Diamond, Jared, Guns, Germs and Steel. A shorthistorv of evervbodv for the last 13,000 vears. 1997 myown book scans preservedIn this Pulitzer Prize-winning book, Jared Diamond argues thatboth geography and the environment played major roles indetermining the shape oI the modern world. This argument runscounter to the usual theories that cite biology as the crucial Iactor.Diamond claims that the cultures that were Iirst able to domesticateplants and animals were then able to develop writing skills, as well asmake advances in the creation oI government, technology, weaponry,and immunity to disease Prologue: Yali's Question: The regionallydiIIering courses oI history 13Ch. 1 Up to the Starting Line: What happened on allthe continents beIore 11,000 B.C.? 35Ch. 2 A Natural Experiment oI History: Howgeography molded societies on Polynesian islands 53Ch. 3 Collision at Cajamarca: Why the Inca emperorAtahuallpa did not capture King Charles I oI Spain 67Ch. 4 Farmer Power: The roots oI guns, germs, andsteel 85Ch. 5 History's Haves and Have-Nots: GeographicdiIIerences in the onset oI Iood production 93Ch. 6 To Farm or Not to Farm: Causes oI the spreadoI Iood production 104Ch. 7 How to Make an Almond: The unconsciousdevelopment oI ancient crops 114Ch. 8 Apples or Indians: Why did peoples oI someregions Iail to domesticate plants? 131Ch. 9 Zebras, Unhappy Marriages, and the AnnaKarenina Principle: Why were most big wild mammal species neverdomesticated? 157Ch. 10 Spacious Skies and Tilted Axes: Why didIood production spread at diIIerent rates on diIIerent continents?176Ch. 11 Lethal GiIt oI Livestock: The evolution oIgerms 195Ch. 12 Blueprints and Borrowed Letters: Theevolution oI writing 215Ch. 13 Necessity's Mother: The evolution oItechnology 239Ch. 14 From Egalitarianism to Kleptocracy: Theevolution oI government and religion 265Ch. 15 Yali's People: The histories oI Australia andNew Guinea 295Ch. 16 How China became Chinese: The history oIEast Asia 322Ch. 17 Speedboat to Polynesia: The history oI theAustronesian expansion 334Ch. 18 Hemispheres Colliding: The histories oIEurasia and the Americas compared 354Ch. 19 How AIrica became Black: The history oIAIrica 376Epilogue: The Future oI Human History as aScience 403Acknowledgments 427Further Readings 429Credits 459Index 461P R E F A C EWHY Is WORLD HISTORY LIKE ANONION?THIS BOOK ATTEMPTS TO PROVIDE A SHORT HISTORY OF EVERYbodyIor the last 13,000 years. The question motivating the book is: Whydid history unIold diIIerently on diIIerent continents? In case thisquestion immediately makes you shudder at the thought that you areabout to read a racist treatise, you aren't; as you will see, the answersto the question don't involve human racial diIIerences at all. The book'semphasis is on the search Ior ultimate explanations, and on pushing backthe chain oI historical causation as Iar as possible.Most books that set out to recount world history concentrate onhistories oI literate Eurasia and North AIrican societies. Native societiesoI other parts oI the worldsub-Saharan AIrica, the Americas, IslandSoutheast Asia, Australia, New Guinea, the PaciIic Islandsreceiveonly brieI treatment, mainly as concerns what happened to them verylate in their history, aIter they were discovered and subjugated by westernEuropeans. Even within Eurasia, much more space gets devoted to thehistory oI western Eurasia than oI China, India, Japan, tropicalSoutheast Asia, and other eastern Eurasian societies. History beIorethe emergence oI writing around 3,000 B.C. also receives brieI treatment,although it constitutes 99.9 oI the Iive-million-year history oI thehuman species.10 P REF ACESuch narrowly Iocused accounts oI world history suIIer Irom threedisadvantages. First, increasing numbers oI people today are, quiteunderstandably, interested in other societies besides those oI westernEurasia. AIter all, those "other" societies encompass most oI theworld's population and the vast majority oI the world's ethnic, cultural,and liguistic groups. Some oI them already are, and others are becoming,among the world's most powerIul economies and political Iorces.Second, even Ior people speciIically interested in the shaping oI themodern world, a history limited to developments since the emergence oIwriting cannot provide deep understanding. It is not the case thatsocieties on the diIIerent continents were comparable to each otheruntil 3,000 B.C., whereupon western Eurasian societies suddenly developedwriting and began Ior the Iirst time to pull ahead in other respects as well.Instead, already by 3,000 B.C., there were Eurasian and North AIricansocieties not only with incipient writing but also with centralized stategovernments, cities, widespread use oI metal tools and weapons, useoI domesticated animals Ior transport and traction and mechanicalpower, and reliance on agriculture and domestic animals Ior Iood.Throughout most or all parts oI other continents, none oI those thingsexisted at that time; some but not all oI them emerged later in parts oI theNative Americas and sub-Saharan AIrica, but only over the course oI thenext Iive millenia; and none oI them emerged in Aboriginal Australia.That should already warn us that the roots oI western Eurasiandominance in the modern world lie in the preliterate past beIore 3,000B.C. (By western Eurasian dominance, I mean the dominance oI westernEurasian societies themselves and oI the societies that they spawned onother continents.)Third, a history Iocused on western Eurasian societies completelybypasses the obvious big question. Why were those societies the onesthat became disproportionately powerIul and innovative? The usualanswers to that question invoke proximate Iorces, such as the rise oIcapitalism, mercantilism, scientiIic inquiry, technology, and nastygerms that killed peoples oI other continents when they came into contactwith western Eurasians. But why did those ingredients oI conquest arisein western Eurasia, and arise elsewhere only to a lesser degree or not atall?All those ingredients are just proximate Iactors, not ultimateexplanations. Why didn't capitalism Ilourish in Native Mexico,mercantil-WHY IS W O R L D HI S TORY L I K E AN ONI O N? I Iism in sub-Saharan AIrica, scientiIic inquiry in China, advancedtechnology in Native North America, and nasty germs in AboriginalAustralia? II one responds by invoking idiosyncratic cultural Iactorse.g., scientiIic inquiry supposedly stiIled in China by ConIucianismbut stimulated in western Eurasia by Greek oI Judaeo-Christiantraditionsthen one is continuing to ignore the need Ior ultimateexplanations: why didn't traditions like ConIucianism and the Judaeo-Christian ethic instead develop in western Eurasia and Chinarespectively? In addition, one is ignoring the Iact that ConIucian Chinawas technologically more advanced that western Eurasia until aboutA.D. 1400.It is impossible to understand even just western Eurasian societiesthemselves, iI one Iocuses on them. The interesting questions concern thedistinctions between them and other societies. Answering thosequestions requires us to understand all those other societies as well, sothat western Eurasian societies can be Iitted into the broader context.Some readers may Ieel that I am going to the opposite extreme Iromconventional histories, by devoting too little space to western Eurasia atthe expense oI other parts oI the world. I would answer that someother parts oI the world are very instructive, because they encompass somany societies and such diverese societies within a small geographicalarea. Other readers may Iind themselves agreeing with one revieweroI this book. With mildly critical tongue in cheek, the reviewer wrotethat I seem to view world history as an onion, oI which the modern worldconstitutes only the surIace, and whose layers are to be peeled back inthe search Ior historical understanding. Yes, world history is indeedsuch an onion! But that peeling back oI the onion's layers is Iascinating,challengingand oI overwhelming importance to us today, as we seek tograsp our past's lessons Ior our Iuture. Chapter One: Up To The StartingLine A suitable starting point Irom which to compare historicaldevelopments on the diIIerent continents is around 11,000 B.C.(*)This date corresponds approximately to the beginnings oI village liIein a Iew parts oI the world, the Iirst undisputed peopling oI theAmericas, the end oI the Pleistocene Era and last Ice Age, and thestart oI what geologists term the Recent Era. Plant and animaldomestication began in at least one part oI the world within a Iewthousand years oI that date. As oI then, did the people oI somecontinents already have a head start or a clear advantage over peoplesoI other continents? II so, perhaps that head start, ampliIied over the last 13,000years, provides the answer to Yali's question. Hence this chapter willoIIer a whirlwind tour oI human history on all the continents, Iormillions oI years, Irom our origins as a species until 13,000 years ago.All that will now be summarized in less than 20 pages. Naturally, Ishall gloss over details and mention only what seem to me the trendsmost relevant to this book. Our closest living relatives are three surviving species oI greatape: the gorilla, the common chimpanzee, and the pygmy chimpanzee(also known as bonobo). Their conIinement to AIrica, along withabundant Iossil evidence, indicates that the earliest stages oI humanevolution were also played out in AIrica. Human history, assomething separate Irom the history oI animals, began there about 7million years ago (estimates range Irom 5 to 9 million years ago).Around that time, a population oI AIrican apes broke up into severalpopulations, oI which one proceeded to evolve into modern gorillas,asecond into the two modern chimps, and the third into humans. Thegorilla line apparently split oII slightly beIore the split between thechimp and the human lines. Fossils indicate that the evolutionary line leading to us hadachieved a substantially upright posture by around 4 million yearsago, then began to increase in body size and in relative brain sizearound 2.5 million years ago. Those protohumans are generallyknown as Australopithecus aIricanus, Homo habilis, and Homoerectus, which apparently evolved into each other in that sequence.Although Homo erectus, the stage reached around 1.7 million yearsago, was close to us modern humans in body size, its brain size wasstill barely halI oI ours. Stone tools became common around 2.5million years ago, but they were merely the crudest oI Ilaked orbattered stones. In zoological signiIicance and distinctiveness, Homoerectus was more than an ape, but still much less than a modernhuman. All oI that human history, Ior the Iirst 5 or 6 million years aIterour origins about 7 million years ago, remained conIined to AIrica.The Iirst human ancestor to spread beyond AIrica was Homo erectus,as is attested by Iossils discovered on the Southeast Asian island oIJava and conventionally known as Java man (see Figure 1.1). The oldest Java "man" Iossils--oI course, they may actually havebelonged to a Java woman--have usually been assumed to date Iromabout a million years ago. However, it has recently been argued thatthey actually date Irom 1.8 million years ago. (Strictly speaking, thename Homo erectus belongs to these Javan Iossils, and the AIricanIossils classiIied as Homo erectus may warrant a diIIerent name.) Atpresent, the earliest unquestioned evidence Ior humans in Europestems Irom around halI a million years ago, but there are claims oI anearlier presence. One would certainly assume that the colonization oIAsia also permitted the simultaneous colonization oI Europe, sinceEurasia is a single landmass not bisected by major barriers. That illustrates an issue that will recur throughout this book.Whenever some scientist claims to have discovered "the earliest X"--whether X is the earliest human Iossil in Europe, the earliest evidenceoI domesticated corn in Mexico, or the earliest anything anywhere--that announcement challenges other scientists to beat the claim byIinding something still earlier. In reality, there must be some truly"earliest X," with all claims oI earlier X's being Ialse. However, as weshall see, Ior virtually any X, every year brings Iorth new discoveriesand claims oI a purported still earlier X, along with reIutations oIsome or all oI previous years' claims oI earlier X. It oIten takesdecades oI searching beIore archaeologists reach a consensus on suchquestions. By about halI a million years ago, human Iossils had divergedIrom older Homo erectus skeletons in their enlarged, rounder, and lessangular skulls. AIrican and European skulls oI halI a million years agowere suIIiciently similar to skulls oI us moderns that they areclassiIied in our species, Homo sapiens, instead oI in Homo erectus.This distinction is necessarily arbitrary, since Homo erectus evolvedinto Homo sapiens. However, these early Homo sapiens still diIIeredIrom us in skeletal details, had brains signiIicantly smaller than ours,and were grossly diIIerent Irom us in their artiIacts and behavior.Modern stone-tool-making peoples, such as Yali's great-grandparents,would have scorned the stone tools oI halI a million years ago as verycrude. The only other signiIicant addition to our ancestors' culturalrepertoire that can be documented with conIidence around that timewas the use oI Iire. No art, bone tool, or anything else has come down to us Iromearly Homo sapiens except Ior their skeletal remains, plus those crudestone tools. There were still no humans in Australia, Ior the obviousreason that it would have taken boats to get there Irom SoutheastAsia. There were also no humans anywhere in the Americas, becausethat would have required the occupation oI the nearest part oI theEurasian continent (Siberia), and possibly boat-building skills as well.(The present, shallow Bering Strait, separating Siberia Irom Alaska,alternated between a strait and a broad intercontinental bridge oI dryland, as sea level repeatedly rose and Iell during the Ice Ages.)However, boat building and survival in cold Siberia were both still Iarbeyond the capabilities oI early Homo sapiens. AIter halI a million years ago, the human populations oI AIricaand western Eurasia proceeded to diverge Irom each other and IromEast Asian populations in skeletal details. The population oI Europeand western Asia between 130,000 and 40,000 years ago isrepresented by especially many skeletons, known as Neanderthals andsometimes classiIied as a separate species, Homo neanderthalensis.Despite being depicted in innumerable cartoons as apelike brutesliving in caves, Neanderthals had brains slightly larger than our own.They were also the Iirst humans to leave behind strong evidence oIburying their dead and caring Ior their sick. Yet their stone tools werestill crude by comparison with modern New Guineans' polished stoneaxes and were usually not yet made in standardized diverse shapes,each with a clearly recognizable Iunction. The Iew preserved AIrican skeletal Iragments contemporary withthe Neanderthals are more similar to our modern skeletons than toNeanderthal skeletons. Even Iewer preserved East Asian skeletalIragments are known, but they appear diIIerent again Irom bothAIricans and Neanderthals. As Ior the liIestyle at that time, the best-preserved evidence comes Irom stone artiIacts and prey bonesaccumulated at southern AIrican sites. Although those AIricans oI100,000 years ago had more modern skeletons than did theirNeanderthal contemporaries, they made essentially the same crudestone tools as Neanderthals, still lacking standardized shapes. Theyhad no preserved art. To judge Irom the bone evidence oI the animalspecies on which they preyed, their hunting skills were unimpressiveand mainly directed at easy-to-kill, not-at-all-dangerous animals. Theywere not yet in the business oI slaughtering buIIalo, pigs, and otherdangerous prey. They couldn't even catch Iish: their sites immediatelyon the seacoast lack Iish bones and Iishhooks. They and theirNeanderthal contemporaries still rank as less than Iully human. Human history at last took oII around 50,000 years ago, at thetime oI what I have termed our Great Leap Forward. The earliestdeIinite signs oI that leap come Irom East AIrican sites withstandardized stone tools and the Iirst preserved jewelry (ostrich-shellbeads). Similar developments soon appear in the Near East and insoutheastern Europe, then (some 40,000 years ago) in southwesternEurope, where abundant artiIacts are associated with Iully modernskeletons oI people termed Cro-Magnons. ThereaIter, the garbagepreserved at archaeological sites rapidly becomes more and moreinteresting and leaves no doubt that we are dealing with biologicallyand behaviorally modern humans. Cro-Magnon garbage heaps yield not only stone tools but alsotools oI bone, whose suitability Ior shaping (Ior instance, intoIishhooks) had apparently gone unrecognized by previous humans.Tools were produced in diverse and distinctive shapes so modern thattheir Iunctions as needles, awls, engraving tools, and so on areobvious to us. Instead oI only single-piece tools such as hand-heldscrapers, multipiece tools made their appearance. Recognizablemultipiece weapons at Cro-Magnon sites include harpoons, spear-throwers, and eventually bows and arrows, the precursors oI riIles andother multipiece modern weapons. Those eIIicient means oI killing ata saIe distance permitted the hunting oI such dangerous prey as rhinosand elephants, while the invention oI rope Ior nets, lines, and snaresallowed the addition oI Iish and birds to our diet. Remains oI housesand sewn clothing testiIy to a greatly improved ability to survive incold climates, and remains oI jewelry and careIully buried skeletonsindicate revolutionary aesthetic and spiritual developments. OI the Cro-Magnons' products that have been preserved, the bestknown are their artworks: their magniIicent cave paintings, statues,and musical instruments, which we still appreciate as art today.Anyone who has experienced Iirsthand the overwhelming power oIthe liIe-sized painted bulls and horses in the Lascaux Cave oIsouthwestern France will understand at once that their creators musthave been as modern in their minds as they were in their skeletons. Obviously, some momentous change took place in our ancestors'capabilities between about 100,000 and 50,000 years ago. That GreatLeap Forward poses two major unresolved questions, regarding itstriggering cause and its geographic location. As Ior its cause, I arguedin my book The Third Chimpan:ee Ior the perIection oI the voice boxand hence Ior the anatomical basis oI modern language, on which theexercise oI human creativity is so dependent. Others have suggestedinstead that a change in brain organization around that time, without achange in brain size, made modern language possible. As Ior the site oI the Great Leap Forward, did it take placeprimarily in one geographic area, in one group oI humans, who werethereby enabled to expand and replace the Iormer human populationsoI other parts oI the world? Or did it occur in parallel in diIIerentregions, in each oI which the human populations living there todaywould be descendants oI the populations living there beIore the leap?The rather modern-looking human skulls Irom AIrica around 100,000years ago have been taken to support the Iormer view, with the leapoccurring speciIically in AIrica. Molecular studies (oI so-calledmitochondrial DNA) were initially also interpreted in terms oI anAIrican origin oI modern humans, though the meaning oI thosemolecular Iindings is currently in doubt. On the other hand, skulls oIhumans living in China and Indonesia hundreds oI thousands oI yearsago are considered by some physical anthropologists to exhibitIeatures still Iound in modern Chinese and in Aboriginal Australians,respectively. II true, that Iinding would suggest parallel evolution andmultiregional origins oI modern humans, rather than origins in asingle Garden oI Eden. The issue remains unresolved. The evidence Ior a localized origin oI modern humans, Iollowedby their spread and then their replacement oI other types oI humanselsewhere, seems strongest Ior Europe. Some 40,000 years ago, intoEurope came the Cro-Magnons, with their modern skeletons, superiorweapons, and other advanced cultural traits. Within a Iew thousandyears there were no more Neanderthals, who had been evolving as thesole occupants oI Europe Ior hundreds oI thousands oI years. Thatsequence strongly suggests that the modern Cro-Magnons somehowused their Iar superior technology, and their language skills or brains,to inIect, kill, or displace the Neanderthals, leaving behind little or noevidence oI hybridization between Neanderthals and Cro-Magnons. The great leap Forward coincides with the Iirst proven majorextension oI human geographic range since our ancestors'colonization oI Eurasia. That extension consisted oI the occupation oIAustralia and New Guinea, joined at that time into a single continent.Many radiocarbondated sites attest to human presence inAustralia/New Guinea between 40,000 and 30,000 years ago (plus theinevitable somewhat older claims oI contested validity). Within ashort time oI that initial peopling, humans had expanded over thewhole continent and adapted to its diverse habitats, Irom the tropicalrain Iorests and high mountains oI New Guinea to the dry interior andwet southeastern corner oI Australia. During the Ice Ages, so much oI the oceans' water was locked upin glaciers that worldwide sea levels dropped hundreds oI Ieet belowtheir present stand. As a result, what are now the shallow seasbetween Asia and the Indonesian islands oI Sumatra, Borneo, Java,and Bali became dry land. (So did other shallow straits, such as theBering Strait and the English Channel.) The edge oI the SoutheastAsian mainland then lay 700 miles east oI its present location.Nevertheless, central Indonesian islands between Bali and Australiaremained surrounded and separated by deepwater channels. To reachAustralia/New Guinea Irom the Asian mainland at that time stillrequired crossing a minimum oI eight channels, the broadest oI whichwas at least 50 miles wide. Most oI those channels divided islandsvisible Irom each other, but Australia itselI was always invisible Iromeven the nearest Indonesian islands, Timor and Tanimbar. Thus, theoccupation oI Australia/New Guinea is momentous in that itdemanded watercraIt and provides by Iar the earliest evidence oI theiruse in history. Not until about 30,000 years later (13,000 years ago) isthere strong evidence oI watercraIt anywhere else in the world, Iromthe Mediterranean. Initially, archaeologists considered the possibility that thecolonization oI Australia/New Guinea was achieved accidentally byjust a Iew people swept to sea while Iishing on a raIt near anIndonesian island. In an extreme scenario the Iirst settlers are picturedas having consisted oI a single pregnant young woman carrying amale Ietus. But believers in the Iluke-colonization theory have beensurprised by recent discoveries that still other islands, lying to the eastoI New Guinea, were colonized soon aIter New Guinea itselI, byaround 35,000 years ago. Those islands were New Britain and NewIreland, in the Bismarck Archipelago, and Buka, in the SolomonArchipelago. Buka lies out oI sight oI the closest island to the westand could have been reached only by crossing a water gap oI about100 miles. Thus, early Australians and New Guineans were probablycapable oI intentionally traveling over water to visible islands, andwere using watercraIt suIIiciently oIten that the colonization oI eveninvisible distant islands was repeatedly achieved unintentionally. The settlement oI Australia/New Guinea was perhaps associatedwith still another big Iirst, besides humans' Iirst use oI watercraIt andIirst range extension since reaching Eurasia: the Iirst massextermination oI large animal species by humans. Today, we regardAIrica as the continent oI big mammals. Modern Eurasia also hasmany species oI big mammals (though not in the maniIest abundanceoI AIrica's Serengeti Plains), such as Asia's rhinos and elephants andtigers, and Europe's moose and bears and (until classical times) lions.Australia/New Guinea today has no equally large mammals, in Iact nomammal larger than 100-pound kangaroos. But Australia/New GuineaIormerly had its own suite oI diverse big mammals, including giantkangaroos, rhinolike marsupials called diprotodonts and reaching thesize oI a cow, and a marsupial "leopard." It also Iormerly had a 400-pound ostrichlike Ilightless bird, plus some impressively big reptiles,including a one-ton lizard, a giant python, and land-dwellingcrocodiles. All oI those Australian/New Guinean giants (the so-calledmegaIauna) disappeared aIter the arrival oI humans. While there hasbeen controversy about the exact timing oI their demise, severalAustralian archaeological sites, with dates extending over tens oIthousands oI years, and with prodigiously abundant deposits oI animalbones, have been careIully excavated and Iound to contain not a traceoI the now extinct giants over the last 35,000 years. Hence themegaIauna probably became extinct soon aIter humans reachedAustralia. The near-simultaneous disappearance oI so many large speciesraises an obvious question: what caused it? An obvious possibleanswer is that they were killed oII or else eliminated indirectly by theIirst arriving humans. Recall that Australian/New Guinean animalshad evolved Ior millions oI years in the absence oI human hunters.We know that Galapagos and Antarctic birds and mammals, whichsimilarly evolved in the absence oI humans and did not see humansuntil modern times, are still incurably tame today. They would havebeen exterminated iI conservationists had not imposed protectivemeasures quickly. On other recently discovered islands whereprotective measures did not go into eIIect quickly, exterminations didindeed result: one such victim, the dodo oI Mauritius, has becomevirtually a symbol Ior extinction. We also know now that, on everyone oI the well-studied oceanic islands colonized in the prehistoricera, human colonization led to an extinction spasm whose victimsincluded the moas oI New Zealand, the giant lemurs oI Madagascar,and the big Ilightless geese oI Hawaii. Just as modern humans walkedup to unaIraid dodos and island seals and killed them, prehistorichumans presumably walked up to unaIraid moas and giant lemurs andkilled them too. Hence one hypothesis Ior the demise oI Australia's and NewGuinea's giants is that they met the same Iate around 40,000 yearsago. In contrast, most big mammals oI AIrica and Eurasia survivedinto modern times, because they had coevolved with protohumans Iorhundreds oI thousands or millions oI years. They thereby enjoyedample time to evolve a Iear oI humans, as our ancestors' initially poorhunting skills slowly improved. The dodo, moas, and perhaps thegiants oI Australia/New Guinea had the misIortune suddenly to beconIronted, without any evolutionary preparation, by invading modernhumans possessing Iully developed hunting skills. However, the overkill hypothesis, as it is termed, has not goneunchallenged Ior Australia/New Guinea. Critics emphasize that, asyet, no one has documented the bones oI an extinct Australian/NewGuinean giant with compelling evidence oI its having been killed byhumans, or even oI its having lived in association with humans.DeIenders oI the overkill hypothesis reply: you would hardly expectto Iind kill sites iI the extermination was completed very quickly andlong ago, such as within a Iew millennia some 40,000 years ago. Thecritics respond with a countertheory: perhaps the giants succumbedinstead to a change in climate, such as a severe drought on the alreadychronically dry Australian continent. The debate goes on. Personally, I can't Iathom why Australia's giants should havesurvived innumerable droughts in their tens oI millions oI years oIAustralian history, and then have chosen to drop dead almostsimultaneously (at least on a time scale oI millions oI years) preciselyand just coincidentally when the Iirst humans arrived. The giantsbecame extinct not only in dry central Australia but also in drenchingwet New Guinea and southeastern Australia. They became extinct inevery habitat without exception, Irom deserts to cold rain Iorest andtropical rain Iorest. Hence it seems to me most likely that the giantswere indeed exterminated by humans, both directly (by being killedIor Iood) and indirectly (as the result oI Iires and habitat modiIicationcaused by humans). But regardless oI whether the overkill hypothesisor the climate hypothesis proves correct, the disappearance oI all oIthe big animals oI Australia/New Guinea had, as we shall see, heavyconsequences Ior subsequent human history. Those extinctionseliminated all the large wild animals that might otherwise have beencandidates Ior domestication, and leIt native Australians and NewGuineans with not a single native domestic animal. Thus, the colonization oI Australia/New Guinea was not achieveduntil around the time oI the Great Leap Forward. Another extension oIhuman range that soon Iollowed was the one into the coldest parts oIEurasia. While Neanderthals lived in glacial times and were adaptedto the cold, they penetrated no Iarther north than northern Germanyand Kiev. That's not surprising, since Neanderthals apparently lackedneedles, sewn clothing, warm houses, and other technology essentialto survival in the coldest climates. Anatomically modern peoples whodid possess such technology had expanded into Siberia by around20,000 years ago (there are the usual much older disputed claims).That expansion may have been responsible Ior the extinction oIEurasia's woolly mammoth and woolly rhinoceros. With the settlement oI Australia/New Guinea, humans nowoccupied three oI the Iive habitable continents. (Throughout thisbook, I count Eurasia as a single continent, and I omit Antarcticabecause it was not reached by humans until the 19th century and hasnever had any selI-supporting human population.) That leIt only twocontinents, North America and South America. They were surely thelast ones settled, Ior the obvious reason that reaching the AmericasIrom the Old World required either boats (Ior which there is noevidence even in Indonesia until 40,000 years ago and none in Europeuntil much later) in order to cross by sea, or else it required theoccupation oI Siberia (unoccupied until about 20,000 years ago) inorder to cross the Bering land bridge. However, it is uncertain when,between about 14,000 and 35,000 years ago, the Americas were Iirstcolonized. The oldest unquestioned human remains in the Americasare at sites in Alaska dated around 12,000 B.C., Iollowed by aproIusion oI sites in the United States south oI the Canadian borderand in Mexico in the centuries just beIore 11,000 B.C. The latter sitesare called Clovis sites, named aIter the type site near the town oIClovis, New Mexico, where their characteristic large stonespearpoints were Iirst recognized. Hundreds oI Clovis sites are nowknown, blanketing all 48 oI the lower U.S. states south into Mexico.Unquestioned evidence oI human presence appears soon thereaIter inAmazonia and in Patagonia. These Iacts suggest the interpretation thatClovis sites document the Americas' Iirst colonization by people, whoquickly multiplied, expanded, and Iilled the two continents. One might at Iirst be surprised that Clovis descendants couldreach Patagonia, lying 8,000 miles south oI the U.S.-Canada border,in less than a thousand years. However, that translates into an averageexpansion oI only 8 miles per year, a trivial Ieat Ior a hunter-gathererlikely to cover that distance even within a single day's normalIoraging. One might also at Iirst be surprised that the Americas evidentlyIilled up with humans so quickly that people were motivated to keepspreading south toward Patagonia. That population growth alsoproves unsurprising when one stops to consider the actual numbers. IIthe Americas eventually came to hold hunter-gatherers at an averagepopulation density oI somewhat under one person per square mile (ahigh value Ior modern hunter-gatherers), then the whole area oI theAmericas would eventually have held about 10 million hunter-gatherers. But even iI the initial colonists had consisted oI only 100people and their numbers had increased at a rate oI only 1.1 percentper year, the colonists' descendants would have reached thatpopulation ceiling oI 10 million people within a thousand years. Apopulation growth rate oI 1.1 percent per year is again trivial: rates ashigh as 3.4 percent per year have been observed in modern timeswhen people colonized virgin lands, such as when the HMS Bountymutineers and their Tahitian wives colonized Pitcairn Island. The proIusion oI Clovis hunters' sites within the Iirst Iewcenturies aIter their arrival resembles the site proIusion documentedarchaeologically Ior the more recent discovery oI New Zealand byancestral Maori. A proIusion oI early sites is also documented Ior themuch older colonization oI Europe by anatomically modern humans,and Ior the occupation oI Australia/New Guinea. That is, everythingabout the Clovis phenomenon and its spread through the Americascorresponds to Iindings Ior other, unquestioned virgin-landcolonizations in history. What might be the signiIicance oI Clovis sites' bursting Iorth inthe centuries just beIore 11,000 B.C., rather than in those beIore16,000 or 21,000 B.C.? Recall that Siberia has always been cold, andthat a continuous ice sheet stretched as an impassable barrier acrossthe whole width oI Canada during much oI the Pleistocene Ice Ages.We have already seen that the technology required Ior coping withextreme cold did not emerge until aIter anatomically modern humansinvaded Europe around 40,000 years ago, and that people did notcolonize Siberia until 20,000 years later. Eventually, those earlySiberians crossed to Alaska, either by sea across the Bering Strait(only 50 miles wide even today) or else on Ioot at glacial times whenBering Strait was dry land. The Bering land bridge, during itsmillennia oI intermittent existence, would have been up to a thousandmiles wide, covered by open tundra, and easily traversable by peopleadapted to cold conditions. The land bridge was Ilooded and becamea strait again most recently when sea level rose aIter around 14,000B.C. Whether those early Siberians walked or paddled to Alaska, theearliest secure evidence oI human presence in Alaska dates Iromaround 12,000 B.C. Soon thereaIter, a north-south ice-Iree corridor opened in theCanadian ice sheet, permitting the Iirst Alaskans to pass through andcome out into the Great Plains around the site oI the modern Canadiancity oI Edmonton. That removed the last serious barrier betweenAlaska and Patagonia Ior modern humans. The Edmonton pioneerswould have Iound the Great Plains teeming with game. They wouldhave thrived, increased in numbers, and gradually spread south tooccupy the whole hemisphere. One other Ieature oI the Clovis phenomenon Iits our expectationsIor the Iirst human presence south oI the Canadian ice sheet. LikeAustralia/New Guinea, the Americas had originally been Iull oI bigmammals. About 15,000 years ago, the American West looked muchas AIrica's Serengeti Plains do today, with herds oI elephants andhorses pursued by lions and cheetahs, and joined by members oI suchexotic species as camels and giant ground sloths. Just as inAustralia/New Guinea, in the Americas most oI those large mammalsbecame extinct. Whereas the extinctions took place probably beIore30,000 years ago in Australia, they occurred around 17,000 to 12,000years ago in the Americas. For those extinct American mammalswhose bones are available in greatest abundance and have been datedespecially accurately, one can pinpoint the extinctions as havingoccurred around 11,000 B.C. Perhaps the two most accurately datedextinctions are those oI the Shasta ground sloth and Harrington'smountain goat in the Grand Canyon area; both oI those populationsdisappeared within a century or two oI 11,100 B.C. Whethercoincidentally or not, that date is identical, within experimental error,to the date oI Clovis hunters' arrival in the Grand Canyon area. The discovery oI numerous skeletons oI mammoths with Clovisspearpoints between their ribs suggests that this agreement oI dates isnot a coincidence. Hunters expanding southward through theAmericas, encountering big animals that had never seen humansbeIore, may have Iound those American animals easy to kill and mayhave exterminated them. A countertheory is that America's bigmammals instead became extinct because oI climate changes at theend oI the last Ice Age, which (to conIuse the interpretation Iormodern paleontologists) also happened around 11,000 B.C. Personally, I have the same problem with a climatic theory oImegaIaunal extinction in the Americas as with such a theory inAustralia/New Guinea. The Americas' big animals had alreadysurvived the ends oI 22 previous Ice Ages. Why did most oI thempick the 23rd to expire in concert, in the presence oI all thosesupposedly harmless humans? Why did they disappear in all habitats,not only in habitats that contracted but also in ones that greatlyexpanded at the end oI the last Ice Age? Hence I suspect that Clovishunters did it, but the debate remains unresolved. Whichever theoryproves correct, most large wild mammal species that might otherwisehave later been domesticated by Native Americans were therebyremoved. Also unresolved is the question whether Clovis hunters reallywere the Iirst Americans. As always happens whenever anyone claimsthe Iirst anything, claims oI discoveries oI pre-Clovis human sites inthe Americas are constantly being advanced. Every year, a Iew oIthose new claims really do appear convincing and exciting wheninitially announced. Then the inevitable problems oI interpretationarise. Were the reported tools at the site really tools made by humans,or just natural rock shapes? Are the reported radiocarbon dates reallycorrect, and not invalidated by any oI the numerous diIIiculties thatcan plague radiocarbon dating? II the dates are correct, are they reallyassociated with human products, rather than just being a 15,000-year-old lump oI charcoal lying next to a stone tool actually made 9,000years ago? To illustrate these problems, consider the Iollowing typicalexample oI an oIten quoted pre-Clovis claim. At a Brazilian rockshelter named Pedro Furada, archaeologists Iound cave paintingsundoubtedly made by humans. They also discovered, among the pilesoI stones at the base oI a cliII, some stones whose shapes suggestedthe possibility oI their being crude tools. In addition, they came uponsupposed hearths, whose burnt charcoal yielded radiocarbon dates oIaround 35,000 years ago. Articles on Pedro Furada were accepted Iorpublication in the prestigious and highly selective internationalscientiIic journal Nature. But none oI those rocks at the base oI the cliII is an obviouslyhuman-made tool, as are Clovis points and Cro-Magnon tools. IIhundreds oI thousands oI rocks Iall Irom a high cliII over the courseoI tens oI thousands oI years, many oI them will become chipped andbroken when they hit the rocks below, and some will come toresemble crude tools chipped and broken by humans. In westernEurope and elsewhere in Amazonia, archaeologists have radiocarbon-dated the actual pigments used in cave paintings, but that was notdone at Pedro Furada. Forest Iires occur Irequently in the vicinity andproduce charcoal that is regularly swept into caves by wind andstreams. No evidence links the 35,000-year-old charcoal to theundoubted cave paintings at Pedro Furada. Although the originalexcavators remain convinced, a team oI archaeologists who were notinvolved in the excavation but receptive to pre-Clovis claims recentlyvisited the site and came away unconvinced. The North American site that currently enjoys the strongestcredentials as a possible pre-Clovis site is MeadowcroIt rock shelter,in Pennsylvania, yielding reported human-associated radiocarbondates oI about 16,000 years ago. At MeadowcroIt no archaeologistdenies that many human artiIacts do occur in many careIullyexcavated layers. But the oldest radiocarbon dates don't make sense,because the plant and animal species associated with them are speciesliving in Pennsylvania in recent times oI mild climates, rather thanspecies expected Ior the glacial times oI 16,000 years ago. Hence onehas to suspect that the charcoal samples dated Irom the oldest humanoccupation levels consist oI post-Clovis charcoal inIiltrated with oldercarbon. The strongest pre-Clovis candidate in South America is theMonte Verde site, in southern Chile, dated to at least 15,000 yearsago. It too now seems convincing to many archaeologists, but cautionis warranted in view oI all the previous disillusionments. II there really were pre-Clovis people in the Americas, why is itstill so hard to prove that they existed? Archaeologists have excavatedhundreds oI American sites unequivocally dating to between 2000 and11,000 B.C., including dozens oI Clovis sites in the North AmericanWest, rock shelters in the Appalachians, and sites in coastalCaliIornia. Below all the archaeological layers with undoubted humanpresence, at many oI those same sites, deeper older layers have beenexcavated and still yield undoubted remains oI animals--but with noIurther evidence oI humans. The weaknesses in pre-Clovis evidence inthe Americas contrast with the strength oI the evidence in Europe,where hundreds oI sites attest to the presence oI modern humans longbeIore Clovis hunters appeared in the Americas around 11,000 B.C.Even more striking is the evidence Irom Australia/New Guinea, wherethere are barely one-tenth as many archaeologists as in the UnitedStates alone, but where those Iew archaeologists have neverthelessdiscovered over a hundred unequivocal pre-Clovis sites scattered overthe whole continent. Early humans certainly didn't Ily by helicopter Irom Alaska toMeadowcroIt and Monte Verde, skipping all the landscape inbetween. Advocates oI pre-Clovis settlement suggest that, Iorthousands or even tens oI thousands oI years, pre-Clovis humansremained at low population densities or poorly visiblearchaeologically, Ior unknown reasons unprecedented elsewhere inthe world. I Iind that suggestion inIinitely more implausible than thesuggestion that Monte Verde and MeadowcroIt will eventually bereinterpreted, as have other claimed pre-Clovis sites. My Ieeling isthat, iI there really had been pre-Clovis settlement in the Americas, itwould have become obvious at many locations by now, and we wouldnot still be arguing. However, archaeologists remain divided on thesequestions. The consequences Ior our understanding oI later Americanprehistory remain the same, whichever interpretation proves correct.Either: the Americas were Iirst settled around 11,000 B.C. andquickly Iilled up with people. Or else: the Iirst settlement occurredsomewhat earlier (most advocates oI pre-Clovis settlement wouldsuggest by 15,000 or 20,000 years ago, possibly 30,000 years ago,and Iew would seriously claim earlier); but those pre-Clovis settlersremained Iew in numbers, or inconspicuous, or had little impact, untilaround 11,000 B.C. In either case, oI the Iive habitable continents,North America and South America are the ones with the shortesthuman prehistories. With the occupation oI the Americas, most habitable areas oI thecontinents and continental islands, plus oceanic islands IromIndonesia to east oI New Guinea, supported humans. The settlementoI the world's remaining islands was not completed until moderntimes: Mediterranean islands such as Crete, Cyprus, Corsica, andSardinia between about 8500 and 4000 B.C.; Caribbean islandsbeginning around 4000 B.C.; Polynesian and Micronesian islandsbetween 1200 B.C. and A.D. 1000; Madagascar sometime betweenA.D. 300 and 800; and Iceland in the ninth century A.D. NativeAmericans, possibly ancestral to the modern Inuit, spread throughoutthe High Arctic around 2000 B.C. That leIt, as the sole uninhabitedareas awaiting European explorers over the last 700 years, only themost remote islands oI the Atlantic and Indian Oceans (such as theAzores and Seychelles), plus Antarctica. What signiIicance, iI any, do the continents' diIIering dates oIsettlement have Ior subsequent history? Suppose that a time machinecould have transported an archaeologist back in time, Ior a world tourat around 11,000 B.C. Given the state oI the world then, could thearchaeologist have predicted the sequence in which human societieson the various continents would develop guns, germs, and steel, andthus predicted the state oI the world today? Our archaeologist might have considered the possible advantagesoI a head start. II that counted Ior anything, then AIrica enjoyed anenormous advantage: at least 5 million more years oI separateprotohuman existence than on any other continent. In addition, iI it istrue that modern humans arose in AIrica around 100,000 years agoand spread to other continents, that would have wiped out anyadvantages accumulated elsewhere in the meantime and givenAIricans a new head start. Furthermore, human genetic diversity ishighest in AIrica; perhaps more-diverse humans would collectivelyproduce more-diverse inventions. But our archaeologist might then reIlect: what, really, does a"head start" mean Ior the purposes oI this book? We cannot take themetaphor oI a Iootrace literally. II by head start you mean the timerequired to populate a continent aIter the arrival oI the Iirst Iewpioneering colonists, that time is relatively brieI: Ior example, lessthan 1,000 years to Iill up even the whole New World. II by head startyou instead mean the time required to adapt to local conditions, Igrant that some extreme environments did take time: Ior instance,9,000 years to occupy the High Arctic aIter the occupation oI the restoI North America. But people would have explored and adapted tomost other areas quickly, once modern human inventiveness haddeveloped. For example, aIter the ancestors oI the Maori reached NewZealand, it apparently took them barely a century to discover allworthwhile stone sources; only a Iew more centuries to kill every lastmoa in some oI the world's most rugged terrain; and only a Iewcenturies to diIIerentiate into a range oI diverse societies, Irom that oIcoastal hunter-gatherers to that oI Iarmers practicing new types oIIood storage. Our archaeologist might thereIore look at the Americas andconclude that AIricans, despite their apparently enormous head start,would have been overtaken by the earliest Americans within at most amillennium. ThereaIter, the Americas' greater area (50 percent greaterthan AIrica's) and much greater environmental diversity would havegiven the advantage to Native Americans over AIricans. The archaeologist might then turn to Eurasia and reason asIollows. Eurasia is the world's largest continent. It has been occupiedIor longer than any other continent except AIrica. AIrica's longoccupation beIore the colonization oI Eurasia a million years agomight have counted Ior nothing anyway, because protohumans were atsuch a primitive stage then. Our archaeologist might look at the UpperPaleolithic Ilowering oI southwestern Europe between 20,000 and12,000 years ago, with all those Iamous artworks and complex tools,and wonder whether Eurasia was already getting a head start then, atleast locally. Finally, the archaeologist would turn to Australia/New Guinea,noting Iirst its small area (it's the smallest continent), the largeIraction oI it covered by desert capable oI supporting Iew humans, thecontinent's isolation, and its later occupation than that oI AIrica andEurasia. All that might lead the archaeologist to predict slowdevelopment in Australia/New Guinea. But remember that Australians and New Guineans had by Iar theearliest watercraIt in the world. They were creating cave paintingsapparently at least as early as the Cro-Magnons in Europe. JonathanKingdon and Tim Flannery have noted that the colonization oIAustralia/New Guinea Irom the islands oI the Asian continental shelIrequired humans to learn to deal with the new environments theyencountered on the islands oI central Indonesia--a maze oI coastlinesoIIering the richest marine resources, coral reeIs, and mangroves inthe world. As the colonists crossed the straits separating eachIndonesian island Irom the next one to the east, they adapted anew,Iilled up that next island, and went on to colonize the next islandagain. It was a hitherto unprecedented golden age oI successivehuman population explosions. Perhaps those cycles oI colonization,adaptation, and population explosion were what selected Ior the GreatLeap Forward, which then diIIused back westward to Eurasia andAIrica. II this scenario is correct, then Australia/New Guinea gained amassive head start that might have continued to propel humandevelopment there long aIter the Great Leap Forward. Thus, an observer transported back in time to 11,000 B.C. couldnot have predicted on which continent human societies would developmost quickly, but could have made a strong case Ior any oI thecontinents. With hindsight, oI course, we know that Eurasia was theone. But it turns out that the actual reasons behind the more rapiddevelopment oI Eurasian societies were not at all the straightIorwardones that our imaginary archaeologist oI 11,000 B.C. guessed. Theremainder oI this book consists oI a quest to discover those realreasons. Footnote: Throughout this book, dates Ior about the last 15,000years will be quoted as so-called calibrated radiocarbon dates, ratherthan as conventional, uncalibrated radiocarbon dates. The diIIerencebetween the two types oI dates will be explained in Chapter 5.Calibrated dates are the ones believed to correspond more closely toactual calendar dates. Readers accustomed to uncalibrated dates willneed to bear this distinction in mind whenever they Iind me quotingapparently erroneous dates that are older than the ones with whichthey are Iamiliar. For example, the date oI the Clovis archaeologicalhorizon in North America is usually quoted as around 9000 B.C.(11,000 years ago), but I quote it instead as around 11,000 B.C.(13,000 years ago), because the date usually quoted is uncalibrated.P R O L O G U EYALI ' S QUESTI ONWE ALL KNOW THAT HISTORY HAS PROCEEDED VERY DIFIerentlyIor peoples Irom diIIerent parts oI the globe. In the 13,000 years since the endoI the last Ice Age, some parts oI the world developed literate industrialsocieties with metal tools, other parts developed only nonliterate Iarmingsocieties, and still others retained societies oI hunter-gatherers with stone tools.Those historical inequalities have cast long shadows on the modern world,because the literate societies with metal tools have conquered or exterminatedthe other societies. While those diIIerences constitute the most basic Iact oIworld history, the reasons Ior them remain uncertain and controversial. Thispuzzling question oI their origins was posed to me 25 years ago in a simple,personal Iorm.In July 1972 I was walking along a beach on the tropical island oI NewGuinea, where as a biologist I study bird evolution. I had already heard abouta remarkable local politician named Yali, who was touring the district then.By chance, Yali and I were walking in the same direction on that day, and heovertook me. We walked together Ior an hour, talking during the whole time.Yali radiated charisma and energy. His eyes Ilashed in a mesmerizingway. He talked conIidently about himselI, but he also asked lots oI probingquestions and listened intently. Our conversation began with a subject then14 ' P R O L O G U Eon every New Guinean's mindthe rapid pace oI politicaldevelopments. Papua New Guinea, as Yali's nation is now called, was atthat time still administered by Australia as a mandate oI the United'Nations,but independence was in the air. Yali explained to me his role in getting localpeople to prepare Ior selI-government.AIter a while, Yali turned the conversation and began to quiz me. Hehad never been outside New Guinea and had not been educated beyondhigh school, but his curiosity was insatiable. First, he wanted to knowabout my work on New Guinea birds (including how much I got paid Iorit). I explained to him how diIIerent groups oI birds had colonized NewGuinea over the course oI millions oI years. He then asked how the ancestorsoI his own people had reached New Guinea over the last tens oI thousands oIyears, and how white Europeans had colonized New Guinea within thelast 200 years.The conversation remained Iriendly, even though the tension betweenthe two societies that Yali and I represented was Iamiliar to both oI us.Two centuries ago, all New Guineans were still "living in the Stone Age."That is, they still used stone tools similar to those superseded in Europe bymetal tools thousands oI years ago, and they dwelt in villages not organizedunder any centralized political authority. Whites had arrived, imposedcentralized government, and brought material goods whose value NewGuineans instantly recognized, ranging Irom steel axes, matches, andmedicines to clothing, soIt drinks, and umbrellas. In New Guinea all thesegoods were reIerred to collectively as "cargo."Many oI the white colonialists openly despised New Guineans as"primitive." Even the least able oI New Guinea's white "masters," as theywere still called in 1972, enjoyed a Iar higher standard oI living than NewGuineans, higher even than charismatic politicians like Yali. Yet Yali hadquizzed lots oI whites as he was then quizzing me, and I had quizzed lots oINew Guineans. He and I both knew perIectly well that New Guineans areon the average at least as smart as Europeans. All those things must havebeen on Yali's mind when, with yet another penetrating glance oI hisIlashing eyes, he asked me, "Why is it that you white people developed somuch cargo and brought it to New Guinea, but we black people had littlecargo oI our own?"It was a simple question that went to the heart oI liIe as Yali experiencedit. Yes, there still is a huge diIIerence between the liIestyle oI the averageY A L T S QUES TI O N 15New Guinean and that oI the average European or American.Comparable diIIerences separate the liIestyles oI other peoples oI theworld as well. Those huge disparities must have potent causes that onemight think would be obvious.Yet Yali's apparently simple question is a diIIicult one to answer. I didn'thave an answer then. ProIessional historians still disagree about thesolution; most are no longer even asking the question. In the years sinceYali and I had that conversation, I have studied and written about otheraspects oI human evolution, history, and language. This book, writtentwenty-Iive years later, attempts to answer Yali.ALTHOUGH YALI'S QUESTI ON concerned only the contrasting liIestyles oINew Guineans and oI European whites, it can be extended to a larger setoI contrasts within the modern world. Peoples oI Eurasian origin,especially those still living in Europe and eastern Asia, plus thosetransplanted to North America, dominate the modern world in wealth andpower. Other peoples, including most AIricans, have thrown oII Europeancolonial domination but remain Iar behind in wealth and power. Still otherpeoples, such as the aboriginal inhabitants oI Australia, the Americas, andsouthernmost AIrica, are no longer even masters oI their own lands buthave been decimated, subjugated, and in some cases even exterminated byEuropean colonialists.Thus, questions about inequality in the modern world can bereIormulated as Iollows. Why did wealth and power become distributed asthey now are, rather than in some other way? For instance, why weren'tNative Americans, AIricans, and Aboriginal Australians the ones whodecimated, subjugated, or exterminated Europeans and Asians?We can easily push this question back one step. As oI the year A.D.1500, when Europe's worldwide colonial expansion was just beginning,peoples on diIIerent continents already diIIered greatly in technology andpolitical organization. Much oI Europe, Asia, and North AIrica was thesite oI metal-equipped states or empires, some oI them on the threshold oIindustrialization. Two Native American peoples, the Aztecs and the Incas,ruled over empires with stone tools. Parts oI sub-Saharan AIrica weredivided among small states or chieIdoms with iron tools. Most other peoplesincluding all those oI Australia and New Guinea, many PaciIicI 6 P R O L O G U Eislands, much oI the Americas, and small parts oI sub-Saharan AIrica lived as Iarming tribes or even still as hunter-gatherer bands using stonetools.OI course, those technological and political diIIerences as oI A.D. 1500were the immediate cause oI the modern world's inequalities. Empires withsteel weapons were able to conquer or exterminate tribes with weapons oIstone and wood. How, though, did the world get to be the way it was inA.D. 1500?Once again, we can easily push this question back one step Iurther, bydrawing on written histories and archaeological discoveries. Until the end oIthe last Ice Age, around 11,000 B.C., all peoples on all continents were stillhunter-gatherers. DiIIerent rates oI development on diIIerent continents,Irom 11,000 B.C. to A.D. 1500, were what led to the technological andpolitical inequalities oI A.D. 1500. While Aboriginal Australians and manyNative Americans remained hunter-gatherers, most oI Eurasia and much oIthe Americas and sub-Saharan AIrica gradually developed agriculture,herding, metallurgy, and complex political organization. Parts oI Eurasia,and one area oI the Americas, independently developed writing as well.However, each oI these new developments appeared earlier in Eurasiathan elsewhere. For instance, the mass production oI bronze tools, whichwas just beginning in the South American Andes in the centuries beIoreA.D. 1500, was already established in parts oI Eurasia over 4,000 yearsearlier. The stone technology oI the Tasmanians, when Iirst encountered byEuropean explorers in A.D. 1642, was simpler than that prevalent in parts oIUpper Paleolithic Europe tens oI thousands oI years earlier.Thus, we can Iinally rephrase the question about the modern world'sinequalities as Iollows: why did human development proceed at suchdiIIerent rates on diIIerent continents? Those disparate rates constitutehistory's broadest pattern and my book's subject.While this book is thus ultimately about history and prehistory, itssubject is not oI just academic interest but also oI overwhelming practicaland political importance. The history oI interactions among disparatepeoples is what shaped the modern world through conquest, epidemics, andgenocide. Those collisions created reverberations that have still not dieddown aIter many centuries, and that are actively continuing in some oIthe world's most troubled areas today.For example, much oI AIrica is still struggling with its legacies Iromrecent colonialism. In other regionsincluding much oI Central America,Y A L I ' S Q U E S T I O N 17Mexico, Peru, New Caledonia, the Iormer Soviet Union, and parts oIIndonesiacivil unrest or guerrilla warIare pits still-numerous indigenouspopulations against governments dominated by descendants oI invadingconquerors. Many other indigenous populationssuch as native Hawai-ians Aboriginal Australians, native Siberians, and Indians in the UnitedStates, Canada, Brazil, Argentina, and Chilebecame so reduced innumbers by genocide and disease that they are now greatly outnumberedby the descendants oI invaders. Although thus incapable oI mounting acivil war, they are nevertheless increasingly asserting their rights.In addition to these current political and economic reverberations oIpast collisions among peoples, there are current linguistic reverberationsespecially the impending disappearance oI most oI the modern world's6,000 surviving languages, becoming replaced by English, Chinese,Russian, and a Iew other languages whose numbers oI speakers haveincreased enormously in recent centuries. All these problems oI themodern world result Irom the diIIerent historical trajectories implicit inYali's question.BEFORE SEEKI NG ANSWERS to Yali's question, we should pause to considersome objections to discussing it at all. Some people take oIIense at the mereposing oI the question, Ior several reasons.One objection goes as Iollows. II we succeed in explaining how somepeople came to dominate other people, may this not seem to justiIy thedomination? Doesn't it seem to say that the outcome was inevitable, andthat it would thereIore be Iutile to try to change the outcome today? Thisobjection rests on a common tendency to conIuse an explanation oI causeswith a justiIication or acceptance oI results. What use one makes oI ahistorical explanation is a question separate Irom the explanation itselI.Understanding is more oIten used to try to alter an outcome than to repeat orperpetuate it. That's why psychologists try to understand the minds oImurderers and rapists, why social historians try to understand genocide,and why physicians try to understand the causes oI human disease. Thoseinvestigators do not seek to justiIy murder, rape, genocide, and illness.Instead, they seek to use their understanding oI a chain oI causes to interruptthe chain.Second, doesn't addressing Yali's question automatically involve aEurocentric approach to history, a gloriIication oI western Europeans, and anobsession with the prominence oI western Europe and EuropeanizedI 8 P R O L O G U EAmerica in the modern world? Isn't that prominence just anephemeral phenomenon oI the last Iew centuries, now Iading behind theprominence oI Japan and Southeast Asia? In Iact, most oI this book willdeal with peoples other than Europeans. Rather than Iocus solely oninteractions between Europeans and non-Europeans, we shall also examineinteractions between diIIerent non-European peoplesespecially those thattook place within sub-Saharan AIrica, Southeast Asia, Indonesia, andNew Guinea, among peoples native to those areas. Far Irom gloriIyingpeoples oI western European origin, we shall see that most basic elements oItheir civilization were developed by other peoples living elsewhere and werethen imported to western Europe.Third, don't words such as "civilization," and phrases such as "rise oIcivilization," convey the Ialse impression that civilization is good, tribalhunter-gatherers are miserable, and history Ior the past 13,000 years hasinvolved progress toward greater human happiness? In Iact, I do notassume that industrialized states are "better" than hunter-gatherer tribes, orthat the abandonment oI the hunter-gatherer liIestyle Ior iron-basedstatehood represents "progress," or that it has led to an increase in humanhappiness. My own impression, Irom having divided my liIe betweenUnited States cities and New Guinea villages, is that the so-called blessings oIcivilization are mixed. For example, compared with hunter-gatherers,citizens oI modern industrialized states enjoy better medical care, lower riskoI death by homicide, and a longer liIe span, but receive much less socialsupport Irom Iriendships and extended Iamilies. My motive Iorinvestigating these geographic diIIerences in human societies is not to celebrateone type oI society over another but simply to understand what happened inhistory.DOES YALI'S QUESTION really need another book to answer it? Don't wealready know the answer? II so, what is it?Probably the commonest explanation involves implicitly or explicitlyassuming biological diIIerences among peoples. In the centuries aIter A.D. 1500,as European explorers became aware oI the wide diIIerences among the world'speoples in technology and political organization, they assumed that thosediIIerences arose Irom diIIerences in innate ability. With the rise oI Darwiniantheory, explanations were recast in terms oI natural selection and oIevolutionary descent. Technologically primitive peoples were con-Y A L I ' S Q U E S T I O N 19sidered evolutionary vestiges oI human descent Irom apelikeancestors. The displacement oI such peoples by colonists Irom industrializedsocieties exempliIied the survival oI the Iittest. With the later rise oIgenetics, the explanations were recast once again, in genetic terms.Europeans became considered genetically more intelligent than AIricans, andespecially more so than Aboriginal Australians.Today, segments oI Western society publicly repudiate racism. Yet many(perhaps most!) Westerners continue to accept racist explanationsprivately or subconsciously. In Japan and many other countries, suchexplanations are still advanced publicly and without apology. Eveneducated white Americans, Europeans, and Australians, when the subject oIAustralian Aborigines comes up, assume that there is something primitiveabout the Aborigines themselves. They certainly look diIIerent Iromwhites. Many oI the living descendants oI those Aborigines who survivedthe era oI European colonization are now Iinding it diIIicult to succeedeconomically in white Australian society.A seemingly compelling argument goes as Iollows. White immigrants toAustralia built a literate, industrialized, politically centralized, democraticstate based on metal tools and on Iood production, all within a century oIcolonizing a continent where the Aborigines had been living as tribalhunter-gatherers without metal Ior at least 40,000 years. Here were twosuccessive experiments in human development, in which the environmentwas identical and the sole variable was the people occupying thatenvironment. What Iurther prooI could be wanted to establish that thediIIerences between Aboriginal Australian and European societies aroseIrom diIIerences between the peoples themselves?The objection to such racist explanations is not just that they areloathsome, but also that they are wrong. Sound evidence Ior the existenceoI human diIIerences in intelligence that parallel human diIIerences intechnology is lacking. In Iact, as I shall explain in a moment, modern"Stone Age" peoples are on the average probably more intelligent, not lessintelligent, than industrialized peoples. Paradoxical as it may sound, weshall see in Chapter 15 that white immigrants to Australia do not deservethe credit usually accorded to them Ior building a literate industrializedsociety with the other virtues mentioned above. In addition, peoples whountil recently were technologically primitivesuch as AboriginalAustralians and New Guineansroutinely master industrial technologieswhen given opportunities to do so.Z O PROLOGUEAn enormous eIIort by cognitive psychologists has gone into the searchIor diIIerences in IQ between peoples oI diIIerent geographic origins nowliving in the same country. In particular, numerous white Americanpsychologists have been trying Ior decades to demonstrate that blackAmericans oI AIrican origins are innately less intelligent than whiteAmericans oI European origins. However, as is well known, the peoplescompared diIIer greatly in their social environment and educationalopportunities. This Iact creates double diIIiculties Ior eIIorts to test thehypothesis that intellectual diIIerences underlie technological diIIerences.First, even our cognitive abilities as adults are heavily inIluenced by thesocial environment that we experienced during childhood, making it hard todiscern any inIluence oI preexisting genetic diIIerences. Second, tests oIcognitive ability (like IQ tests) tend to measure cultural learning and notpure innate intelligence, whatever that is. Because oI those undoubted eIIectsoI childhood environment and learned knowledge on IQ test results, thepsychologists' eIIorts to date have not succeeded in convincinglyestablishing the postulated genetic deIiciency in IQs oI nonwhite peoples.My perspective on this controversy comes Irom 33 years oI workingwith New Guineans in their own intact societies. From the very beginning oImy work with New Guineans, they impressed me as being on the averagemore intelligent, more alert, more expressive, and more interested in thingsand people around them than the average European or American is. Atsome tasks that one might reasonably suppose to reIlect aspects oI brainIunction, such as the ability to Iorm a mental map oI unIamiliarsurroundings, they appear considerably more adept than Westerners. OIcourse, New Guineans tend to perIorm poorly at tasks that Westernershave been trained to perIorm since childhood and that New Guineans havenot. Hence when unschooled New Guineans Irom remote villages visittowns, they look stupid to Westerners. Conversely, I am constantly aware oIhow stupid I look to New Guineans when I'm with them in the jungle,displaying my incompetence at simple tasks (such as Iollowing a jungletrail or erecting a shelter) at which New Guineans have been trained sincechildhood and I have not.It's easy to recognize two reasons why my impression that NewGuineans are smarter than Westerners may be correct. First, Europeans haveIor thousands oI years been living in densely populated societies withcentral governments, police, and judiciaries. In those societies, inIectiousepidemic diseases oI dense populations (such as smallpox) werehistorically theY A L I ' S Q U E S T I O N 21major cause oI death, while murders were relatively uncommon and astate oI war was the exception rather than the rule. Most Europeans whoescaped Iatal inIections also escaped other potential causes oI death andproceeded to pass on their genes. Today, most live-born Western inIantssurvive Iatal inIections as well and reproduce themselves, regardless oItheir intelligence and the genes they bear. In contrast, New Guineans havebeen living in societies where human numbers were too low Ior epidemicdiseases oI dense populations to evolve. Instead, traditional New GuineanssuIIered high mortality Irom murder, chronic tribal warIare, accidents,and problems in procuring Iood.Intelligent people are likelier than less intelligent ones to escape thosecauses oI high mortality in traditional New Guinea societies. However,the diIIerential mortality Irom epidemic diseases in traditional Europeansocieties had little to do with intelligence, and instead involved geneticresistance dependent on details oI body chemistry. For example, peoplewith blood group B or O have a greater resistance to smallpox than dopeople with blood group A. That is, natural selection promoting genes Iorintelligence has probably been Iar more ruthless in New Guinea than inmore densely populated, politically complex societies, where natural selectionIor body chemistry was instead more potent.Besides this genetic reason, there is also a second reason why NewGuineans may have come to be smarter than Westerners. ModernEuropean and American children spend much oI their time beingpassively entertained by television, radio, and movies. In the averageAmerican household, the TV set is on Ior seven hours per day. In contrast,traditional New Guinea children have virtually no such opportunities Iorpassive entertainment and instead spend almost all oI their waking hoursactively doing something, such as talking or playing with other children oradults. Almost all studies oI child development emphasize the role oIchildhood stimulation and activity in promoting mental development, andstress the irreversible mental stunting associated with reduced childhoodstimulation. This eIIect surely contributes a non-genetic component to thesuperior average mental Iunction displayed by New Guineans.That is, in mental ability New Guineans are probably geneticallysuperior to Westerners, and they surely are superior in escaping thedevastating developmental disadvantages under which most children inindustrialized societies now grow up. Certainly, there is no hint at all oI anyintellectual disadvantage oI New Guineans that could serve to answer Yali'squestion.IX P R O L O G U EThe same two genetic and childhood developmental Iactors are likelyto distinguish not only New Guineans Irom Westerners, but also hunter-gatherers and other members oI technologically primitive societies Irommembers oI technologically advanced societies in general. Thus, the usualracist assumption has to be turned on its head. Why is it that Europeans,despite their likely genetic disadvantage and (in modern times) theirundoubted developmental disadvantage, ended up with much more oI thecargo? Why did New Guineans wind up technologically primitive,despite what I believe to be their superior intelligence?A GENETIC EXPLANATION isn't the only possible answer to Yali's question.Another one, popular with inhabitants oI northern Europe, invokes thesupposed stimulatory eIIects oI their homeland's cold climate and theinhibitory eIIects oI hot, humid, tropical climates on human creativity andenergy. Perhaps the seasonally variable climate at high latitudes posesmore diverse challenges than does a seasonally constant tropical climate.Perhaps cold climates require one to be more technologically inventive tosurvive, because one must build a warm home and make warm clothing,whereas one can survive in the tropics with simpler housing and no clothing.Or the argument can be reversed to reach the same conclusion: the longwinters at high latitudes leave people with much time in which to sit indoorsand invent.Although Iormerly popular, this type oI explanation, too, Iails tosurvive scrutiny. As we shall see, the peoples oI northern Europe contributednothing oI Iundamental importance to Eurasian civilization until the lastthousand years; they simply had the good luck to live at a geographiclocation where they were likely to receive advances (such as agriculture,wheels, writing, and metallurgy) developed in warmer parts oI Eurasia. Inthe New World the cold regions at high latitude were even more oI ahuman backwater. The sole Native American societies to develop writingarose in Mexico south oI the Tropic oI Cancer; the oldest New Worldpottery comes Irom near the equator in tropical South America; and theNew World society generally considered the most advanced in art,astronomy, and other respects was the Classic Maya society oI the tropicalYucatan and Guatemala in the Iirst millennium A.D.Still a third type oI answer to Yali invokes the supposed importance oIlowland river valleys in dry climates, where highly productive agricultureY A L I ' S Q U E S T I O N Z 3depended on large-scale irrigation systems that in turn requiredcentralized bureaucracies. This explanation was suggested by the undoubtedIact that the earliest known empires and writing systems arose in the Tigrisand Euphrates Valleys oI the Fertile Crescent and in the Nile Valley oIEgypt. Water control systems also appear to have been associated withcentralized political organization in some other areas oI the world, includingthe Indus Valley oI the Indian subcontinent, the Yellow and YangtzeValleys oI China, the Maya lowlands oI Mesoamerica, and the coastal desertoI Peru.However, detailed archaeological studies have shown that complexirrigation systems did not accompanv the rise oI centralized bureaucracies butfollowed aIter a considerable lag. That is, political centralization arose Iorsome other reason and then permitted construction oI complex irrigationsystems. None oI the crucial developments preceding political centralizationin those same parts oI the world were associated with river valleys or withcomplex irrigation systems. For example, in the Fertile Crescent Ioodproduction and village liIe originated in hills and mountains, not in lowlandriver valleys. The Nile Valley remained a cultural backwater Ior about 3,000years aIter village Iood production began to Ilourish in the hills oI theFertile Crescent. River valleys oI the southwestern United States eventuallycame to support irrigation agriculture and complex societies, but only aItermany oI the developments on which those societies rested had beenimported Irom Mexico. The river valleys oI southeastern Australiaremained occupied by tribal societies without agriculture.Yet another type oI explanation lists the immediate Iactors that enabledEuropeans to kill or conquer other peoplesespecially European guns,inIectious diseases, steel tools, and manuIactured products. Such anexplanation is on the right track, as those Iactors demonstrably weredirectly responsible Ior European conquests. However, this hypothesis isincomplete, because it still oIIers only a proximate (Iirst-stage) explanationidentiIying immediate causes. It invites a search Ior ultimate causes: whywere Europeans, rather than AIricans or Native Americans, the ones to endup with guns, the nastiest germs, and steel?While some progress has been made in identiIying those ultimate causesin the case oI Europe's conquest oI the New World, AIrica remains a bigpuzzle. AIrica is the continent where protohumans evolved Ior the longesttime, where anatomically modern humans may also have arisen, andwhere native diseases like malaria and yellow Iever killed Europeanexplorers. II a long head start counts Ior anything, why didn't guns and2 4 ' P R O L O G U Esteel arise Iirst in AIrica, permitting AIricans and their germs toconquer Europe? And what accounts Ior the Iailure oI AboriginalAustralians to pass beyond the stage oI hunter-gatherers with stone tools?Questions that emerge Irom worldwide comparisons oI human societiesIormerly attracted much attention Irom historians and geographers. Thebest-known modern example oI such an eIIort was Arnold Toynbee's 12-volume Studv of Historv. Toynbee was especially interested in the internaldynamics oI 23 advanced civilizations, oI which 22 were literate and 19were Eurasian. He was less interested in prehistory and in simpler,nonliterate societies. Yet the roots oI inequality in the modern world lie Iarback in prehistory. Hence Toynbee did not pose Yali's question, nor did hecome to grips with what I see as history's broadest pattern. Otheravailable books on world history similarly tend to Iocus on advancedliterate Eurasian civilizations oI the last 5,000 years; they have a very brieItreatment oI pre-Columbian Native American civilizations, and an evenbrieIer discussion oI the rest oI the world except Ior its recent interactionswith Eurasian civilizations. Since Toynbee's attempt, worldwidesyntheses oI historical causation have Iallen into disIavor among mosthistorians, as posing an apparently intractable problem.Specialists Irom several disciplines have provided global syntheses oItheir subjects. Especially useIul contributions have been made by ecologicalgeographers, cultural anthropologists, biologists studying plant andanimal domestication, and scholars concerned with the impact oI inIectiousdiseases on history. These studies have called attention to parts oI thepuzzle, but they provide only pieces oI the needed broad synthesis that hasbeen missing.Thus, there is no generally accepted answer to Yali's question. On theone hand, the proximate explanations are clear: some peoples developedguns, germs, steel, and other Iactors conIerring political and economicpower beIore others did; and some peoples never developed these powerIactors at all. On the other hand, the ultimate explanationsIor example,why bronze tools appeared early in parts oI Eurasia, late and only locally inthe New World, and never in Aboriginal Australiaremain unclear.Our present lack oI such ultimate explanations leaves a big intellectualgap, since the broadest pattern oI history thus remains unexplained. Muchmore serious, though, is the moral gap leIt unIilled. It is perIectly obvious toeveryone, whether an overt racist or not, that diIIerent peoples haveIared diIIerently in history. The modern United States is a European-Y A L I ' S Q U E S T I O N 25molded society, occupying lands conquered Irom Native Americansand incorporating the descendants oI millions oI sub-Saharan blackAIricans brought to America as slaves. Modern Europe is not a societymolded by sub-Saharan black AIricans who brought millions oI NativeAmericans as slaves.These results are completely lopsided: it was not the case that 51percent oI the Americas, Australia, and AIrica was conquered by Europeans,while 49 percent oI Europe was conquered by Native Americans, AboriginalAustralians, or AIricans. The whole modern world has been shaped bylopsided outcomes. Hence they must have inexorable explanations, onesmore basic than mere details concerning who happened to win some battle ordevelop some invention on one occasion a Iew thousand years ago.It seems logical to suppose that history's pattern reIlects innatediIIerences among people themselves. OI course, we're taught that it's notpolite to say so in public. We read oI technical studies claiming todemonstrate inborn diIIerences, and we also read rebuttals claiming thatthose studies suIIer Irom technical Ilaws. We see in our daily lives that someoI the conquered peoples continue to Iorm an underclass, centuries aIterthe conquests or slave imports took place. We're told that this too is to beattributed not to any biological shortcomings but to social disadvantagesand limited opportunities.Nevertheless, we have to wonder. We keep seeing all those glaring,persistent diIIerences in peoples' status. We're assured that the seeminglytransparent biological explanation Ior the world's inequalities as oI A.D.1500 is wrong, but we're not told what the correct explanation is. Untilwe have some convincing, detailed, agreed-upon explanation Ior the broadpattern oI history, most people will continue to suspect that the racistbiological explanation is correct aIter all. That seems to me the strongestargument Ior writing this book.AUTHORS ARE REGULARLY asked by journalists to summarize a long book inone sentence. For this book, here is such a sentence: "History IolloweddiIIerent courses Ior diIIerent peoples because oI diIIerences amongpeoples' environments, not because oI biological diIIerences among peoplesthemselves."Naturally, the notion that environmental geography and biogeographyinIluenced societal development is an old idea. Nowadays, though, the2!"""""#""""""P R O L O G U Eview is not held in esteem by historians; it is considered wrong orsimplistic, or it is caricatured as environmental determinism anddismissed (ha as did Cambridge ProI oI history Martin Daunton!), or elsethe whole subject oI trying to understand worldwide diIIerences isshelved as too diIIicult. Yet geography obviously has some eIIect onhistory; the open question concerns how much eIIect, and whether geographycan account Ior history's broad pattern.The time is now ripe Ior a Iresh look at thes