More recently, environmental concerns have become popular, with deforestation and soil erosion proposed as major factors, and destabilizing population decreases due to epidemics such as early cases of bubonic plague and malaria also cited. Global climate changes of 535-536 http://en.wikipedia.org/wiki/Fall_of_rome

http://en.wikipedia.org/wiki/Climate_changes_of_535-536

True.

Returning to the larger thesis: I think that there are three basic trends at work:

1. The accumulating negentropy from the sun. That should produce a linearly increasing degree of complexity in the biosphere.

2. The improving ability of the biosphere (including humanity) to efficiently capture negentropy from the sun. This increases the growth of complexity from linearity to something with a positive second derivative.

3. The occurrence of perturbations (meteors, orbital shifts, continental drift, volcanic eruptions, plagues, wars, short-lived heirs to the throne, etc). These perturbations come at random times and with random degrees of severity. Really big ones cause mass extinctions; minor ones cause revolutions (bad harvests in France in the late 1780s, for example). These perturbations punch valleys into the upward-curving progress of complexity, generating setbacks of various magnitudes.

When we limit our view to human civilization, I don’t see any particular reason why it should be invulnerable to perturbations large enough to destroy it. Indeed, I find it difficult to believe that a species that evolved to fit a hunter-gatherer ecological niche should be capable of maintaining a complex technological civilization indefinitely. Humanity could well wipe itself out, which we humans would regard as an infinitely large catastrophe, but life on earth would keep going from there, and the curve of complexity of the biosphere would simply resume its slow rise.

The big question that captivates me concerns our ability to generate self-destructive perturbations. I’m not particularly worried about an external perturbation (meteor strike, big volcanic eruption, etc) taking out humanity. The fascinating theoretical question is, can a system of accelerating complexity maintain stability? My gut says that no increasingly complex system can preserve its stability, but I can’t wrap my head around the problem well enough to come up with a rigorous answer to that question.

Nothing surprising actually. The Western Empire’s very high military expanses for the protection of its very long and dangerous northern borders from the barbarians returned as heavy tax burdens on its citizens’ shoulders. So if Adams is right, the very source of the problem also becomes its solution, what a diabolic destiny for the Western Empire!

your point taken, but who was doing the writing? a different lot than the average bear.

Razib, a quibble. You said: The reality is that for most of history for most people there was very little change from generation to generation. Malthus reigned supreme. Values were timeless, and quality of life was unchanging…

From our distant perspective this seems true, but from the local perspective probably not. Read the accounts written by the ancients themselves and all seems in constant flux. Wars, famines, plagues. Life was pretty exciting.

I am referring to the Western Empire here.

Eastern border of course had its own disadvantages, but I think in the aggregate it was much more advantageous than the northern border.

the cliometric data is pretty robust that by the 4th century the domains of the eastern empire were far wealthier than those of the west. this is mostly aggregate wealth, though on a per capita basis the eastern provinces may have been marginally more wealthy because they were closer to trade networks which provided goods

I already acknowledge these. What I am saying is that the conditions in the borders had a big role role in that economic weakness.

as a follow-up #2, the eastern empire routinely bribed barbarians to not attack, and sometimes even bribed them to attack the west in preference to the east. concerted groups of barbarians really had little difficulty in ravaging the whole balkans down to greece if the imperial forces were concentrated to the east

The Balkan border was clearly the weak spot of the Eastern Empire, but it was short compared to the northern border of the Western Empire, and Constantinople was very hard to conquer.

the main issue is that i think geography is hard to disentangle from economics, insofar as it may be that the reason that the eastern tax base remained robust is that its geographic lines of control prevented as many “breakthroughs” by barbarians.

Economics and geography indeed have a strong interrelationship. Stable borders bring more prosperity and prosperity determines to which border to give priority.

1) a “standard model” (which i’m actually skeptical of) is that in fact the eastern border was the difficult one because of a real power, and the rise of sassinid persia, diverted resources from the european borders

2) the cliometric data is pretty robust that by the 4th century the domains of the eastern empire were far wealthier than those of the west. this is mostly aggregate wealth, though on a per capita basis the eastern provinces may have been marginally more wealthy because they were closer to trade networks which provided goods

3) as a follow-up #2, the eastern empire routinely bribed barbarians to not attack, and sometimes even bribed them to attack the west in preference to the east. concerted groups of barbarians really had little difficulty in ravaging the whole balkans down to greece if the imperial forces were concentrated to the east

the main issue is that i think geography is hard to disentangle from economics, insofar as it may be that the reason that the eastern tax base remained robust is that its geographic lines of control prevented as many “breakthroughs” by barbarians.

i don’t care about your opinion, you don’t strike me as someone who knows a lot about the topic. so actually offer some data or novel analysis of interest. peter heather would support your contention while adrian goldsworthy would not (his argument is that the size of the armies on paper was far less than their realized strength after the 3rd century troubles). from what i recall ward-perkins tends to see evidence of some incomplete recovery in the 4th century in coin hordes.

now, to convince me you know something about this topic it won’t suffice to just repeat your sincere opinion. i really don’t care about your opinion on any specific topic, i care about the data and analysis you offer into the record. i’m pretty sure i know a lot more about this period and place than you do so your own assessment without elaboration offers no value add (this naturally is addressed to all commenters who offer me their historical opinions on a topic).

this is false. china famously exhibited a nearly concurrent rise and fall with rome in the form of the han dynasty. i agree with your general observation though even if i think you flubbed that detail.

i’ll close this thread if you people don’t get specific and add some value. i’m not interested in your opinions. bob sykes’ comment (#1) was basically a bare-assed assertion which seems highly disputable, and i’ve never seen him express sage wisdom on this topic informed by any deep knowledge. i’m not interested if your opinion-farts people.

here are some books of interest if you want to talk and not fart:
Europe after Rome: A New Cultural History 500-1000
The Fall of Rome: And the End of Civilization
The Fall of the Roman Empire: A New History of Rome and the Barbarians
How Rome Fell: Death of a Superpower
The Inheritance of Rome: Illuminating the Dark Ages 400-1000
The World of Late Antiquity AD 150-750: AD 150-750

naturally this is just a sample of the voluminous literature in this area, but i think it gives you some access to the current scholarship (i find book #2 the best btw in terms of dense concision).

finally, in the general sweep, let’s also remember these issues:

1 – it looks there are anti-entropic endogenous parameters which weaken pre-modern states over their lives. e.g., elite cohesion. this is explored in peter turchin’s work.

2 – there are obviously exogenous shocks. barbarian invasions and interactions with other great powers. anglo-saxon england would have had a different trajectory if not for the norman invasion. in the roman context peter heather is making this argument.

3 – there’s the stochastic element. what if augustus caesar had died of an infectious after the victory at actium? what if one of the antonine emperors before marcus aurelius had had a legitimate son who survived into adulthood? mortality curves were closer to a uniform distribution in the pre-modern period. obviously if institutions are strong, as it was in 3rd century rome, and during much of china’s history, the state can survive a series of short-lived rulers. but i think a series of long-lived rulers with continuity between their reigns probably builds up “capital” stock which can be expended later, and much of this has a random component. the death of constantine iii for example is a case of a an unfortunate random occurrence which may have shifted the parameters in terms of probabilities of whether the western empire would remain robust.