Jared Diamond’s Just-So Story

The world history class I am TAing is reading Guns, Germs, and Steel which I have talked about briefly before. I decided to read along with the rest of the class as I haven’t read the full book (only the beginning and the end). I should note that the professor doesn’t necessarily agree or disagree with Diamond’s work – I have no clue how she regards this book, in fact – but she believes it easily provokes debate and will help students engage the material in a more critical way. I completely agree as this post shows.

Rereading the prologue I noticed a glaring evolutionary just-so story. As Jared Diamond considers himself an evolutionary biologist, how he allowed this argument to be in the book I do not understand. I did a brief search on Google and I didn’t see any comments on this particular problem – most focused on the much more important issues with his work.

So what’s the issue? Basically, no evidence, i.e., what usually constitutes a just-so story.

As you may or may not know, Diamond opens Guns, Germs, and Steel with a brief anecdote about how a native New Guinean named Yali asks him why are Westerners so wealthy and nations like New Guinea so poor? Diamond extrapolates Yali’s question: “Why did human development proceed at such different rates on different continents?” (16). He claims that “the commonest explanation involves implicitly or explicitly assuming biological differences among peoples” (18). Okay, maybe that is what people think, but he cites nothing here – something we will continue to see.

He says that while this is the commonest explanation, it is most certainly wrong – when it comes to intelligence anyway. According to Diamond, no differences in intelligence have been detected between races (20). Instead, IQ tests test cultural learning instead of some absolute value. (I have no idea if IQ is real or not but I know there is some debate but as I haven’t investigated the topic at all, I won’t comment here. I’ll just grant Diamond this assertion for the purposes of the post.)

After saying, “the [evil!!!] psychologists’ efforts to date have not succeeded in convincingly establishing the postulated genetic deficiency in IQs of nonwhite peoples” (20), he then says “my perspective on this controversy comes from 33 years of working with New Guineans in their own intact societies.”
Anecdotal evidence, here we come!

He notes how intelligence is relative – New Guineans would look stupid to us if they visited a major US city and had to navigate our bureaucracy (as an example) but US citizens would look stupid (and probably die) if we found ourselves in a rainforest. Okay.

Then: “It’s easy to recognize two reasons why my impression that New Guineans are smarter than Westerners may be correct” (20). He had alluded to this in the previous paragraph – he believes New Guineans are “on the average, more intelligent, more alert, more expressive, and more interested in things and people around them than the average European or American is.”

Again, he had just said there is no IQ difference between races, but now New Guineans are smarter.
What? Where is the evidence for this assertion? Unless he’s being incredibly nuanced here and I missed it, I think he just contradicted himself.

Now for the just-so story:

Diamond notes that “Europeans have for thousands of year been living in densely populated societies with central governments, police, and judiciaries. In those societies, infections epidemic diseases of dense populations (such as smallpox) were historically the major cause of death, while murders were relatively uncommon and a state of war was the exception rather than the rule” (21). In contrast, New Guineans didn’t suffer through as many major diseases but dealt with murder and war on a much more consistent basis. Diamond claims that because of these differing scenarios, Europeans have been selected for body chemistry (resistance to disease) and New Guineans have been selected for intelligence (as smart people are more likely to not be killed).


While this scenario might be possible, Diamond offers no evidence nor citations for any part of the story. It is instead built upon assumption upon assumption and forces the reader to actively search for sources relevant to this complex topic. Has there been selection for body chemistry or intelligence in these peoples? and Is intelligence and murder-escape correlation or causation? are just two questions I have and Diamond provides me with no sources as a starting point. I think that is inexcusable.

As an example of body chemistry selection, Diamond claims that people with O or B blood types have greater resistance to smallpox than people with blood type A. Again, Diamond provides no evidence for this assertion. Many sites also claim this resistance but offer no sources as well. I did find this review article that questions the assumption. So… no idea what’s true and Diamond has done nothing to help.

I want to know this though: if O confers some resistance to smallpox, why were Native Americans (who are almost exclusively O) so decimated by the disease when Europeans arrived? Anyone have an answer? How does Diamond take this into account? Possibly the O blood type didn’t spread until after smallpox – O was selected for because of smallpox. I quickly found this article, however, that says O was predominant before European contact. (I have no time to read it at the moment though).

Diamond moves on to another reason New Guineans are smarter than Westerners – we watch TV. In contrast, New Guineans have more active entertainment or things to get done in general which promotes mental development. Again, no evidence on how this applies to his argument.

“This effect [active engagement on that part of New Guineans] surely contributes a non-genetic component to the superior average mental function displayed by New Guineans” (21).

Diamond writes this sentence declaratively, unambiguously, and again, without citation.

Is Diamond right? Are New Guineans more intelligent than Westerners? I have no idea. They could be, they could not be, they could be the same. The problem I wanted to point out is not that Diamond is right or wrong, but that he provides no evidence for his argument. He actually cites the section about IQ – the Bell Curve by Herrnstein and Murray – and notes that it is “the best-known or most notorious entrant into the debate about group differences in intelligence” (444). No page numbers and I don’t even know how it applies to his argument. In fact, this isn’t really a citation at all, but “further reading.”

What is this? Unless I’m totally wrong, Jared Diamond has just put forth a scientific argument that isn’t scientific at all – a definitive just-so story. I even had to search for evidence of the blood type resistance claims myself. Yes, this is a book for a popular audience, but it is also for an academic audience and we should expect a more rigorous citation system when it comes to the authoritative statements Jared Diamond makes here.

Is this really a problem? I think so. Even though this story is only a few pages long, I think it hurts his overarching argument. He contradicts himself and then proposes some selection story without evidence – didn’t he read any SJ Gould? Diamond would have been better off just cutting the section, in my opinion.
Diamond’s just-so story is completely unnecessary and negatively affects how I I will view the rest of the book. Uncited generalizations abound with a lack of rigor and clear thought. I am sympathetic to Diamond’s goal – searching for ultimate causes to explain the the state of the world today rather than proximate causes – but my skepticism is now on guard (as it should be anyway).
Diamond, Jared. Guns, Germs, and Steel (1997).

10 thoughts on “Jared Diamond’s Just-So Story

  1. Sounds like VERY lazy writing. If I find out that my brother-in-law is taking that class, I’ll definitely tell him to check out what you have to say here.


  2. To be fair to Diamond, I don’t think he was claiming that what he wrote was the gospel truth. When I read GJ&S, I read that bit as a half-serious comment to the effect that if any human group has ‘evolved to be stupid’, it might well be Westerners.

    I think his point is that the debate over race & IQ tends to be between those who believe that white people are innately smart, vs those who deny there are any genetic differences.

    He’s pointing out that there’s no reason the debate has be limited to those two options.

    I agree with you that he offers no evidence for those points but I don’t think he’s asking you to believe it exactly. It’s more of a thought experiment.


    • You raise a good point – his thought experiment does offer a nice alternative to the normal dichotomous debate over IQ. However, I still believe his language implies that he does think it’s true to some extent by saying “my experience of 33 years” and his factual assertions. Like I said, he could be right or wrong but he doesn’t offer any citations to back himself up.

      My confusion is more or less why he even goes into the level of detail that he does. I think it would have been sufficient to say “I may be smart but I will die in the jungle if left alone” and leave it at that. The stuff with the blood types and just-so story just seem unnecessary.

      And even if it is just a thought experiment, why not include the citations anyway? Maybe someone (like me) will be interested in learning more about how selection has affected various peoples I know where to go for that topic but I suspect many would not.

      So while my language may have been a bit strong, I still feel that the lack of citations is inexcusable – it just doesn’t make sense to me to NOT throw some in.

      I appreciate the comment!


      • And no mention as to why evolutionary selection is a valid operator here. It seems that cultural habit would be the first place to look to explain any actual differences.


  3. There is probable inundation of the camp of dichotomously looking at IQ, but the fact remains that IQ predicts how far one will go in THIS world and THIS world is what people are living in. Many peoples have inherited and acquired wonderful (or horrible) traits. The key though, and this can’t be ignored, is that whatever has made the Europeans dominant, it is this type of “progress” (which is really facility for convenience, luxury, and scientific accomplishment which makes them far more powerful than any other, thereby acquiring the ability to protect said “easier living” or luxury) that EVERY OTHER HUMAN GROUP desires when they see it.

    Apart from that crucial point, Diamond seems to be arguing lamarckian type evolution. Perhaps at the current time (and smaller, different populations in close proximity to a special geography of the homeland) they appear more alert and “smart” while there are super lazy (would-be) smart people in America, but this only has to do with exercise, experience and the peril of survival. Put another way, I don’t need to slowly maneuver so as not to wake up the poisonous gaffigan or listen for the bubbling brook because …

    my ancestors figured out ways to not be annoyed by such things, download stuff off of satellites, and watch football with some beers before making transactions (or whatever you do, save lives using CT, etc.) tomorrow.


    • ” EVERY OTHER HUMAN GROUP desires when they see it.”

      The !kung san on why they are not agriculturalists, “why should we plant when there are so many mundungo nuts in the world” You really need to read guns, germs and steel before you criticize it. Diamond is not a lamarckian and this post is strictly about one story in a book, a story which is not even important to the book.


      • In fact, something consistently explored in ALL of Diamond’s books, but GGS especially, is that the sedentary specialization-driven rural/urban lifestyle (you associated it with Europeans but it developed independently almost everywhere, even areas absurdly poor in readily domesticable plants like sub-saharan Africa and the Mississippi Basin; and it was more universal in other areas which the idea of telic ‘progress’ tends to view poorly, like Iraq/Iran and China) is an absolutely horrible choice.

        If people, as you suggest, were motivated by Progress and Nice Things and so on to rationally choose their society’s modus vivendi, going from hunting-gathering to nomadic pastoralism or sedentary farming, or from nomadic pastoralism and sedentary farming to intensive agriculture, would be right out. Everyone’s health declines from a wider pool of diseases, and if you’re not lucky enough to be born into a desirable caste (which is present in a minority of HG societies, where almost everyone is related to someone important even in the largest such society and policy is reached via people more like aldermen than generalissimi), you have vanishingly little leisure time, a far worse caloric and nutritional diet, and far greater intrinsic vulnerability to crime and military intrusion. On a personal level, ‘civilization’ is bad for you, and it’s one of the major questions of prehistory why nomadic societies chose to settle down at all.

        Are we better off than contemporary nomads? Maybe. Were the Victorians or even the Edwardians? Almost certainly not. We are dragged into “civilization” kicking and screaming whether it’s from the slightly richer tribe down the river or the steam ship flying stereotyped carpets from every high place. Our societies are not. This is the central paradox behind the book.

        Incidentally, it’s not exactly true even that what you associate with “civilization” is what the Savages do. They are largely indifferent to our objects of veneration – politics, culture, morals – because they have their own that serve them perfectly well, and the exceptions don’t generally test the rule. (Who should be surprised that the US importing the Beatles didn’t result in a return to monarchy or even a national skiffle renaissance?) What they are interested in are our fine kitchenware, casual wear, and outdoors apparatus. They’re not yearning after a life in suburban America, they’re yearning after their own with nicer pruning hooks and machetes.

        Societies do evolve, but they don’t evolve in a direction. The telic process is one towards greater success, in whatever way you can define “success”, and defining it after your own surroundings or a utopian version of same is going to intrinsically produce absurdities, like dismissing the bacteria that make up most of the Earth’s biomass or the nomadic societies that dominate the history of the Earth up until the first millennium AD for their utter mutual inability to produce Paul Blart: Mall Cop.

        Also, on the original post, I think hammering a mostly popularizing book for using its preface to harass public misconceptions without copious citations is uncharitable at best and destructively ignorant or malicious at worst – what exactly would a citation about New Guineans flying airplanes prove that a reasonable person would have any reason to actually verify? That they exist? That central New Guinea does not, in fact, breed giant rats in the form of men? To the extent Diamond is working academically he functions academically, but the main thrust of the book and the vast majority of the words used are to advance a syncretic understanding of established research and fact rather than commit original scholarship.

        Begging for citations for informal anecdotes in the decade’s most significant science popularization work is not a scientific attitude but a Wikipedian one passing for it in travesty and it ill serves you as either a scientist or a reader of scientific work.


  4. The last paragraphs in pages 112-113 of Jared Diamond’s “Guns, Germs, and Steel” seem contradictory. The context begins in a laconic chapter 6 entitled “To Farm or Not to Farm?” (the only thing worse than Shakespeare is cheesy allusions to Shakespeare). If someone could read it over and let me know if I’m crazy that would be fantastic. Be well friends.


  5. Oh, gosh. Just so you know, IQ is, by definition, only the currently measured potential to do academic work. No one who created the tests ever said it meant more than that. High IQ will not get you so much as a bus ticket across town.
    Evolutionary biologists on the whole are conservative; not conservative politically as I suspect Jared Diamond is, but conservative in their conclusions. In general, the ones I studied with would not have drawn broad brush conclusions on flimsy and carefully selected evidence the way Dr Diamond did in this book. They in general would be suspicious of someone who found their own cultural background to be the most successful, found the most successful animals to be the ones they were familiar with as a child (sing old MacDonald’s Farm and you’ll see what I mean) and found the most successful political systems to be the ones that developed in the countries their ancestors came from. Dr Diamond is unabashed. Evolutionary biologists do not cite him.
    If you want to check out the Germs in Europe part of his thesis, read Armies of Pestilence: The Impact of Disease on History by Dr Bray; as a physician he is a Dr of the conditions he is writing about, and it knocks the socks off Dr Diamond, the geologist. Oh, and Dr Bray has citations. Then check out The Great Wave, by Dr Fischer; half of his book is citations and appendixes. That will settle your mind about the impact of wars in Europe. Then check out the impact of the Mongols in Asia, the middle East and Eastern Europe; there is a lot of data about the level of death and destruction in their wake; and any study of the genes of these areas will confirm the impact of war in these areas. Since that area controls half the population of the world it is hard to see them as unimportant.
    This all leaves the reasoning of Dr Diamond up in the air. His conclusions do not seem to follow his arguments in my mind.
    My private opinion is that the Western European system is successfully managing a great deal of the world economy right now because 1. their methods are hierarchical and thus power is concentrated in one place which leads to the ability for rapid change. 2. their technology has up to now trumped that of everyone else. 3. they have several beliefs that allow for totally vicious behavior. I believe that high production due to cows and wheat is an incidental epiphenomenon. But I am not writing a book about it. Dr Joanne Holland


    • “IQ is, by definition, only the currently measured potential to do academic work. No one who created the tests ever said it meant more than that.”

      And the potential to do academic work is not important – as if a society of all Masters and PhD with all other variables being equal doesn’t mean a whole lot? First of all, IQ is more than just that. At an individual level, a high IQ may measure the potential for academic work – sure. But on a societal level, it has demonstrated a strong correlation with economic and political success – and that is all the difference between more advanced and primitive nations today.

      You point on how a high IQ can’t get you a bus ticket is so moot and silly, I really have to question your seriousness. Of course, a high IQ can’t get you a bus ticket. But nobody cares about being third world country people being incapable of getting a bus ticket or doing menial tasks of any sort. Everyone can do that and there is no high development index country that is there based primarily on these things. What countries do differ in how much the general population is capable of doing abstract reasoning, math, philosophy, technology, and so on. That is what IQ explains. And that really is the DIFFERENTIATING variable.

      Then you talk about how Europe is doing better not because of IQ but because their technology is more advanced – but you fail to see the point and that is that Europe’s more advanced technology is explained by cognitive factors related to IQ. Again, you are not understanding the logical patterns here and you are ducking the main argument.

      Europe is not any more viscous than other continents. There is plenty of opportunity with free education, much more open immigration than the East, anti-racism laws, etc.


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