Meat & trade & per capita income of the Roman Empire

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During the height of the Roman Empire there was a NW-SE (of course mostly west to east) gradient in per capita income. This is well known. One of the reasons given for the collapse of the Western Empire in the 5h century in contrast to the persistence of the Eastern Empire is that the provinces of the latter were wealthier and so could afford initiatives such as bribing barbarian tribes to move on toward the west. In Contours of the World Economy 1-2030 AD Angus Maddison confirms this (table below the fold). Additionally, in Peter Heather’s The Fall of the Roman Empire the argument is also made that expansion beyond the Rhine did not occur mostly because of the poverty of the lands; the lack of tax base meaning that the conquest wouldn’t have been self-supporting. So as you go north there is an inversion of the east-west wealth gradient. The main exception to this clinal geographic distribution of wealth is Italy, for obvious reasons. But there are a few other data which Maddison alludes to which interest me in relation to per capita income. He confirms that Germans were larger and more physically robust because they had more meat and milk in their diet (better sources of protein). Maddison also notes that Roman culinary science which reflected the needs and interests of the elites had a strong focus on condiments and sauces because even imported foods tended to go bad. I know that the Dutch became wealthy in the early modern period in part by exporting salted herring, but these data seem to imply that the Roman trade in food was mostly in grain. Unless curred or salted it seems that vegetables and meats wouldn’t make it. If there had been magic preservatives perhaps those in the wealthier provinces would have purchased milk & meat to shore up their nutritional intake? But decomposition constrained the possibilities for trade across long distances in such perishable food stuffs.

I bring this up because in Farewell to Alms Greg Clark used the distribution of lactose tolerance to imply that northern Europe had always been very wealthy, since after all milk was produced from cows which indicated a relatively high standard of living where land could be given over to husbandry. Now, Clark is obviously a smart guy, smart enough that Brad DeLong seems to have creamed himself with praise over his book, but that sort of assertion seemed really dumb and reinforces the perception that economists don’t know jack. After all, we have a good idea of the distribution of lactose tolerance and the nature of its evolution, and it seems that ecological constraints and possibly path dependence is very critical in conditioning whether this trait will emerge. In fact, as I note above scholars of the Roman period assume that the lands of Germany were relatively sparsely populated and poor if material data are any evidence (Hitler was irritated with Himmler for funding archaeological digs in Germany and Scandinavia because he felt it just made the ancestors look primitive). Gaul was wealthier and more densely populated. That serves to explain why it remained occupied after being gutted for the glory of Julius Caesar, while the campaigns of Germanicus served mainly to buttress the popularity of his insane son the emperor Gaius (Caligula).

Reading economic history I notice all sorts of glosses and oversimplifications when it comes to cultural details. I don’t mind that too much; I don’t read Maddison’s work for his analysis or even his often tenuous causal claims, but rather for his copious data sets. Nevertheless, when it comes to something like inferring economic conditions from biological data one can work out objections from the armchair without reading historical works. The extrapolation does though require taking non-economic dynamics and conditions seriously, which Clark presumably does.

Note: The estimates below are for 14 AD.


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40 Comments

  1. “Brad DeLong seems to have creamed himself” 
     
    Well, Delong is an economist — thus doesn’t know jack — so his review isn’t a good measure of Clark’s quality. :-) 
     
    Seriously though, let me flesh out Clark’s logic. He is pointing to the fact that there’s a correlation between income and dairy consumption (using modern data). We would expect this correlation to hold in the past because of how expensive dairy is to produce per calorie. On the other hand, it seems reasonable to assume lactose tolerance will be more likely to develop where dairy is important. So, Lactose tolerance is a weak indicator of income levels (i.e. we’d expect a non-negative correlation between the two). 
     
    Pointing to one gradient (NW-SE Eurasia) where this connection doesn’t hold doesn’t disprove his point.

  2. Oh, I should mention that I think Clark uses lactose intollarance to compare East Asia and Europe, not N/S Europe. At least this is the case in the passage I found.

  3. will, if you look at a lower level of granularity it is pretty obvious that the primary issue re: lactose tolerance is probably mostly ecological constraint (is why basques have it, andalusians don’t). assuming ceteris paribus is just wack. anyway, my point is that it was a stupid example, and one that seems to be easily shown to be a weak predictor of income when you think about it from the armchair (e.g., who doesn’t know that tsetse constrains cattle culture in africa?). what holds spatially would likely hold temporally too; if the irish had potatoes 2,000 years ago perhaps they wouldn’t have done the husbandry thing? i mean, the greenlanders relied on livestock not cuz they were rich but because hay would grow in their harsh climate, right? not a sign of wealth, just no alternatives (aside from turning to hunting & fishing, which they refused to do for cultural reasons). i’m aware that in modern times that calorie extracted per unit area as meat or milk is a lot less efficient than plain old cereals, but in the days of yore that’s not what was going on right? am i missing something that’s not obvious?

  4. I agree that lactose tolerance is a weak predictor, but its a predictor nonetheless. Also, I don’t think comparing China and Europe is that granular of a comparison. 
     
    Clark is making a statistical case, so I still don’t see how pointing out specific data points will invalidate his point. 
     
    You may not believe the correlation is very high between lactose tolerance and income (do you think it negative?), but at least his argument makes it more likely that China was poorer than Europe in preindustrial times given China’s levels of lactose intolerance. Given we’ll never know for certain, this type of argument is all we have. 
     
    BTW, Pomeranz is the place to go for the contrary view that China was richer than Europe.

  5. I’m not an expert on preindustrial dairy technology (although I grew up on an almost-modern dairy!), so I can’t answer you’re last question. I just took it as given that in most locales there’s cheaper ways than dairy to get your calories.

  6. You may not believe the correlation is very high between lactose tolerance and income (do you think it negative?), but at least his argument makes it more likely that China was poorer than Europe in preindustrial times given China’s levels of lactose intolerance. Given we’ll never know for certain, this type of argument is all we have. 
     
    i don’t know what the correlation is, but my point is that we know enough about lactose tolerance that it seems pretty clear to me that in pre-modern times the primary predictors were ecological and not economic. today, economics is much more of a predictor. we know a lot more about lactose tolerance today than we did when clark was writing the book, but it just seems that anyone with a knowledge of history and/or ethnography would be careful to assume that the economic calculations of today would be very determinative in the past. the two points i gave, tsetse and greenland are pretty well known and show the primacy of ecology as opposed to economics. 
     
    i have pomeranz’s book and will read it soon. i don’t actually dispute clark’s point too much re: wealth, i don’t care much about that detail. but, the lactose tolerance point seemed really weak. i kind of wonder if he threw that in for the gee-whiz factor. there’s an enormous sample space of weak possible predictors, why not just focus on the strongest causal candidates? i think clark knew that lactose tolerance was really powerful in terms of selection and so if he could add that to the brief it would make is case for strong economic disjunction seem more sturdy. the problem is the strength of selection has everything to do with ecological conditions and not economics from what i can tell.

  7. I’m not an expert on preindustrial dairy technology (although I grew up on an almost-modern dairy!), so I can’t answer you’re last question. I just took it as given that in most locales there’s cheaper ways than dairy to get your calories. 
     
    i’m not an expert either. but form what i know about history the cattle-driving societies were not the obviously wealthy ones (though wealth was found in cattle). i assume everyone knows about the tsetse fly in africa. and my assumption was that in northern europe cattle were raised in part because the grains of southern and western europe would not flourish there, and those that did were not as palatable to humans (e.g., oats). the lower productivity in grains is why new england and upper midwest focus on dairy, right? or do cattle not flourish further south? or does maize do so well that it is better to grow it for ethanol and cattle feed? 
     
    if no one clears it up in the comments, i’ll look it up myself….

  8. I agree Clark wants very much to be making an evolutionary case and he tended to sprinkle the book with such cute examples. Its significant that he used this page of the book using this example instead of more typical predictors (incidence of plague, bone length, size of empire, type of government, etc). 
     
    In fact, right above the lactose example he mentions some of these other predictors.

  9. he should have shown greg cochran or someone else a draft. that sort of thing sticks out as a weird sore thumb.

  10. Agricultural productivity was lower in northern Europe, especially in the early millennia when Middle Eastern crops hadn’t adapted much while replacement crops like oats and rye hadn’t been domesticated (not until ~2500 BC, I think). 
     
    Pastoral societies could often outcompete farmers, even when farming produced a lot more calories per acre, because they were so good at causing trouble. Farmers usually had to be organized into a strong state to compete and even that didn’t always work. 
     
    Maybe this is what happened to Old Europe in the Balkans.  
     
    But in the northernmost parts of Europe, dairying may have actually produced more calories per acre than grain farming. Certainly true of Greenland, maybe true in Norway.

  11. Not too OT to raise here, perhaps: Oliver Rackham (botanical historian) points out that no-one knows how the woodland of Britain (and, no doubt, much of the rest of NW Europe) was cleared for arable. Americans might suggest ring-barking or burning, but in fact neither works for British deciduous woodland.

  12. In Peter Heather’s The Fall of the Roman Empire the argument is also made that expansion beyond the Rhine did not occur mostly because of the poverty of the lands. 
     
    This can be generalized to the steppe. It is said that the steppe was pastoral because it was too arid to sustain agriculture, but this is not true. The Ukraine is a bread-basket, and this was true during classical times, when the Scythians exported grain to Greece. 
     
    Because of their greater mobility, and because they have no fixed capital to defend, small nomad groups have an immediate advantage over much larger agrarian peoples: they can concentrate their attack on one point quicker than the defenders can reinforce it, and don’t need to defend their rear, whereas the defenders have to defend every point on their line of defense. (On the other hand, for logistic reasons pure steppe cultures can’t manage a sustained attack. 
     
    On the steppe, without natural defenses (mountains, seas) and with an abundance of grazing land for horses,offensive warfare has a natural advantage over defensive warfare. So during many periods the Ukraine reverted to pasture, because while it was agriculturally productive, it was not productive enough to defend itself against nomad cavalry, given the offensive advantages there. Even the most productive agrarian civilizations, with natural defenses and large areas of densely productive agriculture, had difficulty defending themselves against the nomads. Outlying agricultural areas were impossible to defend. 
     
    Economic-determinist theories of history (e.g. Engels’) tend to misunderstand this kind of military relationship — a very poor, underpopulated, economically unproductive steppe society can challenge a very wealthy sedentary society because of these military relationships.  
     
    Or, in short, the steppe’s lack of means of production is historically (politically and militarily) counterbalanced by their wealth of means of destruction.

  13. I’d actually see three axes here. One, W to E, as stated. Two, distance from the Mediterranean and attached seas (rather than N to S) — the poorest northern provinces are inland provinces, whereas if there had been inland provinces in Africa I suspect that they’d have been poor too. Third, northeast to south center, showing vulnerability to steppe attack (Dalmatia and Moesia, which are southern and on the sea, but under attack.) 
     
    So the western pole explains Numidia and Mauretania. The inland pole and the Western pole explain Gaul and maybe Germany.The steppe pole explains the whole contested area west of Anatolia. (Germany suffers from all three.)

  14. Lactose: when all the arable land is in use, there will be minimal stockraising, but before saturation marginal land might be left to livestock. 
     
    It may be that the small populations in these under-utilized areas are better fed, for Malthusian reasons.

  15. My citations of Heather above dropped this clause: the lack of tax base meaning that the conquest wouldn’t have been self-supporting. 
     
    This is critical: conquest wouldn’t have been self-supporting in large part because of cost of defending the territory, especially distant territory. An easily-defensible area no more productive than Germany could be self-supporting.  
     
    Sorry for a garbled post.

  16. “i’m aware that in modern times that calorie extracted per unit area as meat or milk is a lot less efficient than plain old cereals, but in the days of yore that’s not what was going on right? am i missing something that’s not obvious?” 
     
    No I dont think so. Was Ireland richer than China? Places became pastoralist for ecological reasons, and probably stayed that way for cultural reasons. If cattle were a marker of wealth then the rich ( within these poor societies) would have cattle, as a status marker, and their progeny most likely survived – thus lactose tolerence might increase. What the elites probably didnt do was farm in the market gardening sense, that would be hard labour while owning cattle is not. Irish folklore is full of stories about cattle raids. 
     
    Tain bo Cualnge – cattle raid of cooley. An epic old irish poem.

  17. I don’t think you can meaningfully compare standards of living in places sufficiently distant that trade is prohibitively expensive. You get very different results if you say a pound of gold here = a pound of gold there from what you get if you say a pound of steak here = a pound of steak there. 
     
    Eating steak doesn’t select for lactose tolerance anyway, eating cheese and yogurt does. Probably benefits the middle class more than the rich.

  18. the lower productivity in grains is why new england and upper midwest focus on dairy, right? or do cattle not flourish further south? 
    According to Thomas Sowell in “Black Rednecks and White Liberals”, southerners tried going into dairy sometimes, but they were just incompetent at it and much of the product would go bad. 
     
    The distinction between nomads and settled peoples plays a big role in Franz Oppenheimer’s “The State”, which I have put all on one convenient page here.

  19. It may be that the small populations in these under-utilized areas are better fed, for Malthusian reasons. 
     
    yes, that is probably. perhaps the warfare kept population down?

  20. So again, I am looking at the region west of Tunisia / Africa.  
     
    The data refers to 14 AD. This map seems “off” given that Mauretania was a client kingdom, and not a province, until Caligula murdered the king Ptolemy in 40 AD. Wiki tells me that “Caesariensis” wasn’t split off, much less named, until Claudius. (At least they measured it; it looks like they didn’t even try with Thrace.) 
     
    Mauretania / Numidia gained population during the 300s (and the Vandal – Justinianic centuries 400-600, although some of us were calling BS on that). Morocco and Algeria today, along the coastline, are pretty fertile. Their poverty has other causes: overpopulation; corruption; lack of education; the Berbers deal with discrimination and Algerians were being massacred, etc etc etc). As Roman provinces, how bad did they have it? 
     
    Some data to fit into this: As of 14 AD, Juba II was ruling a kingdom which Rome had granted to him. Roman investors, given a choice between this hinterland and a stable, known province like Baetica or Carthage (“Africa”, here”), would I suspect prefer the latter. Only after centuries of direct and stable Roman rule (and barbarians elsewhere) could the region have looked like a better bet than, say, central Gaul. 
     
    So the statistics are probably right, although the map on which they chose to illustrate them is anachronistic.

  21. ross, u should start a blog.

  22. no-one knows how the woodland of Britain (and, no doubt, much of the rest of NW Europe) was cleared for arable. 
     
    Did you ever wonder where the expression “slash and burn” came from? You cut and burn what you can, and uproot the remains. This may need to be repeated a few times, otherwise the forest may recover (especially without uprooting). The French called it essartage.  
     
    Deciduous trees do burn, especially if you prepare them beforehand, and especially in hot summers (yes, even England has some).

  23. The Malthusian trap is probably mostly heavily-taxed land-poor peasants who can’t escape the land (even if formally free) just because there’s no open land. Pastoral populations anywhere (regardless of ecology) are probably better fed and less dense, but in defensible places good for agriculture, peasant agriculture eventually take over, as happened in France, Germany, and Britain between 1 AD and 1000 AD.  
     
    There are ways of processing milk to reduce the lactose load (souring and fermenting). I haven’t seen this discussed and don’t know what its significance is. Mongols rely as heavily on milk products as any people today, though as East Asians they’d be expected to be intolerant.  
     
    The kinds of “spoilage” that supposedly make milk impractical in warm climates also reduce lactose load, and some African peoples raise cattle. Mongols very rarely drink fresh milk; mostly what we’d call yogurt, buttermilk, and cheese, as well as a zero-lactose weakly-alcoholic milk product called kumiss. 
     
    Since all infants are lactose tolerant, lactose intolerance must be a fairly simple switch which is easy to turn back. I’ve also read that babies who are weaned to cows milk instead of away from milk entirely keep their tolerance. Japan has an indigenous dairy industry and milk consumption was increasing up to a point. I’m starting to think of lactose intolerance more as a marker and less as a cause. 
     
    There are a lot of factual assumptions in this post, and I’m not sure of all of them. I’m putting this up for discussion.

  24. I’m already not sure of the “very rarely drink fresh milk” part. But without refrigeration, they’re sure to consume mostly non-fresh products.

  25. Note that I correctly described my fiscal acumen, however.

  26. Wrong thread.

  27. “I’m starting to think of lactose intolerance more as a marker and less as a cause.” 
     
    You’re wrong. It’s entirely genetic.

  28. That’s not what I said. A genetic marker, not a cause of much of anything. If the Japanese are drinking milk, how horrible can it be? And effects on individuals seem variable. You can’t say “People X doesn’t raise cattle because they’re lactose-intolerant”. More, “People X haven’t been raising cattle, so they’re lactose-intolerant.”

  29. toto, Rackham makes two point. (1) No-one knows how it was done. If you know, pass him your evidence (write to him at Corpus Christi College, Cambridge). (2) Most speculation about how it was done is just counter-factual vapouring. He remarks “British woodlands (except pine) burn like wet asbestos; this was so even when the great drought of 1976 coincided with the height of the fashion for burning stubble.”

  30. He remarks “British woodlands (except pine) burn like wet asbestos; this was so even when the great drought of 1976 coincided with the height of the fashion for burning stubble.” 
     
    Of course. Deciduous forest remain damp even after drought conditions. A drought in England is defined as 6 weeks without rain, and the last was years ago. 
     
    Slash, maybe. Burn, no.

  31. Recently it has puzzled me to notice that many supposedly lactose intolerant Asians can drink milk without any problems.  
     
    Is it possible that infants or children are more sensitive and most of the selection for lactose tolerance would have taken place through infant mortality? At least in Finland during the peasant agriculture it was common that babies were weaned quite early and fed unpasteurized cow’s milk instead. Regions were this practise was most common had historically above average infant mortality even though these areas were otherwise relatively prosperous.

  32. Curious, that would account for a very rapid population change for a people which had suddenly access to milk. If the intolerant children were unhealthier and the tolerant children better nourished (because of a new food source), selection would be quite rapid. There might be no increase in fertility or even a decrease, but the ones who lived would mostly be the tolerant ones.

  33. eoin, you can slash away like mad, it doesn’t kill the trees – all you’ve done is coppice them. It really is (as far as I can see) a mystery – who did it, organised how, and what did they live off while they set about it? And what was their purpose? Would they really devote effort to actions whose benefit would probably come long after their own deaths? Were they trying to create pasture and meadow, ending up with potential arable more-or-less by accident?

  34. I don’t understand the mystery about clearing land. During the years between 1 AD and 1000 AD a lot of land was cleared. Cut trees can be used for firewood or for lumber. I imagine that the absence of steel axes is what people are talking about, but that’s not an unsurmountable difficulty.

  35. I’d imagine they used a Pickaxe, as this way they could dig around a tree and chop through a few vital roots, and have the tree keel over. 
     
    I’ve used this method myself on a few occasions, while growing up on a farm and clearing a 6 acre piece of woodland.

  36. Exactly – I agree with John J Emerson – the process can be seen even today in the 3rd world where people progressively clear areas out looking for firewood. Also, as noted the lack of axes and steel tools isn’t a terrible problem. You can kill large trees pretty effectively by girdling them – cutting the bark and outer layer of wood – all around near the base. After that wait for the tree to die and dry out. It was used at times in North America where trees were to large to easily cut with axes, or when manpower available for that task was insufficient. After the tree is dead and dried it is much more brittle and can be pulled over more easily by cutting it with an axe and pulling it over with animal power. Another alternative is to girdle all the trees in an area at the same time, wait for them to die and dry and then burn them down (although you cannot then use the wood for other purposes) These are long term projects, but not beyond the scope of an individual farmer or small community – girdle a few trees each year, and then fell the trees you girdled 2 years ago at the same time. After you fell the trees, burn the stumps out. burning stumps out is pretty basic stuff – I do it at home. If it’s to damp for you to burn the stump out, then it will decay from mold and fungus in a few years, and then you can pull it apart with your bare hands.

  37. I have used pconroy’s method to. It only works easily for smaller trees though. For really large trees like many of those in a virgin hardwood forest it doesn’t work well. However it’s great for knocking off the smaller trees in the area. It can work for somewhat larger trees if you have some patience – dig around the base of the tree and sever the roots that are growing outward and serve to stabilize the tree. Try to pull it over (with a tractor in modern times, with some oxen or neighbors in ancient times) If it won’t pull over, wait until after some really heavy rains soften the ground and try it again.

  38. “You can kill large trees pretty effectively by girdling them – cutting the bark and outer layer of wood – all around near the base.” No, no, no: that kills many American species but not British ones. The bloody things don’t die they just throw up new stems and carry on growing. A sizeable British deciduous tree is a recalcitrant object. (On a different note, the historian of the Dark Ages, John Morris, suggested that even Germanic tribes, who were equipped with steel tools, found the labour involved in woodland clearance excessive and preferred to steal land that someone else had already cleared. Whether he viewed himself as a spokesman for the Roman British or the Slavs I don’t know.)

  39. bioIgnoramus – are you aware that the species of trees in Eastern North America and Western Europe are very similar? Yes, the stumps/areas below the girdled section will put out new shoots and keep growing. That doesn’t stop the sections above that from dying though. And as both I and pconroy have mentioned it is a lot of work. It probably is easier to take land from somebody else if that is a reasonable option. If there is enough cleared land to grow food for everybody already present, then the labor involved in clearing more land may not be worth while. However if population growth or competition for status, or the development of a taxation scheme makes it attractive to clear the land, then it is certainly capable of being done.

  40. I think that it’s worth asking why the settlement of the northern forests proceeded slowly, but I don’t think that technical difficulty was the main reason. Various combinations of undermining, cutting, and fire can do the job, and timber has its value. Perhaps the drain of population toward the imperial south had something to do with it. And certainly the easily-farmed areas were farmed first.

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