial expansion came withthe appearance of the habilines whowere still eating their foods raw.

Wrangham has a special antipathyfor the raw food movement (10% ofthe text is a rant against raw food fad-dism). Raw food followers will not eatfood heated above 118 degrees Fahr-enheit, claiming the temperaturedestroys the food’s ‘‘life force.’’ Hecites a number of problems for thoseon a raw food diet. He describes theBBC’s Evo-Devo experiment in whichseven subjects persisted on a raw fooddiet for 12 days, resulting in some pos-itive changes in health indicators andsignificant weight loss.8 While choles-terol levels and blood pressuredecrease, half of the women who havebeen on a raw diet lost enough weightto become amenorrheic, ceasing toovulate, an evolutionary dead end.

Cooking has a number of significantadvantages. It has always been knownto makes food safer by killing patho-gens, thus reducing spoilage. But forWrangham, there is another advantagethat has even greater evolutionarysignificance. Cooking increased theamounts of energy obtained from food,which reduces chewing time. Peopleeating cooked food chew for about 36minutes in a 12-hour day. If humanswere consuming an ape’s raw fooddiet, they would have to spend 42% ofa 12 hour day (five hours) masticating.

Wrangham’s cooking hypothesis hasbeen a significant part of the scientificliterature for more than a decade, butCatching Fire is a very readable accountof previous research that is worthy ofour attention. Wrangham argues thatcooking makes inedible plants edibleand that cooked foods are preferred byhumans and even captive apes. Cook-ing breaks down the skin, softens cellu-lose, denatures toxins, and reduces acomplex protein that enhances sweet-ness and increased the caloric intake of

early hominins. In essence, this is ‘‘out-sourcing digestion,’’ or a technologicalmethod of ‘‘predigesting’’ foods.9 Apescan finely discriminate levels of sugarin food,10 which are enhanced by cook-ing, which increases the susceptibilityof starch to amylase degradation andthus increases sweetness.11

Once the evolutionary changesbecame embedded in the anatomy ofhumans, the ability to chew and digestfibrous foods became limited bychanges in the chewing apparatus.Smaller teeth and changes in the intes-tinal tract resulted in faster gut pas-sage rate and digestion of variousfoods. These changes would have even-tually reduced hominins’ abilities todigest uncooked fibers and detoxifysecondary compounds, limiting poten-tial dietary items and creating a de-pendence on energy dense foods,whichWrangham claims would be fur-ther enhanced by cooking.In contrast, Wrangham and others

have argued that plants, fruits, oil-rich seeds, and tubers were alsoessential features of the early homi-nin diet, especially because plant ma-terial makes up 87% to 99% of pri-mate diets.12 While others have madethe case that high-density foods suchas seeds and tubers would be an al-ternative to meat eating, Wranghamaccepts this interpretation, but addsthat cooking improved the digestibil-ity of these energy-dense foods.According to Wrangham, cooking

not only resulted in changes in anat-omy, but also had an impact onhuman psychology and society. Inone of his more controversial pro-posals, Wrangham argues that cook-ing freed women’s time, but trappedthem into a subservient role. Femalecooks need males to help guard thefood from hungry males, forcingwomen to bond with a specific male.Marriage, in Wrangham’s scenario, isan economic contract that is a ‘‘prim-itive protection racket’’ that placedwomen in a male-dominated society.There is an unfortunate aspect of the

cooking hypothesis in which Wrang-ham sees cooking as the source of allthings cultural. In his analysis of theobesity epidemic, Wrangham suggeststhat because cooking increases avail-able energy, there is a possibility ofover-consumption. In his assessment

BOOK REVIEW Creatures of the Flame: Light and Heat in Human Evolution 159

of cooking as the source of over-nutri-tion, Wrangham, in the words of Mar-vin Harris, ‘‘quits early.’’ Cooking is animportant element in the processing ofenergy-dense foods that are part of theAmerican food system. What Wrang-ham fails to consider is that we have anindustrial food system that can deliverenergy-dense foods to the massesinexpensively.13 Cooking cannot fullyexplain the introduction of a high-den-sity food such as KFC’s Double Down.For $4.99, Kentucky Fried Chickenoffers the breadless ‘‘Double Down’’that is made with two Original Recipefried chicken filets, two strips of bacon,a slice of pepper jack cheese, a slice ofSwiss cheese, and dollop of the Colo-nel’s secret sauce. In its advertisement,KFC says the Double Down is so bigthat there is no room for the bread.The Double Down supplies more thanthe recommended allowance of fat(124%), saturated fat (117%), choles-terol (105%), sodium (125%), and pro-tein (194%), as well as 61% of the dailyrecommended calorie intake.14

The industrial food system can pro-duce enormous quantities of energy-dense foods such as refined sugar.Americans consume 22.2 teaspoons ofadded sugar each day, representing355 additional calories. Put into abroader perspective, this representsthe equivalent of more than two-and-a-half tons (5,892 pounds) of addedsugar over the course of an individu-al’s lifetime. In caloric terms, this rep-resents ten million calories, whichwould translate to 2,946 pounds ofadded weight if the energy were notexpended. In 2009, the world produc-tion of sugar was 3.1 trillion pounds,of which 61 billion pounds were pro-duced in the United States.15

Added to the potential to delivervast quantities of energy-rich foodsis an economic system in which largesegments of the population are hav-ing financial and time constraints.There is a relationship between obe-sity and socioeconomic factors thatis related to dietary energy densityand energy cost.16 Refined grains,sugars, and fats are among the low-est-cost sources of dietary energy.Energy-dense foods are inexpensive;they taste good and are convenient.The more nutrient-dense lean meats,fish, fresh vegetables, and fruit gen-

erally cost more. An inverse relation-ship between the energy density offoods (kilojoules per gram) and theirenergy cost (dollars per megajoule)means that the more energy-densediets are associated with lower dailyfood consumption costs and there-fore may be an effective way for indi-viduals to save money. The economicdecision to use high-energy-densefood may have economically burden-some biological consequences.16,17

Catching Fire is unburdened by in-text references, but has an annotatedbibliography that accounts for 43 ofthe 315 total pages (the text comprises208 pages). The references keyed topages in the text provide ample cita-tions for Wrangham’s theory, as wellas enjoyable digressions that helpmake his case for the cooking hypoth-esis. In addition to his thoroughscholarship, we are treated to Wrang-ham’s nimble mind as he speculateson various related issues.

Although I was already familiarwith Wrangham’s cooking hypothe-sis, I found this an engaging book.Wrangham has a wonderful stylethat keeps one tied to the pages. Onthe other hand, since Burton neverprovides a convincing argument thatthe light of the campfire affectedhuman physiology or changed thecourse of human evolution, it is amore ponderous reading experience.

Wrangham and Burton offer specu-lative essays on the origin of human-kind, which, while interesting, aremissing a critical piece of evidencethat can link the control of fire to theonset of the evolutionary changesoriginating from fire’s heat and light.Both authors are well aware that theirhypotheses are missing the crucial pi-ece of evidence. The archeological evi-dence of fire occurs much later thando the anatomical and behavioral fea-tures that they use as evidence of fire.

The impact of fire on humanity pro-duced more heat than light. The heatof the cooking hypothesis seems morecompelling than does the light of Bur-ton’s hypothesis. Both essays remindone of trying to light a campfire thatflickers for a while, only to sadlyextinguish itself. But we can imaginea roaring fire that lights up the nightsky. Metaphorically, Burton’s andWrangham’s hypotheses never reach

the roaring fire stage, but they do pro-vide us a vision of what could havebeen. Even with the failure to maketheir cases, we owe Burton andWrangham a debt of gratitude forforcing us to consider alternatives tothe accepted wisdom.

REFERENCES

1 Freud S. 1961. Civilization and Its discontents.

New York: W. W. Norton.

2 Pruetz JD, LaDuke TC. 2010. Reaction to fireby savanna chimpanzees Pan troglodytes verusat Fongoli, Senegal: conceptualization of ‘‘firebehavior’’ and the case for a chimpanzee model.Am J Phys Anthropol 141:646–650.

3 Bunn HT. 2007. Meat made us human. In:Unger P, editor. Evolution of human diet: theknown, the unknown and the unknowable. Oxford:Oxford University Press. p 191–203.

4 Goren-Inbar N, Alperson N, Kislev ME, Sim-choni O, Melamed Y, Ben-Nun A, Werker E. 2004.Evidence of hominin control of fire at GesherBenot Ya‘aqov, Israel. Science 304:725–727.

5 Gibbons A. 2007. Food for thought. Science316:1558–1560.

6 Preece RC, Gowlett JAJ, Parfitt SA, BridglandDR, Lewis SG. 2006. Humans in the Hoxnian:habitat, context and fire use at Beeches Pit,West Stow, Suffolk, UK. J Quaternary Sci21:485–496.

7 Aiello LC, Wheeler P. 1995. The expensive-tis-sue hypothesis: the brain and the digestive sys-tem in human and primate evolution. CurrAnthropol 36:199–221.

8 Fontana L, Shew JL, Holloszy JO, Villareal DT.2005. Low bone mass in subjects on a long-termraw vegetarian diet. Arch InternMed 165:684–689.

9 Milton K. 2000. Hunter-gatherer diets: a dif-ferent perspective. Am J Clin Nutr 71:665–667.

10 Hladik CM, Simmen B. 1996. Taste perceptionand feeding behavior in nonhuman P\primatesand human populations. Evol Anthropol 5:58–71.

11 Svihus B, Uhlen AK, Harstad OM. 2005. Effectof starch granule structure, associated components,and processing on nutritive value of cereal starch: areview. Anim Feed Sci Technol 122:303–320.

12 Milton K. 2003. The critical role played byanimal source foods in human (Homo) evolu-tion. J Nutr 133:3886S–3892S.

13 Armelagos GJ. 2010. The omnivore’s dilemma:the evolution of the brain and the determinants offood choice. J Anthropol Res 66:161–186.

14 Parry C. 2009 KFC tests out new bunlessburger to rave reviews in America’s heartland.Vancouver, Sun, August 25, 2009.

15 Tian Y. 2009. Global sugar-production defi-cit to widen, ISO says (Update1). Bloomberg.com. http://www.bloomberg.com/apps/news?pid¼20601087&sid¼antxF2zirii4.

16 Drewnowski A, Darmon N. 2005. Foodchoices and diet costs: an economic analysis.J Nutr 135:900–904.

17 Drewnowski A, Darmon N. 2005. The econom-ics of obesity: dietary energy density and energycost. Am J Clin Nutr 82(suppl 1):265S–273S.

George J. ArmelagosEmory University

Atlanta, GA 30322

E-mail: antga@emory.edu

160 Armelagos BOOK REVIEW