Guns, germs, and Steel: the fates of human societies

Norton & Co., New York, 1997

Guns, Germs, and Steel, my best-known book, was
published in 1997.  It has been translated into 36 languages, including all the major languages of book publishing, as well as languages of small markets such as Estonian and Serbian.  It won the 1998 Pulitzer Prize for General Non-fiction, plus numerous other prizes.  I shall now summarize Guns, Germs, and Steel’s question, its answer, extensions and discoveries since its publication, unresolved questions, and criticisms.


Guns, Germs, and Steel seek to answer the biggest question of post-Ice-Age human history: why Eurasian peoples, rather than peoples of other continents, became the ones to develop the ingredients of power (guns, germs, and steel) and to expand around the world.  An extraterrestrial being visiting the Earth 14,000 years ago could have been forgiven for failing to predict this outcome, because the human populations of other continents apparently also possessed advantages.  Africans enjoyed a huge head start, because Africa is the continent with by far the longest history of human occupation.  North America is a big fertile continent, with the result that it supports the richest and most productive nation today.  Australia provides by far the earliest evidence for human ability to cross wide water gaps, and some of the earliest widespread evidence for behaviorally modern humans.  Why, nevertheless, were Eurasians the ones to expand?

Although every lay person sees that this is a question crying out for answer, historians have mostly ignored this question.  Several reasons explain their neglect.  One reason is that the answer clearly lies in the pre-literate past, because by 3400 BC Eurasians (and North Africans, biogeographically and politically part of Eurasia rather than of sub-Saharan Africa) had already had metal tools for thousands of years and were starting to develop writing and empires, thousands of years before any of those things would appear on any other continent.   But most historians consider history to begin with the origins of writing, and consider the pre-literate past as lying outside the scope of their discipline and instead to be left to archaeologists.  Also, as we shall see, the answers to this question involve details of subjects (especially plant and animal biology and microbiology) in which history graduate students receive no training.  But lay people still want an answer to this obvious question.  As a result of the failure of historians to supply an answer, lay people often fall back on the transparent interpretation of supposed racial superiority of Eurasian people themselves, despite the lack of evidence for that interpretation.


My own interest in this question became rekindled by my experiences in New Guinea over the last 50 years.  When I arrived in New Guinea for the first time, it became clear to me almost immediately that New Guineans are curious, questioning, talkative people with complex languages and social relationships, on the average at least as intelligent as Europeans and Americans.  In New Guinea I’m the dope who can’t do elementary things like follow an unmarked trail or light a fire in the rain.  My New Guinea friends are patient with my shortcomings and don’t expect much of me when it comes to the everyday challenges of New Guinea life.  Why did I nevertheless come to New Guinea as a representative of the “advanced” colonizing society possessing steel tools and writing, when my New Guinea friends traditionally had only stone tools and no writing, 46,000 years after their ancestors had reached New Guinea?  Eventually, a New Guinean named Yali, in the course of a long conversation with me about birds and volcanoes and my work and other things, asked me the question directly: “Why is it that you white people developed so much cargo [i.e., steel tools and other products of civilization] and brought it to New Guinea, but we black people had little cargo of our own?”  Despite the obviousness of Yali’s question, I didn’t know how to answer him.  It took me 25 years until I was ready to offer an answer, in Guns, Germs, and Steel.

Traditional warfare: Dani tribesmen fighting with spears in the Baliem Valley of the New Guinea Highlands.  The highest one-day death toll in those wars occurred on June 4, 1966, when northern Dani killed face-to-face 125 southern Dani, many of whom the attackers would personally have known (or known of).  The death toll constituted 5% of the southerners’ population.  Photo credit: Karl G. Heider.

The answer depends on a synthesis of four bodies of information, in the fields of social science, botany, zoology, and microbiology, applied to findings of archaeology, linguistics, and human genetics.  Many social scientists have studied the development of complex societies around the world, and the emergence of technology, writing, centralized government, economic specialization, and social stratification.  The conclusion of social scientists is that all of these developments required sedentary populous societies producing storable food surpluses capable of feeding not only the food producers themselves, but also capable of feeding full-time political leaders, merchants, scribes, and technology specialists.  Until 11,000 years ago, all people everywhere on Earth were hunter/gatherers, living at modest population densities because the hunter/gatherer lifestyle yields only modest food quantities and little or no storable food surpluses.  (Some hunter/gatherers in especially productive environments became semi-sedentary and developed chiefs, but no hunter/gatherers went as far as developing kings, metal tools, or writing).  Beginning 11,000 years ago, it was the rise of food production (agriculture and herding), yielding 100 to 1,000 times more food per acre than the hunter/gatherer lifestyle, that fueled the rise of sedentary populous societies with storable food surpluses and all of their consequences.  That’s the first step in answering Yali’s question.

One might still wonder: if food production had arisen simultaneously all around the world, then peoples everywhere would have developed complex societies simultaneously, and the subsequent world dominance of Eurasian societies would remain unexplained.  Here, the bodies of information in the fields of botany and zoology become relevant.  Food production didn’t arise simultaneously around the world: in most of the world it never arose independently at all; it did arise independently in just nine small regions, from which it diffused to other regions; and, among those nine regions, it arose more than 10,000 years ago in the Fertile Crescent and possibly in China, but only as recently as 2500 BC in the eastern United States.  The value of the domesticated plants and animals also varied among regions: the  most numerous and productive suites of domesticated species arose in the Fertile Crescent, followed by China, Mexico, and the Andes, while the least numerous and least productive suites arose in the eastern U.S., New Guinea, and Ethiopia.

Why did food production arise in only nine regions?  Why were those regions not the most fertile and productive regions of modern agriculture, such as California, Europe, Japan, and Java?  Why didn’t ancient hunter/gatherers everywhere domesticate locally available wild species? – e.g., why didn’t Aboriginal Australians domesticate kangaroos, and why didn’t California Indians domesticate the oak trees on whose acorns they subsisted?  A century of research by botanists and zoologists has established that only certain plant and animal species lend themselves to domestication, and has identified the specific problems preventing the domestication of

Image from The World Until Yesterday.  Photo credit: Marka/SuperStock.

kangaroos, oak trees, and most other species.  This issue presented one of the crucial problems for me in writing Guns, Germs, and Steel.  It’s not enough to observe that kangaroos weren’t domesticated, and to conclude from that observation that kangaroos couldn’t be domesticated; that reasoning would be circular.  Hence I devoted two of the longest chapters of Guns, Germs, and Steel to assembling many independent lines of evidence showing that the explanation for the non-origins of domestication in most regions of the world, and the non-domestication of most wild species, lay with the wild plant and animal species themselves, not with the people of those regions.

The spread of food production from those nine centers of origin followed a striking geographic pattern: rapid spread along east/west axes (such as the axis of Eurasia), slower spread along north/south axes (such as those of the Americas and of Africa).  That’s because crop and livestock species, and people using technologies and social behaviors associated with those species, can spread more rapidly at the same latitude, where they always encounter constant day length and seasonality and similar diseases, than across bands of latitude, where they must adapt to different day lengths and seasonality and diseases.  My listeners and readers find this pattern as fascinating as did I: after I give a lecture on Guns, Germs, and Steel, I can often recognize those people nearby who have just come out of my lecture, because they are tracing horizontal and vertical lines in the air as they talk to each other.

Thus, one can explain as follows the reasons why the people who spread around the world were Eurasians, not Aboriginal Australians or Native Americans or sub-Saharan Africans.  The reasons had nothing to do with differences in the peoples themselves.  Instead, the reasons were continental differences in the available wild plant and animal species suitable for domestication, resulting in earlier domestication of a more productive suite of domesticates in Eurasia, plus Eurasia’s east/west axis that facilitated the spread of those domesticates throughout Eurasia.  That long sentence is what I answer when journalists ask me to summarize my 518-page book and 25 years of research in just one sentence for their busy readers.  That sentence also explains why Guns, Germs, and Steel, a book about the biggest pattern of human history, contains seven chapters about plant and animal domestication, plus four chapters about domestication’s consequences, but only five chapters about history itself; and why Guns, Germs, and Steel wasn’t written by a historian, but by a biogeographer.

Microbiology, the fourth of the four bodies of information necessary for answering Yali’s question, played a specific role in the Eurasian expansion.  One means by which Europeans were able to spread at the expense of other peoples was by infecting them (usually unintentionally) with epidemic infectious diseases such as smallpox and measles, to which Europeans had evolved some genetic resistance and had acquired much immune (antibody-based) resistance through historical and lifetime exposure respectively, while unexposed non-European peoples had no such exposure, hence no such resistance.  But why didn’t non-European peoples evolve deadly diseases of their own to give back to invading Europeans?  The explanation lies in microbiological studies of recent decades, which I summarized in one chapter of Guns, Germs, and Steel, and which Nathan Wolfe, Claire Panosian, and I updated in a 2007 paper posted on this website.  The exchange of major epidemic infectious diseases was one-sided, because most of those diseases in the temperate zones came to us humans from diseases of our domestic animals (such as cattle, pigs, and chickens) with which our ancestors lived in close contact after those animal species had been domesticated.  But of the world’s 14 species of valuable domestic mammals, 13 were Eurasian, only one American, and none Australian.  Hence Eurasians ended up as disease bearers, and with much resistance themselves to their own diseases.


Since I published Guns, Germs, and Steel in 1997, much new information has accumulated, which has enriched our understanding without fundamentally changing interpretations.  I discussed some of these extensions in new English-language editions of Guns, Germs, and Steel released in 2003 and 2007. 

Japan.  The two most important geographic areas that did not receive detailed separate coverage in the 1997 edition of Guns, Germs, and Steel were Japan and the Indian subcontinent.  The 2007 edition added a chapter on Japanese geography and pre-history, agriculture’s spread to Japan, and its consequences.

Origins of food production.  A recent series of excellent papers on plant and animal domestication was published in the Journal of Anthropological Research (volume 68, no. 2, 2012).  This series includes evidence that the Indian subcontinent should be considered an additional minor center of independent agricultural origins.  Other updates are my article “Evolution, consequences and the future of plant and animal domestication” (Nature 418: 34-41 (2002)) and Peter Bellwood’s book First Farmers: the Origins of Agricultural Societies (Oxford: Blackwell, 2005). 

Spreads of language families.  Updates include my paper with Peter Bellwood, “Farmers and their languages: the first expansions,” posted on this website; Peter Bellwood’s above-cited book First Farmers; and a book edited by Peter Bellwood and Colin Renfrew Examining the Language/Farming Dispersal Hypothesis (Cambridge, UK: McDonald Institute for Archaeological Research, 2002).  Much new information has emerged about the farming-related spread of the Austronesian and Indo-European language families and the Bantu sub-sub-sub family.  Edward Vajda made the surprising discovery of the first well-attested relationship between an Old World language family and a New World language family, when he demonstrated a relationship between the Na-Dene family of North America and the Yeniseian family of Central Siberia (The Dene-Yeniseian Connection (Anthropological Papers of the University of Alaska, N.S. vol. 5, nos. 1-2, 2010)).  This implies a long-distance ancient spread by hunter/gatherers in the absence of farming, as is also true for the spread of the Pama-Nyungan language family of Aboriginal Australia.

Spreads along east/west axes.  My evidence in Guns, Germs, and Steel for preferential spread along east/west rather than north/south axes was anecdotal; I did not do systematic surveys.  Two studies have now demonstrated this phenomenon quantitatively and systematically: Peter Turchin’s et al. (J. World-Syst, Res. XII: 219-229 (2006)), for the spread of political power; and a paper on the spread of languages, by David Laitin et al. (Proc. Nat. Acad. Sci. USA 109: 10263-10268 (2012)).

Extensions to economics.  Since 1997, some economists have extended the reasoning of Guns, Germs, and Steel to understanding a central question of historical economics: why are some nations rich while others are poor?  Ola Olsson and Douglas Hibbs showed that an early start towards farming and then to state formation explains much of the variation among national wealth today.  Valerie Bockstette, Areendan Chanda, and Louis Putterman “States and markets: the advantage of an early start” (Journal Economic Growth 7: 351-373 (2002)) showed that, if one compares nations that have still been poor in modern times, an early start towards farming and state formation helps explain the rate at which those poor nations are catching up in wealth today.

Extensions to the world of business.  From conversations with Bill Gates, Bill Lewis of McKinsey Global Institute, and others in the business world, I learned of possible parallels between the histories of societies as discussed in Guns, Germs, and Steel, and the histories of national business sectors, industrial belts, and individual companies.  Delicious examples include the contrasts in productivity between Germany’s beer industry and its metal industry, or between Japan’s food-processing industry and its consumer electronics industry.  The Afterword to my 2003 edition of Guns, Germs, and Steel discusses these and other equally delicious examples.

Modern trade: a professional store-keeper, selling manufactured goods to anyone who enters the store, in return for the government’s money.  Photo credit: Blend Images/PunchStock.

Adoption of Guns, Germs, and Steel in schools.  When I published Guns, Germs, and Steel, I wasn’t surprised at its adoption in college courses, but I didn’t expect it to be adopted in high schools and middle schools.  It therefore did surprise me when my twin sons, then in the 7th grade at middle school, came home from school one day angry at me, because the history teacher had assigned Guns, Germs, and Steel to their class and had invited me to visit the class for a discussion.  My sons hadn’t yet read Guns, Germs, and Steel, but they told me that, even without reading it, they knew that it was a bad book, and that they would horribly embarrassed to have to sit and squirm in class while their equally disgusted friends and classmates listened to me discuss the book.  When I arrived and stood up in front of the class, my sons were seated in the back row, with grim expressions on their faces.  As I began talking, their classmates showed more and more visible interest, and my sons gradually faced forwards, relaxed their disgusted body posture, and began smiling.  For me, that was the first of dozens of encounters with middle school and high school students reading Guns, Germs, and Steel.  Nowadays, virtually every time that I give a public lecture, there is at least one school class in attendance, and the students are invariably among my most enthusiastic listeners.


Differences within EurasiaGuns, Germs, and Steel is about differences of human societies between the different continents over the last 11,000 years.  Those differences are largely due to differences in the wild plant and animal species available for domestication, and in the continental axes.  The question arises: at how small a geographic scale, and on how short a time scale, are those factors still important?  They surely don’t explain the divergence between North and South Korea within the last 65 years.  In practice, the most important such question at an intermediate scale is the question: why, within Eurasia, were European societies, rather than the societies of China, the Indian subcontinent, or the Near East (the Fertile Crescent), the ones to expand?  Although that question is not the subject of Guns, Germs, and Steel, I knew that I couldn’t ignore that question entirely, and so I discussed it briefly in the Epilogue to the 1997 edition, and again in the Afterword to the 2003 edition.  Numerous interesting recent books have been written on this subject, of which a recent one is Ian Morris Why the West Rules – For Now (New York: Farrar, Straus and Giroux, 2010).  We are still not close to agreement on the answers.  Interpretations fall into two categories: a majority view invoking proximate causes of the last few centuries; and a minority view (including my view discussed in 1997 and 2003) invoking ultimate causes rooted in geography. 

Advantages of Eurasian species.  Eurasia was home to the largest number of valuable domesticable wild plant and animal species.  Why was that the case? 

A naïve answer would be: that’s just because Eurasia is the largest continent, and because species diversity is (all other things being equal) higher on large land masses than on small land masses.  But that naïve answer proves to be either wrong or else incomplete.  Tropical areas are more species-rich than are temperate areas, and most of Eurasia’s area lies in the temperate zones.  In at least the two groups of plants and animals most important to humans, something about Eurasia besides its area causes it to harbor a disproportionate number of the world’s valuable domesticable species.

One of those two cases is understood: the case of large-seeded wild grasses (cereals) such as wheat and barley, which contribute more calories to human diets than any other plants.  The geographer Mark Blumler tabulated the native distributions of the world’s 56 grasses with the largest seeds (summarized in Table 8.1 on page 140 of Guns, Germs, and Steel).  Of those 56, almost all are native to Mediterranean zones or other seasonally dry environments, and 32 are concentrated in the Mediterranean zone of Western Eurasia.  The world’s four other Mediterranean zones – those of Chile, California, South Africa, and Southwest Australia – offer respectively only 2, 1, 1, and 0 large-seeded wild grasses.  Half of the reason is that a Mediterranean climate of mild wet winters and long hot dry summers selects for large seeds of annual plants able to survive the long dry season, and to grow rapidly and outcompete smaller seeds when the rains return.  The other half of the reason is that, among the world’s Mediterranean zones, that of Western Eurasia is by far the largest, the one with the greatest range of altitudes and topographies within a short distance, the one with the greatest variation in climate between seasons and between years – hence the one that evolved the largest number of large-seeded wild grasses.  It’s possible that the same reasoning might apply to large-seeded wild legumes such as beans, but no one has done the corresponding calculations for legumes that Mark Blumler performed for grasses.

The other case is not understood.  Of the world’s 14 species of valuable large domesticated mammals, 13 are native to Eurasia, while only one (South America’s llama) is native to another region.  It’s true that Eurasia is home to more wild species of terrestrial herbivores or omnivorous mammals (72 species) than the next richest continent, Africa with 51 species.  Those wild species are the potential “candidates” for domestication.  But a much higher percentage of those candidate species were actually domesticable in Eurasia (18%) than in the other continents (0% for sub-Saharan Africa and Australia, 4% for the Americas), so Eurasia ended up with more domesticated species (Table 9.2 on page 162 of Guns, Germs, and Steel).  Why did so few of the big mammals for which Africa is famous proved domesticable?  It turns out that the domesticable large Eurasian species have a follow-the-leader herd structure based on a dominance hierarchy.  Hence it’s feasible for us humans to maintain the species in captivity in herds, to take over that hierarchy, and to drive the herds.  In contrast, all of Africa’s social antelope species are territorial in the breeding season, when they fight and don’t tolerate each other and can’t be herded.  What is it that selects for herds based on dominance hierarchies in Eurasia, and for territorial breeding behavior in sub-Saharan Africa?  We don’t know the answer.  It’s a question of zoology rather than of human sociology, but it’s a question that had important consequences for human history.

Questions about the failure to domesticate particular species. In many cases we can point to the factors, discussed in Guns, Germs, and Steel, that made it feasible to domesticate certain wild species (such as wheat and sheep), and impossible to domesticate others despite their importance and value to hunter/gatherers as food sources (such as oak trees and gazelles).  However, there remain cases that are often mentioned by my readers and listeners, and that puzzle them, as they do me.  The most frequently raised questions concern the non-domestication of zebras and of bison.

Of the eight species of wild equids (horses and their relatives) that survived until recent times, two were successfully domesticated (horse and donkey); the onager was commonly hunted in antiquity, but it is uncertain whether it was ever tamed and kept in captivity; and the other five (Africa’s three zebra species, the South African quagga, and the kiang of Tibet) were not domesticated.  Why were zebras not domesticated, despite their apparently being so similar to horses, able to interbreed with horses and donkeys, and locally abundant?  Suggested answers include: nasty disposition (by biting and kicking, captive zebras kill or cripple more American zoo-keepers than do captive tigers); keen peripheral vision that makes them impossible to lasso; and anatomy of the back that makes it difficult for them to support a rider’s weight.  Zebra-lovers object that there are some gentle captive zebras, and that zebras have occasionally been hitched to carts and (rarely) borne riders.  The fact remains that, even when Europeans experienced with livestock reach South Africa, they did experiment with zebras but abandoned them, suggesting that there really are obstacles to domesticating zebras.

The next most often-discussed non-domestication is that of bison.  Neither European nor American bison (probably conspecific rather than separate species) were domesticated, despite American bison being the dominant wild ungulate and most important game species of the North American plains and being successfully ranched today, and despite five other species of wild cattle having been domesticated (the aurochs ancestral to cows, the mithan, the banteng, the yak, and the water buffalo).  When I ask American readers and animal handlers familiar with bison the possible reasons for bison non-domestication, they mention two factors: unpredictable dangerous disposition, such that bison ranchers remain wary of them; and ability to jump fences, such they could not be penned until modern strong high fences became available.  One may object to citing claims of nasty disposition as a reason for non-domestication of bison and zebras, by noting that wild horses are, and the now-extinct aurochs was, also nasty and dangerous.  One may also object that some wild species have had nastiness successfully bred out of them by domestication, notably wolves and silver foxes.  However, one should not overgeneralize those successes by assuming that, because behavioral obstacles to domestication have been successfully bred out of a few wild animal species, they could be bred out of any wild animal species.  The fact remains that bison have not been domesticated in either North America or Europe despite long co-existence with human livestock handlers, and that suggests obstacles.

Criticisms and alternative views.  Guns, Germs, and Steel asks why human history unfolded differently on the different continents over the course of the last 11,000 years.  The book answers this question in two stages.  The first stage involves continental differences in the antiquity and productivity of food production and food storage, resulting from continental differences in wild plant and animal species available for domestication, and in continental axes.  That stage in turn rests on a huge body of studies by botanists and zoologists.  The second stage involves the political, social, economic, and technological developments in human societies caused by those differences in food production and in food storage.  That stage rests on a huge body of studies by archaeologists, cultural anthropologists, and other social scientists.

There is no serious, detailed alternative theory to explain why human history unfolded differently on the different continents.  There has been no refutation of the body of studies by botanists and zoologists about food production, nor of the body of studies by social scientists about food production’s consequences.

Nevertheless, Guns, Germs, and Steel has been criticized from three directions.  None of those criticisms constitutes an attempt to refute the book’s reasoning.  The criticisms instead involve people disliking the book’s interpretation or question, and expressing their generalized dislike.

One of the criticisms consists of using the term “geographic determinism” as a pejorative.  This term is invoked by some scholars in many contexts, in order to deny arguments that geographic factors contribute importantly to explanations of some human phenomena and dominate explanations of other human phenomena.  Elsewhere on this website, I have discussed what is wrong with this reflex response of “geographic determinism” to deny geographic explanations.

A second criticism comes from many people of European and Japanese ancestry, who believe that the long-term differences between human societies on different continents are instead due to genetic differences in IQ between different human populations.  Specifically, supporters of this view believe that Europeans or Japanese are on the average innately more intelligent than other peoples, and that’s why they were the first to develop guns, steel, and the other ingredients of modern power.  I have never heard proponents of this view discuss why IQ led to germs, a major driver of European conquests, also arising preferentially in Europe.  Proponents of this view also don’t discuss the bodies of research by botanists, zoologists, and social scientists underlying the interpretations of Guns, Germs, and Steel.

Proponents of this view recognize that their view is often viewed as “politically incorrect,” so I have encountered it much more often expressed privately in conversation than in writing.  Among the many accomplished and influential people who have expounded this view to me are numerous famous academics (especially in fields other than the social sciences), famous inventors, and powerful cabinet ministers. 

One problem with the view is that there is no convincing evidence for higher IQ, and for stronger genetic factors contributing to IQ, among people of European and Japanese ancestry, despite much effort devoted to obtaining such evidence.  It has proved difficult to develop cross-culturally valid methods of measuring IQ, and to separate genetic from learned contributions to IQ.  Another problem is that the view’s proponents focus on the IQ’s of modern Europeans and Japanese.  However, history’s broad pattern discussed in Guns, Germs, and Steel was already mostly in place by 3400 BC, by which time peoples of the Fertile Crescent had developed empires, writing, metal tools, and highly productive agriculture thousands of years before those ingredients of power arose elsewhere.  In fact, in most parts of the world, including Europe and Japan, those ingredients of power never arose independently at all: they were imported from the Fertile Crescent and from China via Korea respectively.  Hence IQ-based explanations should not focus on modern Europeans and Japanese, but instead on descendants of Fertile Crescent inhabitants of 3400 BC, such as modern Iraqis and Syrians.  So far as I know, proponents of the IQ hypothesis haven’t claimed that modern Iraqis and Syrians are innately superior to modern Europeans and other peoples in intelligence.

The remaining criticism comes especially from some politically liberal social scientists.  A pejorative term that they often invoke to tarnish Guns, Germs, and Steel is “Eurocentrism” i.e. focusing on Europe.  Racism and sexism are also sometimes mentioned or implied as criticisms.  One often cited example is a paper by the geographer Blout “Eight Eurocentric historians” [including me].  Explicitly or implicitly, the critics believe that discussions of Europe’s rise to power ought to be condemned as Eurocentric.  However, it’s a fact of history that Europe did rise to power, and that fact deserves explanation.  Guns, Germs, and Steel actually says little specifically about Europe but says a lot about the Fertile Crescent.  As for the charge of racism, Guns, Germs, and Steel’s conclusion is that history’s broad pattern has nothing to do with human racial characteristics and everything to do with plant and animal biology, so that the vast majority of readers see Guns, Germs, and Steel as refuting rather than promoting racist explanations.  As for the implication of sexism, Guns, Germs, and Steel contains scarcely any discussion of gender roles, not because they are unimportant in general, but because I know of no evidence that continental differences in gender roles contributed to the continental differences in societal development.

For these reasons, my current view, and that of many (most?) scholars who have seriously studied the question posed by Guns, Germs, and Steel, is that the book’s interpretation is correct, fundamentally and in detail.