Book Club: Darwin’s Unfinished Symphony, 7, the dawn of civilization

Egyptian agricultureHomo sapiens is the only species on planet Earth to have experienced three phases of evolution: the standard biological one, driven by mutation and natural selection; gene-culture coevolution; and now the period of evolution driven primarily by culture. This is how chapter 10 of Kevin Laland’s Darwin’s Unfinished Symphony: How Culture Made the Human Mind, begins the transition to the author’s discussion of that very last, novel, and crucial phase. (More entries in this ongoing series here.)

It’s an obviously crucial topic for a variety of reasons. First off, to help explain why on earth we evolved such large and metabolically expensive brains. Keep in mind that the human brain accounts for only 2% of our total body weight, and yet it consumes a whopping 20% of our daily caloric intake. (It’s unfortunate that thinking harder doesn’t lead to weight loss…). Second, as Kevin has documented in the previous chapters of the book, it is our capacity for social learning (and teaching) that accounts for the incredible success of our species, as the third mode of evolution is what has made possible for us to build giant cities, go to the Moon, and waste our existence on social media.

Kevin begins by addressing a related question: why did it take so long for our species to develop complex civilizations, while hunter-gatherer societies still today have very limited technology and simple cultures? The likely answer has to do with the severe limitations imposed by a hunter-gatherer lifestyle. To begin with, of course, hunter-gatherers have to be constantly on the move, changing base location once the local resources are depleted. This means that it is impossible to settle down long enough to develop a large population size and the division of labor that foster new technological developments. And even if some new technology were to be developed, it would have to be of limited size and complexity, again because the entire population has to pick up and move every few weeks or so.

Similarly, in hunter-gatherer societies the birthrate is typically low, with new pregnancies well separated in time, as a human female cannot carry and care for many small children when the group is constantly on the move. Small population size and temporary abodes also means no accumulation of wealth of the kind that makes division of labor possible, leading in turn to the origin of specialized classes of workers that can rapidly accumulate specific technical knowledge over few generations.

“This helps us understand why hunter-gather technology was only slowly changing for such a long time, and also why, even today, many small-scale societies possess limited technology. Hunter-gatherers are effectively trapped in a vicious cycle that severely constrains their rate of cultural evolution.” (p. 248)

That’s also why the invention of agriculture, which took place multiple times after the last Ice Age, is tightly linked with the origin of complex human technological cultures. The reason agriculture did not originate earlier is because the conditions following that Ice Age, about 11,500 years ago, have actually been the most favorable — climatically speaking — for such an event over the last two million years of hominid evolution. And before then our ancestors simply did not have the required brain power and ability to communicate through language.

Plant and animal domestication of some sort preceded the full blown agriculture revolution, and the first plants to be domesticated were annuals, characterized by a rapid life cycle and hence easy to select artificially. These included peas, wheat, rye, barley, and maize. A new form of wheat, for instance, appeared around 9,600 BCE in the eastern Mediterranean region. Maize was farmed in southern Mexico around 9,000 years ago. Millet appeared in China between 10,300 and 8,700 years ago, rice around 9,000 years ago.

The invention of agriculture was not without its own problems. The more stable source of food led to population explosions, which in turn caused periodical famines. Indeed, the archeological data show that Europeans became shorter by about 7 cm. between 2,300 and as little as 400 years ago, because of poor nutrition.

As Laland points out, agriculture is a great example of niche construction on the part of human beings. The old idea, in ecology, that niches are “out there,” waiting to be filled by new species of organisms, has been questioned for some time now. Rather, living beings actively alter their environment, co-evolving with it, if you will. By far the most spectacular example in the history of earth is the fact that we have high levels of oxygen in our atmosphere, a byproduct of photosynthesis, an organic process that has made animal life possible in the first place.

Since agriculture was not an unqualified good, it is reasonable to ask how come the new mode of life largely and rapidly replaced the old hunter-gathering. Kevin offers two main reasons: first, agriculturalists simply outbred hunter-gatherers, because of the larger population size made possible by a sedentary lifestyle. Before the advent of agriculture the world’s human population had stabilized at around one million people. By the time of the Roman empire it was up to 60 millions.

The second factor was a wave of innovations triggered by agriculture. For instance, the invention of the wheel, which appeared simultaneously in Mesopotamia, Russia and central Europe around 5,500 years ago. The first organized religions also sprang in agricultural societies, with different cultures, predictably, worshiping gods related to agriculture: Inti, the sun-god of the Inca; Renenutet, the Egyptian god of harvest; Ashnan, the goddess of grain in Mesopotamia; and Ceres, the Roman goddess (counterpart of the Greek Demeter) who was credited with the discovery of wheat, the invention of ploughing, the yoking of oxen, and similar.

Here is another way to appreciate the difference between pre- and post-agriculture humanity:

“Prior to the advent of agriculture, each population would have possessed at most a few hundred types of artifacts, while today the inhabitants of New York are able to choose between 100 billion bar-coded items. … One recent estimate of the amount of information now stored on the internet is 1,200,000 terabytes.” (p. 263, 269)

Kevin points out that all this innovation has had dark sides, including environmental destruction, not just today, but throughout the last 10,000 years or so, with humanity being responsible for countless extinctions of other species; as well as of course the scale of war that technology has made possible; and the increasing inequality (compared to hunter-gatherer societies) among human beings themselves. It seems like both natural and cultural selection don’t really care about ethical considerations, although of course we should. But that’s another story.

Categories: Book Club, Philosophy of Science


51 replies

  1. garth,

    “No thanks. Based on some of the quotes you presented It sounds too ideologically motivated for my taste and lacking the data to support it’s bravado.”

    Said the pot while calling the kettle black.

    “Nevertheless lactose tolerance seems to have evolved the old fashioned way. Natural selection, likely sped up by famine.”

    You refuse to understand the very concept of gene-culture coevolution. A genetic mutation favored by a cultural change is genetic evolution driven by culture. That’s the definition of it. And there is no evidence at all that the event (which happened multiple times) was driven by famine.

    Liked by 1 person

  2. WTC: The lack of brakes is actually a selected-for design feature that became standard on the Homo sapiens model during this period called the “EEA.” Steve Pinker said that’s how he’s able to inform the average non-violent Joe that he has so much enlightenment about Enlightenment. He writes that so well because of his massively modular Language Instinct.

    Good enough, Massimo? 😉

    Liked by 1 person

  3. A genetic mutation favored by a cultural change is genetic evolution driven by culture.

    I must confess I have some difficulty with this concept. In some cases, I think it’s not problematic, but in others, I don’t know.
    Genetically modified soy, intensive breeding programs for cattle or dogs, settlers arriving on an island and exterminating 30 % of the fauna (removing its genes entirely), conquerors spreading their genes by raping the women of the vanquished, settles burning down tropical forests and replacing the local flora with (perhaps genetically modified) crops and so on.
    Is this genetic evolution driven by culture, by definition?
    All this is certainly driven by culture. And it changes the genetic make-up of local fauna & flora (humans included). But where’s the evolution? Nothing that happens in these examples contradicts evolution theory, but then, very few debates about culture contradict particle physics and the idea that we’re made of particles.

    Liked by 2 people

  4. Bottom up dynamics and top down structures. We either keep expanding the models and frames, or breaking and discarding them.

    Monarchy tried to rein in some of the more disruptive aspects of hierarchal competitiveness, by making the top job hereditary, but that had its pros and cons. Now we have wealth accumulation as the status hierarchy and it seems to have its flaws, but other than general unhappiness, no one has much in the way of alternatives. The ones accumulating the most money necessarily get it by being singularly focused on what they do best, so are not the ones to look over the horizon and propose other paradigms, beyond colonizing other planets, of course.

    Looks like it will have to be a wave that has to crest, before we see what comes next.

    So, not only are we subject to the morals of apes and rats, but ultimately, elemental wave action.


  5. Garth said:

    But how does this demonstrate that we are therefore “far from stuck” with ancient emotional and intuitive traits that evolved millions of years before we were even human?

    Isaiah wrote:

    He said, “Go and tell this people:

    “‘Be ever hearing, but never understanding;
    be ever seeing, but never perceiving.’
    Make the heart of this people calloused;
    make their ears dull
    and close their eyes.[a]
    Otherwise they might see with their eyes,
    hear with their ears,
    understand with their hearts,
    and turn and be healed.”

    Dang, it’s great being a secularist who still knows how and where to quote his bible.

    And, that IS my response, Garth.


  6. garthdaisy

    Does the fact that changes in neurotransmitters have accelerated in the last 10,000 years somehow negate the evidence that our drive to climb social status hierarchies is a trait that evolved millions of years ago?

    We have a drive to climb social status hierarchies? Why didn’t I get the memo?

    Liked by 2 people

  7. Robin,

    Playing king of the hill takes a mindset we are not all privileged enough to have.

    Though with 7 billion people, there are more than enough who do.

    Liked by 1 person

  8. Robin,

    We have a drive to climb social status hierarchies? Why didn’t I get the memo?

    Because you weren’t on the distribution list! (think about it)

    Liked by 1 person

  9. Couvent2104 asked “…culture…changes the genetic make-up of local fauna & flora (humans included). But where’s the evolution?…”. I’m at a disadvantage, not having read the book, and further being more towards the “nothing that new here” camp. However, to my mind, the interesting bits are where processes continue over time, and there are feedback loops between different levels. So, lactase persistence increases success of the culture of milk production, which then further alters the selection against those lacking lactase. Same for rice and ADH1B, corn and ABCA1. With persisting assortative mating (behavioural level) for a metric trait, one gets persistent changes in the distribution of the relevant alleles (genetic level) in the population, that is different from what you get with homogamy (where mating is limited by geography or cultural group). You might also know that genes where mutation causes intellectual disability are disproportionately on the X chromosome – which has been hypothesized as reflecting sex selection for IQ. In families, we can detect sibling interaction, where family members who are more similar genetically “choose” to behave differently – again we detect these by shifts in trait distribution variance.


  10. There has been some discussion of why we should consider cases like the evolution of adult lactose absorption instances of gene-culture coevolution, rather than standard biological evolution in which environmental stressors (e.g. famine) impose selection on human genes. The simple answer is that there is strong and convergent experimental, statistical and theoretical evidence that supports the gene-culture coevolutionary account and not the standard biological evolutionary account, comprising over a hundred published scientific papers. If anyone would like to track down this data, or read more about the evidence for gene-culture coevolution, a good starting point would be a paper of mine in Nature Reviews Genetics (‘How culture shaped the human genome: bringing genetics and the human sciences together’, 2010, 11: 137-149). The paper, which features dairy farming and lactose tolerance, illustrates the wide range of methods that provide evidence of gene–culture co-evolution, including anthropological and demographic studies of the covariation between cultural practices and human phenotypes; detection of a variety of statistical signatures of recent selection by geneticists; analysis of ancient DNA to determine whether ancestral populations possessed putatively adaptive alleles; statistical estimation from genetic data of the magnitude of selection pressures; biochemical analyses; analyses of genetic variation in animals (and plants) that have co-evolved with humans; and mathematical models of gene–culture co-evolutionary processes using population genetic and phylogenetic methods.

    Let me illustrate how these kind of analyses can differentiate between alternative causal accounts of evolution. Lactose tolerance is frequent in northern Europeans and in pastoralist populations from Africa and the middle East, but is almost completely absent elsewhere; these differences relate to genetic variation near the lactase (LCT) gene. A SNP located 14 kb upstream of LCT has been shown to be responsible for lactose tolerance in Europeans, and several nearby SNPs associate with lactose tolerance in African and middle Eastern dairying populations. There is no question that adult lactose tolerance is a genetic trait.

    If, as has been mooted, selection on LCT derives from non-cultural environmental sources, such as famine, then responses to selection, and allele frequencies, around the world should co-vary with the incidence of such environmental variables – but they don’t. Conversely, if the gene-culture coevolutionary account is correct then responses to selection, and allele frequencies, around the world should co-vary with the incidence of dairy farming – and they do, as countless studies attest. Comparative phylogenetic analyses also support the gene-culture coevolutionary account, revealing that dairy farming evolved first, which then favored lactose tolerance, and not the other way around. Moreover, the best-fitting models are those that treat the source of selection on the gene (i.e. dairy farming) as a dynamical variable that coevolves with the gene variants. Collectively, the data make a very strong case.

    Another issue raised is whether gene-culture coevolution applies to psychological traits. It is certainly true that there are fewer well-researched cases of gene-culture coevolution that relate to psychological traits, but I think that is because the genetics of psychological traits are more complex, and the bounds of psychological traits more diffuse, rather than because there is little evidence that culture is an important source of selection on the brain. In my book I document extensive evidence for selection on the brain, much of which is highly variable across societies in a manner consistent with gene-culture coevolution. A good meta-analysis of this data is required to confirm gene-culture dynamics, but such studies are in the pipeline. Interested readers could look out for a series of writings on this issue from the recently emerging fields of cultural neurobiology and cultural neuroscience (see Causadias J et al, eds., 2017, The Handbook of Culture and Biology, Wiley, for a great introduction).

    In sum, demonstrating gene-culture coevolution conclusively is no trivial matter, and requires substantial interdisciplinary effort. The challenge is even greater for the psychological traits compared to traits with a simple genetic etiology, such as lactose tolerance. Nonetheless, even here, evidence is starting to amass, and I suspect we will reach the point where the case for the gene-culture coevolution of human cognition has become overwhelming within the next 5 years.

    Kevin Laland

    Liked by 8 people

  11. Being “king of the hill” is likely a common drive, but everyone has their own definition of “hill”. 🙂

    Liked by 2 people

  12. Thank you Kevin for a masterful recapitulation of the themes in your book. Since I am slow, lazy, and only of moderately above average ‘intelligence’, I have decided a long time ago to rely heavily on the work of others that are more committed to, and knowledgeable of, their fields. (Experts.) But I do reserve final judgment in all matters on this earth for myself, since this is the way the mind seems to work.

    Thank you!


  13. Philip,

    I would say there two interrelated drives here.
    One to compete for specific goals, but also to expand out and explore new territory, or simply to fill unoccupied niches. Then the feedback between the two, creating a process of expansion and consolidation.


  14. Massimo

    “You refuse to understand the very concept of gene-culture coevolution”

    Not at all. Gene-culture coevolution is clearly a thing since culture is not only part of the environment, but a part that we have great control over. So I get the whole feedback loop situation. It is Laland’s extrapolation from this that I am having trouble reconciling with the data he provides.

    “And there is no evidence at all that the event (which happened multiple times) was driven by famine”

    What drove it? Just milk drinking? Just the culture? A lot of people had to die and not procreate from not being able to drink it or from getting diarrhea after drinking it. Do we really know this was not caused mostly by famines? Everything I am reading (besides Laland’s book) says the science is still unclear on this. I can see why Laland wants to present it as more clear than it is.

    But lets say Laland is right on lactase. How does this mean we are no longer stuck with psychological traits that evolved millions of years ago? This is what Laland is claiming follows from this evidence he is presenting.


    “And, that IS my response, Garth.”

    In what way was that secular? Quoting the Bible (especially that quote) is exactly what religious people do when faced with a valid question they can not answer. That was about as religious a response as I have ever seen.


    “It is certainly true that there are fewer well-researched cases of gene-culture coevolution that relate to psychological traits”

    So why are you presenting research on non-psychological traits to declare that ev-psych is wrong and we are far from stuck with psychological traits that evolved during the Pleistocene or earlier, because of this evidence you present for a “quicker form of evolution” demonstrated by lactase and right handedness? Why did you not present evidence of this “quicker evolution” occurring in psychological traits before you declared an entire field out to lunch? Where is your evidence for “remarkable plasticity” in the kind of psychological traits that evolved over millions of years?


    “We have a drive to climb social status hierarchies? Why didn’t I get the memo?”

    Strange, Robin, because that memo went out when we still shared a common ancestor with the lobster. Lobsters get a shot of serotonin when their group status gets raised and a shot of cortisol when it is lowered. So has every creature that descended from them, which includes monkeys and us. There are always anomalies so maybe thats the manner in which you missed the memo. Most people have compassion but not all people. Some people missed that biological memo, so to speak. You may be an anomalous biological creature. If you look around however, you should notice everyone else rabidly climbing the social status hierarchy ladder because they are driven to do so by their genes.


  15. Garth said:

    Does the fact that changes in neurotransmitters have accelerated in the last 10,000 years somehow negate the evidence that our drive to climb social status hierarchies is a trait that evolved millions of years ago?

    As a textbook example of cherry-picking, nobody said that accelerated changes in neurotransmitters were even close to being limited to climbing social status hierarchies.

    In fact, when I posted that link, I noted that said accelerations are believed to be linked in part specifically to growth in population density caused by the establishment of sedentary agricultural societies and the foundation of cities.


  16. garthdaisy

    “If you look around however, you should notice everyone else rabidly climbing the social status hierarchy ladder because they are driven to do so by their genes”

    Can’t say that I do.

    I see certain people who are social climbers, but in general “social climbers” is used as a term of ridicule.

    In general most people around me seem to be happy with their social niche, so it doesn’t appear that I am an anomaly at all.

    That seems a common problem in ev-psych, the behaviours that we are allegedly genetically determined to do don’t seem to be evident as general behaviours.

    Do you know of any research to show that people in general are rabidly climbing the social status hierarchy?

    Liked by 1 person

  17. Garth,

    “our main goal in life is still to climb the status hierarchy so we can mate well”

    But the science is light years from supporting that kind of a statement.

    Liked by 1 person

  18. Garth,

    Cortisol/serotonin, expand/contract.

    It seems there are complimentary impulses here. If the only drive was to climb the ladder, wouldn’t we kill each other at a much more compulsive rate?

    Personally I was a younger child in a large family and very early on recognized competing was a poor strategy and naturally sought out situations and activities where there was more space and less stress.


  19. The last common ancestor between humans and lobsters was, correct me if I am wrong, pre-Cambrian. About 600 million years ago. It is not clear to me that their was anything that would qualify as “social status” 600 million years ago.


  20. Oh, I see, it is a Jordan Peterson idea. I read part of his book. Come back Stephen Covey, all is forgiven.

    Liked by 2 people

  21. Gets the Raid bug spray out to kill the Canadian “crickets” infestation.


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