More on a theme

I noted before that Prof. Clark’s non-explanations (as The Economist put it) are a theme around here. Resident superstar blogger notsneaky comments on a previous post and I reply:

Clark has a chapter in his book called “the rise of modern man” suggesting modern (post-Malthusian) people are different than their ancestors in ways you suggest (e.g. they’re more patient, but also smarter, harder working and less violent).

For example, interest rates declined steadily over the centuries. One by one, using the usual Ramsey results on interest rates, he eliminates the possible reasons for this. Growth premium? Nope, there was no growth pre-1800. Risk premium? Nope, the King didn’t really confiscate too much and the characteristics of death statistics didn’t change much in the Malthusian era. Without stating it, the only thing left to cause steadily declining interest rates is changes in time preferences.

He then discusses rising levels of literacy, eliminating the possibility that people were responding to market pressures to increase their human capital… one by one, knock ‘em down… he shows work hours increased and violence decreased. It could only mean one thing… you know, the obvious thing… which was… well you know.

So you could counter Clark by arguing against each of these points, e.g. “yeah, maybe the King didn’t expropriate that often, but when he did it was a big deal, usually accompanied by a disembowelment or two”. Or you can take issue with the Ramsey model itself. But my biggest issue is that Clark never develops a positive theory of the “rise of modern man”, he simply tries a proof by exhaustion showing all the things that couldn’t explain the facts on demographics and interest rates.

To be fair, though, he hints, using testate records, that these deep parameters developed by selection.

To me that’s just a huge can of worms. What is being selected? Genes? Is there a temperance gene? If its genes, are there evolutionary models that select for such sophisticated behavior in just a couple of centuries? Instead were memes being selected? If so, what the hell are those?

28 thoughts on “More on a theme”

  1. Thanks. I was looking for that paper… I don’t think it addresses the questions I raise, though. “Something-or-other” needs to be defined because its not clear that gene selection could account for the emergence of such sophisticated behaviors.

    More likely, norms are being transmitted from fathers to sons, not genes. Rich fathers produce (and raise!) more sons than poor and because of the Malthusian stasis many of those sons have to move down the social ladder. In effect, then, “rich people something-or-other” is being pushed down into the society making everyone more and more like the rich through the generations.

    But do we have a clue about how norms are produced and transmitted? Are sons more likely to act like their relatively rich fathers or are they more likely to act like those in their relatively poor cohort? Do norms flow the other way? Wouldn’t poor sons from rich fathers hate the behaviors (induced by norms) of their rich fathers because they didn’t get them anywhere?

  2. “But do we have a clue about how norms are produced and transmitted?”

    Who said that self replication and evolution are strictly cellular biological processes?

    Sorry — I know that the whole “self-replicating memes” thing has been out of vogue for a few years…

  3. I agree with your concerns and had the same thoughts when I was at the seminar.

    Just to be clear, I think most (including Clark and yourself) think that some third (heritable) factor is likely driving both the increased income and increased fertility. While I agree norms are probably important, I think health is probably the most important factor. Especially since it can explain the increase in income for the first generation (through random genetic variation) and the persistence in future generations (through both parent’s genes and income.)

  4. Really, health? Do you mean behaviors that lead to good health outcomes like washing your hands after going to the bathroom?

    If that’s what you mean, then I’d say those are just a subset of all norms passed from father to son. I have a hard time thinking healthy behaviors explain the IR by themselves.

    Otherwise, I’m not sure what a health gene would be…

  5. “the persistence in future generations”

    The persistence of what? Health outcomes or economic outcomes?

    Clark shows there is no persistence of economic outcomes. In a Malthusian economy, incomes are static. That with the fact that rich dudes are having more kids means the rich dudes kids are poorer than he is.

  6. If you want to argue for norms you have to explain why the “something-or-other” norms of the father leads to both increased incomes and increased fertility. *Perhaps* it is the case that the increased income is itself what drives increased fertility but there is a shockingly small amount of literature on the causal relationship between income and fertility, something I’m working on.

    I think health may be the driving factor because it’s clearly related to both income and fertility and I think the parents income should play some role as a propogating mechanism. I’m thinking:
    (1) good health–>more kids
    (2) good health–>healthier kids
    (3) good health–>higher income–>healthier kids
    What is a health gene? I’m not sure I understand your skepticism. There are tons of genes related to health characteristics from obesity to itching.

    Clark shows that there is no persistence of economic outcomes *on average*, right? (I’m still waiting on my copy of the book from amazon and it’s been awhile since I took his class.) While children of a rich guy may be poorer than their father, it doesn’t necessarily follow that they will be poorer than average. But, yes, someone will have to be poorer.

    Which leads me to what I think is the big puzzle from the way you’re presenting the argument: how do the factors for economic success evolve if they don’t benefit the 2nd generation? I thought Clark argued that the “Industrial Revolution” never really happened and that development actually began long before 1760.

  7. By “I think the parents income should play some role as a propogating mechanism,” I actually meant to say that I think it adds an nice feature to the story but I don’t actually think it’s necessary.

  8. From the NYT review: http://www.nytimes.com/2007/08/07/science/07indu.html?pagewanted=2&ei=5090&en=4c2806a790eb2152&ex=1344139200&partner=rssuserland&emc=rss

    “In support of the disease-resistance idea, cities like London were so filthy and disease ridden that a third of their populations died off every generation, and the losses were restored by immigrants from the countryside. That suggested to Dr. Clark that the surviving population of England might be the descendants of peasants.

    A way to test the idea, he realized, was through analysis of ancient wills, which might reveal a connection between wealth and the number of progeny. The wills did that, but in quite the opposite direction to what he had expected.”

    I guess I’m not sold on the fact that this is in the opposite direction expected by the hypothesis. In other words, I’m not sure I believe that the poor had better health-related genes to pass on to their kids.

  9. Could have sworn I’ve seen studies that imply that greater wealth -> lower biological fertility, even among animal populations.

    I read The Ghost Map a few months ago, which covered a cholera outbreak in London around 1865. One of the observations was that the cholera outbreak disproportionately affected the poor. The poor:

    Lived in much, much, much more crowded conditions, increasing their likelihood of exposure to pathogens.
    Often drank water directly from the river, which doubled as the city’s sewer.
    Relied more on municipal water supplies, a few of which (in this case) were contaminated.
    Had far less access to medical care (being unable to afford it), not that it mattered with cholera at the time.

    A rich family could more likely afford a private well or cistern. A rich family could probably afford to flee to a country estate until an epidemic passed. When germ theory was commonly accepted, a rich family probably had an easier time with sanitary practices: boiling water before drinking, frequent bathing, and buying soap.

  10. After the industrial revolution, the trend changed… rich had fewer kids. Many folks say this is because in the modern economy, the ‘quality’ of children (i.e. education, health, etc) is more important than the quantity. Parents face a trade off between having few kids, lavishing resources on them, or many kids to tend the fields.

  11. “I thought Clark argued that the “Industrial Revolution” never really happened”

    I don’t think Clark denies certain time series went non-stationary about 1800… he just insists that the causes of those hockey sticks stretch back centuries.

  12. I’m still not sure exactly what you mean by “health.” Fitness is, of course, something that gets selected for.

    We’re not explaining physical fitness, which is the usual evolutionary objective, we’re explaining why people became literate or become more patent or whatever. IANAEB (evolutionary biologist), but it seems to me such complex behaviors won’t be explained by gene selection over just a few centuries.

    My complaint with the ‘health gene’ hypothesis (or the any gene hypothesis) is that the changes we are trying to explain happen too suddenly in evolutionary time.

  13. If a fundamental shift did occur rapidly, I agree culture is a good explanation because it is so easily transmitted. At the same time, how does it explain the fact that rich folks had more kids?

    Once again, health ties fertility to the increased income more nicely but is compatible with a more gradual transition. At the same time, it needn’t be as gradual as we typically think about evolution because of the good parent good environment interaction. As I alluded to previously, kids of rich parents can inherit both better health genes *and* better health conditions which would lead to them having both more income and kids. So this process can lead to a relatively accelerated evolutionary process.

  14. Clark seems careful to specify “net fertility” in his paper, and not just “fertility.”

    I suppose the distinction matters in the long run because the investments parents make in childrearing see better returns if more children survive. The genetic distinction between rich and poor certainly looks trivial over a time frame this small. Besides, I thought you needed reproductive isolation for speciation.

  15. I think rich people have more kids is the obvious outcome… more resources means more and better (i.e. healthier) kids.

    I’m still not sure what you mean by “health”. Clark excludes longevity as the cause of rich folks having more surviving children.

    “Thus the greater reproductive success of richer men lay predominantly
    in the fact that they produced more surviving offspring per year
    of marriage, measuring that to the year of first marriage. That could
    come from some or all of three different sources: they may have married
    younger brides, they may have remarried at higher rates if their first
    wife died, or their children may have survived infancy and childhood
    better. We suspect, consistent with the evidence presented above on infant
    mortality across London parishes of different average wealth, that
    differential survival of children was the key.”

    I think the interesting question is: How do literacy and time preferences (and health genes) get propagated through society? Its obvious, at least to me, that rich folks would have more/better kids. Its not obvious why they are rich and why their values/genes would propagate to all classes of people.

  16. “kids of rich parents can inherit both better health genes *and* better health conditions which would lead to them having both more income and kids”

    So, the poor become more healthy over time? If so, why didn’t they too have more kids over time?

    I really think propagation (the how and the what) are the key problems here.

  17. By health, I mean things like being less likely to get sick (especially when young when illness can have long-term impacts on development) and the ability to work longer (or harder) without fatiguing (which may also be related to time-preferences).

    It’s not necessary that rich people’s attributes propogate to all classes of people to see improved average outcomes. As long as rich people outbreed poor people, then average outcomes will increase. Of course, once again, the intergenerational propogation of positive characteristics is only a valid explanation if the change was gradual.

    As a sidenote, I have long thought that time-preferences are the key to a number of questions regarding why some people are successful and others aren’t. I don’t doubt that they have played a large role in shaping which countries have gotten rich while others haven’t. I also think they are likely influenced by genes.

  18. When I took the course, I was was of the thought that there was gradual improvement and that the IR didn’t happen and that there was likely an acceleration rather than a break. This is why we seem to be speaking past one another.

  19. “we seem to be speaking past one another” heh… I gathered that.

    “economically beneficial traits were being developed for no good reason”

    This is dissatisfying if you’re an economist that insists on having rationalizing models to explain even long-term (i.e. multigenerational) changes in the economy. Who, do we imagine, are the agents that are acting rationally in this time frame anyway?

    This is a satisfying result if you’re a sociologist or anthropologist. The problem I have with those fields, though, is they don’t systematically deal with changing norms/culture/etc. I think economics, as the more theoretical branch of social science, needs to develop a theory to fill this vacuum.

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