Hypothesis, recent, Science

Origins and Exploration—An Interview with Dr. Lewis Dartnell

Dr. Lewis Dartnell is an award-winning research scientist in the field of astrobiology. In his most recent book, the Sunday Times bestseller Origins: How the Earth Made Us, Dartnell tells the story of how cosmic and geological forces have directed the evolution of humans and their civilizations. The following is an interview with Dr. Dartnell about Origins, as well as his field of expertise, astrobiology—the search for life in the universe.

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Logan Chipkin: Early in Origins, you describe a fascinating hypothesis which causally links the cosmic movements of Earth with the evolution of human intelligence. What is this hypothesis, in detail?

Lewis Dartnell: One of the big questions in evolutionary biology is: what drove our evolution from tree-swinging apes to bipedal, highly intelligent homonins that went on to build civilization and inherit the world? Primarily, what needs to happen is that the land around you needs to dry out, the forests need to be replaced by grasslands, by savannah. And what was driving that process over 5–6 million years since we diverged from the chimpanzee lineage was that East Africa dried out, because it was being pushed upwards. So the Ethiopian highlands were rising, probably because a magma plume beneath the crust of the planet was rising up in the interior. That also drove this splitting of the crust itself in a characteristic Y-shaped fracture, with two of those arms being the Red Sea and the Gulf of Aden, which then flooded in with the sea. And the third arm is the Great East African Rift Valley, which serves to block the moisture-rich air from either the ocean or from the rainforest in the interior of Africa from blowing over to East Africa until it’s dried out. So, what should be rainforest in East Africa has now dried out and is savannah, is grassland.

But the bigger question, what’s been puzzling paleontologists for a while, is what was it specifically about the Rift Valley in East Africa that created us as such an exquisitely intelligent species of ape. And the answer that’s been emerging over recent years is that the particular landscape of the Rift Valley—where the contrast between high mountainous ridges that shoulder either side of the Rift and the very low valley floor which is very hot and dry—means that there are lakes in that Rift Valley that are very sensitive to the precise balance between precipitation and evaporation, i.e., how much rain there is and how quickly it evaporates back away again. And that tectonic landscape interacts with what’s known as the Milankovitch cycle—these cosmic cycles of Earth’s orbit or its tilt, which cause slight variations in the amount of rain that the tropics experience.

So there is this whole set, this string of lakes on the Rift Valley floor, that in certain periods of time flicker rapidly in and out like loose light bulbs (they’ve been called “amplifier lakes”). This creates an unstable, rapidly fluctuating climate. The idea is that in this rapidly changing environment, we had to evolve intelligence to be able to survive.

LC: You argue that the “aimless wandering of the continents into their current configuration” indirectly “gave the civilizations of Eurasia a great developmental advantage through history.” How did Earth’s geography at the dawn of civilization advantage Eurasian civilizations and disadvantage those outside Eurasia?

LD: This is similar to the stuff that Jared Diamond had covered in Guns, Germs, and Steel, although he was looking specifically at Eurasia versus the Americas. And there are other arguments as to why Africa never developed civilization that became dominant in the way that European civilizations did. Ditto with Australasia. But regarding just Eurasia and the Americas— when the supercontinent Pangea broke up during the last great supercontinent cycle, it just so happened that one big chunk of it that became Eurasia was a huge, east-west oriented landmass. On the other hand, the Americas were ripped off by different tectonic faulting processes, and so they were pulled away into a predominantly north-south orientated continent.

And one of the main differences that that gives you for agricultural civilizations is that it is relatively easy to move domesticated crop species along the same line of latitude, i.e., east-west, because you have generally the same seasonality, length of day, that sort of thing, which is important to plants. So that meant that across Eurasia, things like cotton, rice, or wheat could be moved relatively easily between all civilizations across the continent, whereas in the Americas, which is north-south, it was much harder and slower to move crops around. One of the reasons why American societies were biologically disadvantaged is that it was harder for them to move their crops between different locations.

There’s another quirk of that distinction between Eurasia and the Americas, which is that the Americas were impoverished in the selection of large mammal species that could be domesticated, whereas Eurasia had a lot more. And part of the reason for that is that the first humans to migrate to the Americas across the Bering land bridge probably triggered a mega fauna extinction, which is something I talk about in the book. So there are both plant- and animal-related reasons why the Americas were biologically held back, and this is a broad brushstroke, grand theme of history.

LC: I did think of Guns, Germs, and Steel when reading your book.

LD: Yeah, I was delighted when some of the newspaper reviews in the U.K. compared Origins to Guns, Germs, and Steel and also to Sapiens, by Yuval Noah Harari. While Guns, Germs, and Steel was a great book, it only looked at a few of these deep causal links, and what I wanted to explore in Origins was that I thought there were more links in these chains of causation that could be used to explore the whole of human history.

LC: I don’t recall reading about the causal link between Earth’s cosmic cycles and human evolution in Guns, Germs, and Steel. That idea seems pretty new.

LD: Yeah, and there’s a lot of stuff that hasn’t really been talked about, such as the influence of the oceans’ dynamics on the Age of Exploration, and on building these transcontinental trade routes, which was the beginning of globalization.

LC: You write a lot in Origins about the friction between settled civilizations and nomadic peoples throughout history. How were two dramatically different lifestyles adopted in the same species, and why did they sometimes violently clash?

LD: This comes down to one of the fundamental contrasts within the Eurasian landmass. You have these different climate bands that are layered from the equator to the poles of planet Earth, and the important one for this part of the story is what is essentially the temperate climate band, where it is mild, moist, and rainy enough that you can support agriculture to grow enough food for agrarian societies, and therefore cities, and therefore settled civilizations built on growing crops in the ground.

Further to the north, you have a great stripe of a climate band across the very backbone of Eurasia, which are the steppes, the grasslands of Eurasia. And these are much more arid, which means that you cannot effectively grow enough food for yourself by using agriculture, but they do support very well an alternative mode of life, which is nomadic pastoralism, i.e., herding huge numbers of goat, sheep, or cattle. They eat the grass, which humans cannot eat themselves, and therefore humans are essentially using those herbivorous animals almost like processing machines to turn inedible grass into meat and milk that humans can digest.

Eurasian Steppe Belt (wikicommons)

This all leads to two fundamentally different and antagonistic lifestyles. And so throughout Eurasian history, going back to the Bronze age through to the 1700s, periodically and probably pressured by regional climate change within the steppes, the nomadic horse-riding peoples are driven out of their homeland to raid or invade the settled civilizations around the rim of Eurasia. This is very familiar from classical history, such as when the Huns appeared out of the steppes and triggered the collapse of the Western Roman Empire. It happened again with the Mongols, thundering out of the steppes and building the largest land empire that the world has ever seen by unifying the lands across the steppes. Throughout history, the Chinese had been repeatedly harassed by people they had called barbarians—horse riders coming out of the steppes. When you look at it in this light of planetary science interacting with history, the Great Wall of China is not just a defensive barrier, but it effectively follows this boundary, this line between two different ecological systems—between the temperate zone where you can grow crops, and the steppes where you have to be nomadic and herd sheep and ride horses.

LC: In Origins, you explain the emergence of different societal organizations as a result of particular ecological circumstances. Are you arguing for a kind of ecological determinism, such that the great civilizations were always going to emerge where they did on Earth, and not elsewhere?

LD: I think one needs to be very careful to hint or imply things like geographical determinism. Historically, arguments within geographical determinism have been used as excuses or to justify territorial expansionism, or racism and colonialism, or slavery. So the idea that one people is intrinsically or naturally linked to one part of the world, to a particular territory, to a particular location, is not what I’m talking about. Nor am I saying that some peoples are inherently better, or brighter, or advance more quickly, than others.

What I am saying is that you don’t want to throw the baby out with the bathwater. Undeniably, there is a deep link between physical, geographical features of the planet, or the atmosphere, or the ocean, and what opportunities or challenges that those have given people through the ages. And so some of the things we’ve been talking about, such as the climate bands of Eurasia, those would be there even if you rewound history back to 100,000 BC and pushed the play button again. Those physical features of the planet would be the same, and they would therefore have a similar driver or influence or effect on the subsequent development of, in this example, nomadic societies or settled civilizations. The pattern of winds around the world, driven by atmospheric circulation and dynamics, they would be exactly the same, so you would be able to have trade routes along similar lines, simply because of the physics of the atmosphere. So if you look in broad enough brushstrokes, both in terms of historical time and planetary scale, you can be fairly confident in your predictions about how such geographical features would affect the human story. But you can’t start predicting particular things, such as whether a particular war, or a particular leader came about because of geographical features.

LC: Your answer sounds like an argument against genetic determinism.

LD: The genetics across the entire human race are basically identical. As I point out in the book, there is more genetic diversity between two troops of monkeys on opposite sides of a river in Central Africa than there is in the 6 billion people living across the world outside of Africa. So in that sense, it’s not genetics that caused Eurasian civilizations to become technologically more advanced than American civilizations in the early 1500s. We are the same people, the same species. It was more these geological and geographical influences that were important.

LC: Astrobiology is the quest to understand the origin, evolution, distribution, and future of life in the Universe. Since you’ve begun your research career as an astrobiologist, in which of these subfields have we made the most progress, and what have we learned in that subfield?

LD: Astrobiology is a very interdisciplinary science. I came from a biology background, but I have friends that come from geology, planetary science, chemistry, astronomy, engineering, and so on. Astrobiology really is the thin sliver of overlap right in the middle of a huge Venn diagram of different disciplines. Over the last 15–20 years, we’ve been making huge advances in basically all of those fields. And so you might pick out things like extremophiles and our realization that life on Earth is in fact incredibly adaptable and tolerant of a huge range of different hostile environments, and therefore places like Mars are habitable in that sense. Or we’ve been discovering solar systems beyond our own star, our own Sun, and we are finding more and more Earth-like extrasolar planets, so there have been huge advances in that field as well. Or in our capabilities with robotics and instrumentation and exploring planets like Mars by sending our robotic emissaries, our robotic explorers to do what humans are not able to do just yet.

So there have been big advances in those areas as well as in many others within astrobiology that have been giving us increasing optimism that we are on the verge of discovering life on other planets if it’s there. It very well could be our generation that makes that profound discovery.

LC: What has recent research taught us about what features we expect life to have, should we discover it elsewhere?

LD: Within astrobiology, you try to base your expectations, your experiments, and your instruments on what is already known. So we base these on what we know of terrestrial biology and what sort of chemistries can enable something as complicated and complex as even a single-celled organism. But you also don’t want to be blinkered—you want to keep an open mind about how life could be different from our example. If life is extraterrestrial and alien, then by definition it could be different from us. So you’re trying to play off those two poles. When we go looking for life on Mars, for example, we’re not looking for a particular molecule—we’re not looking for DNA itself. We would look for complex organic chemistry in general, the sort of chemistry that you would not expect to have arisen in the absence of life, molecules that would not have been synthesized by geochemistry or by astrochemistry, but only by biochemistry—by the organization and direction that an organism can muster.

So in broad brushstrokes, we look for organic-based chemistry, carbon-based chemistry, and water-based life, although possibly on somewhere like Titan (one of Saturn’s moons), we should relax the assumption that life would be water-based. There, it might be methane-based or ammonia-based, there might be other solvents for life—other wet stuff that biochemistry and cells could be built on, but probably using carbon chemistry. Life, wherever you find it, will probably be organic (based on carbon compounds).

Lewis Dartnell (Pic: Aitken Jolly)

LC: Do you expect there to be an information code wherever we find life?

LD: Life seemingly has three core features. The first is that it should have some kind of complicated chemical network to extract energy from the environment and to synthesize the building blocks, the Lego bricks, of new cells, so life needs some kind of biochemistry, some kind of metabolic network. It would also need some kind of information storage retrieval and transmission system. We use DNA for that, for our genetics. And then it would need some kind of membrane, some kind of bag or sack around the cell, to simply delineate itself from the environment, so it can control its internal conditions. Those are three things that all cells on Earth have, and you can therefore start making expectations about what chemistry or molecules those three things might be built out of. But life is a process, life is a function, not an object, if you think about it that way.

LC: What is the shadow biosphere, and what could it tell us about the possibility for life in the Universe?

LD: We know that all life we’ve discovered so far on Earth is related. We can all be put as twigs onto the same huge evolutionary tree. And at the root of that, there is a progenitor—a last universal common ancestor (LUCA). But the fact that all life we’ve discovered on Earth can be traced to the same LUCA does not mean that life only evolved once on Earth. It just means that we are all the survivors of the same origin. And it stands to reason that if the conditions on Earth were appropriate for chemistry to become biochemistry to become life, then that wouldn’t have happened at just one location. It would’ve happened at several locations. And perhaps it’s not true that our form of life outcompeted all other forms.

Perhaps there are locations on Earth where we were not able to colonize as effectively, where the descendants of some other origin of life on Earth remain even today. Perhaps in extreme environments where our form of biochemistry falls apart, so maybe at very high temperatures, maybe in the depths of a hydrothermal vents, maybe deep in the Earth’s crust. These are the sort of places where we might expect to find what has come to be known as a shadow biosphere—life that is in some sense alien, even though it was born and lives on the same planet that we do. It would nevertheless be life that is based on a fundamentally different biochemistry because it came from a different origin event, a different genesis. The problem with that, though, is, how would you find something which is different from what you are familiar with? So in that sense, it’s a similar problem to that of looking for life on Mars—we’re looking for other Earthlings but with a very different biochemistry on our own planet.

And maybe there’s not just one shadow biosphere, maybe there are many. But you start having difficulties explaining how that situation would be stable. You would expect, even if there are different biochemistries, for one to start outcompeting the others, in the same way that if you have many species living in the same niche on earth, they start outcompeting each other, and only one prevails. So there might be one other shadow biosphere, but it’s hard to understand how lots of different shadow biospheres would be a stable system and not have outcompeted each other.

LC: What recent steps have scientists taken to look for life in our solar system and beyond?

LD: We’re designing probes to launch to Mars, and next year, 2020, both NASA and ESA (the European Space Agency) are sending their own rovers to look for signs of life on Mars, and that’s NASA’s Mars 2020 and ESA’s ExoMars rover. ExoMars is particularly interesting, because it will have a two-meter long drill onboard, so it will be able to get underground on Mars, and then pull handfuls of Martian dirt back up the surface. It’ll then be analyzed for signs of organic molecules and hopefully even biosignatures—signs of life itself, whether it’s extinct or not.

And there are plans on the drawing board for missions out to Europa (one of Jupiter’s moons), which is considered to be another habitable zone, another potential site of extraterrestrial life in our solar system. And then with the extrasolar planets outside our solar system and across the galaxy as a whole, we’re building steadily more capable space telescopes and ground-based observatories that not only detect that a planet is there, but actually could characterize that planet for us. And so we would start looking for planets in what is known as the habitable zone, or the Goldilocks zone, around the star. We would then start analyzing the light from the planet and start looking for the telltale fingerprint of gases like oxygen and methane, which, in combination, would be a very indicative biosignature, strongly suggesting that there is life, and specifically photosynthetic life, on that Earth-like planet.

LC: What are the most exciting astrobiology research projects in the near future?

LD: I’m very excited about next year’s space missions on ExoMars and Mars 2020, which I’ve mentioned. It would be good to look into the future a bit more with ESA’s JUICE mission (the Jupiter Icy moons Explorer), which would hopefully give us more information about Europa, which could lead to the construction of a dedicated Europa probe. So, if you’re looking towards the horizon, those are the most exciting upcoming space missions.


Dr. Lewis Dartnell is a research scientist, presenter, and author based in London, UK. His research is in the field of astrobiology and the search for microbial life on Mars. You can learn more about Lewis Dartnell and his research at his website and you can follow him on Twitter @lewis_dartnell

Logan Chipkin is a freelance writer and PhD candidate studying evolutionary theory, with a BA in physics from the University of Pennsylvania. His writing focuses on science, philosophy, economics, and culture. You can follow him on Twitter @ChipkinLogan

Photo by Aaron Thomas on Unsplash


  1. Andreas K. says

    I enjoy prehistoric anthropology of the kind this interview references. Indeed, one of the most curious things that I have found in Prehistory and History alike is that, whenever survival is possible, if left to their own devices, humans always seem to create a society which, though seldom equitable or egalitarian, inevitably, inexplicably, infuriatingly works and works very well so long as the conditions requiring it continue. A utilitarian drive is in a lot of what we do, apparently.

    However, since this interview also mentions origins, I’m going to add this observation, with a smile. You can’t help but notice how so many theories about the spread of early humans and the displacement of proto-human populations mention genetic indicators of interbreeding. You know, implying children, healthy, fertile children like when two perfectly human humans mate.

    I’m certainly no expert, but sometimes you almost suspect that evolutionary timelines beyond certain broad outlines are just the DnD campaigns of biologists who put all their skill points in Genetics, and spec’d Intelligence without saving any for Wisdom.

  2. Asenath Waite says

    I didn’t realize Justin Theroux was an astrobiologist.

  3. Farris says

    “And there are other arguments as to why Africa never developed civilization that became dominant in the way that European civilizations did.”

    North Africa ie. The Egyptians?

    According to Mr. Dartnell the rapidly changing climate of the Rift Valley presents challenges that requires an expansion of intelligence in order to survive.
    Yet the challenges imposed by a North/South continental rift verses and East/West causes the America’s populations to be stunted in comparison.
    Does increased intelligence correlate with additional survival challenges or an ease of survival?

    • RP says

      The theory is that survival challenge in a variable environment drives intelligence at the genetic level. (There’s some evidence of this in birds.) When the environment is changing rapidly genetics can’t evolve quickly enough so the species needs a layer of adaption capability that operates much more quickly ie. in the span of a single generation. Intelligence gives us greater ability to learn, relearn, and pass on knowledge and thereby adapt rapidly to a changing environment. Ultimately ‘adapting to survive in a variable environment’ equates with ‘evolving to learn ways to modify our environment to improve survival’, which is sort of an accidental super-trait useful for all kinds of environment-modifying tasks not directly related to survival as well.

      The East/West theory seems to be more about a network effect among similarly-challenged populations which drives knowledge accumulation at the society level, on a completely different time-scale to any genetic changes. Presumably the direction of coasts is the thing. This argument seems flimsier though. We have civilisation arising in the Levant around 12,000BC which may even have been before man set foot in the Americas and certainly something like 5,000 years head-start over the first signs of independent Mesoamerican civilisation. If we compare the Aztecs at the moment they met the Spanish with civilisations in Eurasia around 3,000BC is there so much difference?

      The unstable pattern of Rift Valley lakes made me think of Elephants. Pretty wicked intelligence and they seem to use it almost exclusively for figuring out where water, food and shade are likely to be over long distances, and for passing that knowledge on. Maybe that’s where the theory comes from? (I guess I should read the book).

  4. Asenath Waite says

    Seems like North America is still pretty wide, longitudinally. Probably comparable to Europe, especially in the temperate region. And weren’t there ridiculous numbers of bison?

  5. In around 1000 in Baghdad or Cordoba it could sound something like ” well, clearly Franks( i.e. Europe) are such a backward, poor and primitive culture because God gave them such an inhospitable land and climate so cold”

  6. In response to a changing environment the life forms can either (a) go extinct, (b) change themselves/mutate or (c) change the environment or (d) move to another environment.
    So whenever the argument goes simply like a ( b,c or d) happened because the environment changed the argument sounds rather vacuous.

    • Andrew Scott says

      That was very similar to my thought. They could just migrate to where the foliage was higher, but instead they involved massive brains that can discover electricity and use it to power automated bowling alleys.

      I wonder how many people stop to think about how something so purely imaginative and speculative gets passed off as science. If this were any other subject more people would apply some critical thought, but this one gets a pass.

      “But the bigger question, what’s been puzzling paleontologists for a while, is what was it specifically about the Rift Valley in East Africa that created us as such an exquisitely intelligent species of ape.”

      And then the proposed answer is that changing climate somehow caused humans. It completely glosses over the overwhelming complexity of the changes required, and asserts that the weather changed and they needed more intelligence, so it evolved. Because, you know, that’s what happens when the weather changes a lot and something needs more intelligence.

      Not only is it a meaningless, hand-waving non-explanation, but it fails to address why other species faced with danger and changing environments didn’t also evolve intelligence many times greater than what they actually need to survive.

      Did no one stop to Google “astrobiology?”
      “Astrobiology is the study of life in the universe. The search for life beyond the Earth requires an understanding of life, and the nature of the environments that support it, as well as planetary, planetary system and stellar processes.”

      No one has ever studied life that isn’t on Earth. There is no “real” biology other than that which studies life on Earth. Consider the nonsense he’s already tried to pass off, and then re-read the definition of astrobiology which is carefully worded to describe what the search for life beyond Earth requires without actually stating that astrobiologists search for it. Because they can’t. Unless life on another planet has been broadcasting signals for thousands of years (not biology), you’re not going to “find” life by studying “stellar processes.” Trust me, that nebula over there, that’s the spot. You’ll see in 2,000 years when our descendants get there. Would you like me to sign your book?

      Science is a method. Pay attention when someone skips over the method to a conclusion and tells you that the conclusion is science. Especially when it’s as over-the-top crazy as this.

      • Yup. Most science today is pretty blatantly non-scientific. I recommend Owen Barfield’s book Worlds Apart if you want to know how really nonsensical most of it is.

      • staticnoise says

        @Andrew Scott
        It never fails to amaze me as to how much speculation is involved in scientific declarations. Astrobiology is a great example as you point out. Cosmology is another that lives and breaths wild speculation that is then parroted as fact for decades. The ‘dirty snowball’ comet is a prime example. It was a hypothesis decades and decades ago that has been disproved repeatedly (most recently comet 67p) where photos and collected material have shown comets are rocky bodies with the physical make-up similar to the inner rocky planets, yet the notion of the dirty snowball prevails.

        The guiding hand of science is supposed to be skepticism – we lay people should approach scientific declarations with a healthy dose of skepticism ourselves.

  7. Etiamsi omnes says

    Excellent article! The kind that makes Quillette such an iinteresting and valuable site. As long as you stay away from the comments’ section as much as possible.

  8. Asenath Waite says

    “And it stands to reason that if the conditions on Earth were appropriate for chemistry to become biochemistry to become life, then that wouldn’t have happened at just one location. It would’ve happened at several locations.”

    Unless it was a highly improbable process that wasn’t likely to have occurred at all on Earth but just happened to in one instance, against all odds. In that case we would not expect multiple instances of abiogenesis to have occurred in different locations on Earth.

  9. Mike says

    I tried to listen to Guns, Germs, and Steel on audiobook during a long drive a decade ago. I found it so full of illogical arguments and conclusions that I declined to finish listening to it. I am rather skeptical of anyone who describes it as “a great book.”

    • Andrew Worth says

      I got perhaps a quarter of the way through GG&S battling with the same problem, I did manage to complete Diamond’s book Collapse, but much of that book is looking dated today with predictions that were oh so wrong.

  10. Andrew Worth says

    I disagree with this focus on some need for East-West distances, in the ancient world of the earliest civilizations people didn’t migrate, indeed civilization was the opposite if migration, people became more fixed.

    My take: If you want to build a civilization the first thing you need to have is a natural defense against the barbarians and other marauders:

    If you look at the geography of places that have produced the great civilizations of the past you see cradles of civilization, with the emphasis on “cradles”, each society that developed into a great civilization was to some degree isolated, protected, from the peoples around it by geography, this semi-isolation both protected the increasingly wealthy developing civilization from plunder and served to create national identities, if you look at Europe, East Asia, Japan, South Asia the geography is broken up by mountains and seas, if you look at the Americas the Aztec and Inca civilizations were also protected from their neighbors by terrain. Terrain that served the same function as an egg shell or front door, allowing the control of who enters.

    If you then go and look at languages where civilization developed you get large geographical blocks with people speaking the same language, helping to build large blocks with a common identity.

    But when you look at Africa and most of North America there are few or no inland seas, there are no mountain ranges to speak of that create protected areas, in North America and Sub Sahara Africa languages flow from one to the next across the continent, the only part of Africa that was geographically semi-isolated from neighbors was North Africa, with the Mediterranean to the north and the Sahara to the south. In |Sub Sahara Africa even small countries are ethnically diverse, with a huge number of small tribes each occupying a small area.

    Agriculture is perhaps the first step towards building a civilization as it yields far higher returns in food for the effort put in than with hunting/gathering, this gives people leisure time, time to think contemplate and invent, it enables a society in which a smaller fraction of the population is devoted to food production with other people being able to specialize in other endevours. The development of agriculture though is very vulnerable in an unstable setting, livestock are vulnerable to poaching, you have to wait for months for your crops to grow, if there are no clear boarders controlled by your government your farming enterprise is more vulnerable, the risks too high, better to just hunt and gather.
    It takes a large group of people sharing a common identity living without a continual threat from neighbors – stability – to build a civilization.

    • Stephanie says

      Andrew, great comment, I think that’s a more persuasive argument than the book’s author made for why advanced civilizations developed. The Great Plains of North America provide plenty of room with similar agricultural conditions for a civilization as large as Babylon or Egypt to develop.

      Something else I wonder about that is possibly related is why some societies invented the wheel and others didn’t. Geography can explain it for some (the terrain wasn’t conducive for Mayans and Aztecs), but not for others, like the Plains Indians. Nomadic cultures living on flat glasslands should really have developed the wheel. Why didn’t they?

      • Stephanie says

        I got curious and read up on what people thought about it. Seems like domestication of animals is the pivotal factor. The Americas, Africa, and Australia generally lacked animals suitable for domestication. A wheel is kind of pointless without a wagon, and a wagon is pointless without an animal to pull it, so without domesticated animals there wasn’t a point to the wheel.

        Domesticated animals also lead to more efficient agriculture, which allowed for more humans to do work that didn’t involve producing food. Most of our most deadly infectious diseases came from domesticated animals, so Eurasians ended up immune to those by the time they arrived in the New World, introducing diseases that killed off 95% of the local population before Europeans ever even came into contact with most of them.

        The N-S versus E-W dynamic seems important too, but the real luck of the draw seems to come from the presence of animals that can be domesticated.

    • Aylwin says

      The point about E-W distances doesn’t require populations to move, it requires technology (in this case, the breeding of plants and animals) to move (e.g. by trade). Traders might move significantly relative to people within settled areas, but what is really making the difference is the movement of knowledge and tech, and that movement is not restricted by the lack of movement of populations, nor even by the limits of traders, because traders are just the links passing on the tech.

      • Andrew Worth says

        @Aylwin, I’m talking about the very start of a civilization when it shifts from a hunter – gatherer to an agrarian society, what you’re refering to comes later, when the society becomes more technologically advanced and trade develops.

    • mcswell says

      “If you then go and look at languages where civilization developed you get large geographical blocks with people speaking the same language.” I don’t think that’s true at all. There were probably many languages across ancient Europe, most of which have gone extinct without leaving a trace because they were unwritten. The swaths of people speaking the same language (to the extent that’s true) are the result of the civilizations, not the cause. This was true of the barbarians recruited into the Roman legions, who had to learn enough Latin to communicate with each other and with their officers; of the Latin American indigenous peoples who (with significant exceptions, like the Quechua, and with many smaller exceptions) were brought into the Spanish-speaking realm; and of the indigenous and immigrant peoples of the US who are now largely English speaking. Even modern immigrants into the US mostly have English as their second language in the first generation, and English as their first language beginning with the second generation.

  11. John says

    ..”it stands to reason that if the conditions on Earth were appropriate for chemistry to become biochemistry to become life, then that wouldn’t have happened at just one location. It would’ve happened at several locations.”
    How does it stand to reason?
    Ed Witten was asked what he thought the probability was of discovering the Higgs boson.
    He drily remarked one cannot assign a probability to an event that only happens once.
    To the best of my knowledge, the “sterility” of Mars came as a shock to the first investigators in a position to look for life there.
    We infer that life emerged spontaneously from non-life, although we have observed no examples of this in nature, and cannot even replicate intentionally in the lab an event which we ascribe to random processes. To say life on Earth is that example is to assume your conclusion.
    How many times the spontaneous emergence of life will occur is something we can start talking about reasonably when we understand, and are able to replicate the processes involved intentionally.

  12. AJ says

    “And it stands to reason that if the conditions on Earth were appropriate for chemistry to become biochemistry to become life, then that wouldn’t have happened at just one location. It would’ve happened at several locations.”

    It stands to reason that for as long as the conditions for it to occur persisted it would continue to occur. It is not at all clear that conditions would have persisted long enough because life once it arises will change the conditions.

    If the probability of life arising is low so the interval between it occuring is long compared to the timescale with which life having arisen will change the conditions then it can be very unlikely that life does arise more than once. Given life will grow exponentially until the environment is changed the time scale for life to prevent further occurences could be relatively short.

  13. Stephanie says

    Sounds like a fascinating book. I have a friend who will enjoy it very much, I’ll see about sending him a copy.

  14. Colonel of Truth says

    I don’t buy the argument re lack of animals suitable for domestication. Is a zebra so radically different from the original wild horse stock? Are wolves, from whence the domestic dog originated, a natural choice for domestication? Chinese fisherman used otters to aid in fishing a thousand years ago. And bison, as someone has already pointed out, are domesticated / harvested even today.

    I don’t think scientists today are in a position to opine on the relative suitability of various species.
    A more logical answer might be the relative ability for the requisite impulse control on the part of the various regional populations.

    • More logical perhaps, but goes against the gospel Diamond et al are tediously engaged in disseminating, i.e. that race is unreal because of flora, fauna and geography.

  15. Colonel of Truth says

    Agreed – and explains the wild popularity of GGS. A palliative for those unwilling to consider unfortunate thruths.

  16. Jeremy Ashford says

    Could the reality be as simple as the rise of capitalism (through surplus) created civilisation? And the fall of capitalism will eventually lead to its demise?

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