As I discussed in the previous entry, a recent Guardian blog post (structured loosely as a news article) made worldwide headlines. It was trumpeted by the Guardian blogger as an "exclusive"; he was given a copy of a paper soon to be published in the journal Ecological Economics. Because he didn't provide any context for the paper (the authors were not interviewed, nor were any independent experts), I thought I'd jump into this vacuum. Let's start with the first paragraph of the study's abstract:

There are widespread concerns that current trends in resource-use are unsustainable, but possibilities of overshoot/collapse remain controversial. Collapses have occurred frequently in history, often followed by centuries of economic, intellectual, and population decline. Many different natural and social phenomena have been invoked to explain specific collapses, but a general explanation remains elusive.

Anthropologists are loathe to make sweeping generalizations about the dissolution and/or reorganization of prehistoric cultures. This hasn't stopped popular narratives about carrying capacity from taking hold and remaining immune to mounting evidence that challenges prevailing views. Let's return to the study's abstract:

In this paper, we build a human population dynamics model by adding accumulated wealth and economic inequality to a predator-prey model of humans and nature. The model structure, and simulated scenarios that offer significant implications, are explained. Four equations describe the evolution of Elites, Commoners, Nature, and Wealth. The model shows Economic Stratification or Ecological Strain can independently lead to collapse, in agreement with the historical record.

In other words, overconsumption by elites and/or resource depletion lead to societal collapse, the authors assert. Early in the paper, they walk us through the historical record, citing, among other examples, the fall of the Roman Empire and the crumbling of ancient societies from Southeast Asia to the American Southwest as case studies that suggest "the process of rise-and-collapse is actually a recurrent cycle found throughout history." The question this raises, they write, is "whether modern civilization is similarly susceptible" to a crash. One of the questions nagging at me when I read this study was whether prehistoric societies are appropriate analogues for our 21st century world. Oxford's Steve Rayner, an anthropologist I contacted, provided valuable context:

Whether historical empires were fragile or robust depends on your time perspective and how you divide up historical epochs.

But the authors insist in their paper:

The fall of the Roman Empire, and the equally (if not more) advanced Han, Mauryan, and Gupta Empires, as well as so many advanced Mesopotamian Empires, are all testimony to the fact that advanced, sophisticated, complex, and creative civilizations can be both fragile and impermanent.

Rayner counters:

But China as a civilization dates from at least 2070 BCE, that makes it 4000 years old at present. Just because it has been eclipsed by the west for a mere couple of centuries should not blind us to this. The first Egyptian dynasty began around 3000 BCE and the Ptolemys collapsed in 30 BCE when Egypt was incorporated into the Roman Empire, which lasted another 400-500 years, before itself morphing into the Holy Roman Empire and Byzantium respectively, the latter morphing into the Ottoman Empire. These seem to me to be pretty long epochs in human terms, if not in geological ones. Nothing lasts for ever and arguably while individual human societies come and go humanity seems to be better off in general today than ever before.

He also said that "the very idea of collapse is ideologically loaded" and offered a suggestion:

For a much more balanced approach to the issue of technological innovation and sustainability I recommend you take a look at the final chapter of Joseph Tainter's book "The Collapse of Complex Societies."

As it happens, I'm very familiar with Tainter's work, that book in particular. And since Tainter, a Utah State University anthropologist, was repeatedly cited by the authors, I already thought it would be good to get his thoughts. His first response was curt:

Overall I found the paper to be trivial and deeply flawed. It is amazing that anyone would take it seriously, but clearly some people do (at least in the media). You are correct that they cite my work a lot, but they seem not to have been influenced by it, or even to understand it. I suspect they were strongly influenced by the work of Peter Turchin—for which, please see the attached (short) review.

He then promised to send a more detailed response, which he emailed several days later. Here it is in full (emphasis mine)

It is interesting how collapse theories mirror broader societal issues. During the Cold War, we had theories ascribing collapse to elite mismanagement, class conflict, and peasant revolts. As global warming became a public issue, scholars of the past began to discover that ancient societies collapsed due to climate change. As we have become concerned about sustainability and resource use today, we have learned that ancient societies collapsed due to depletion of critical resources, such as soil and forests. Now that inequality and “the 1%” are topics of public discourse, we have this paper focusing largely on elite resource consumption. Models depend on the assumptions that go into them. Thus the first four pages of the paper are the part most worth discussing. The paper has many flaws. The first is that “collapse” is not defined, and the examples given conflate different processes and outcomes. Thus the authors are not even clear what topic they are addressing. Collapses have occurred among both hierarchical and non-hierarchical societies, and the authors even discuss the latter (although without understanding the implications for their thesis). Thus, although the authors purport to offer a universal model of collapse (involving elite consumption), their own discussion undercuts that argument. Contrary to the authors’ unsubstantiated assertion, there is no evidence that elite consumption caused ancient societies to collapse. The authors simply have no empirical basis for this assumption, and that point alone undercuts most of the paper. The authors assert that there is a “two-class structure of modern society,” and indeed their analysis depends on this being the case. The basis for this assertion comes from two papers published in obscure physics journals. That’s right, this assertion does not come from peer-review social science. It comes from journals that have no expertise in this topic, and whose audience is unqualified to evaluate the assertion critically. In other words, there is no empirical or substantiated theoretical basis for this paper’s model. In modeling, once one has established one’s assumptions and parameters, it is a simple matter to program the mathematics that will give the outcome one wants or expects. For this reason, models must be critically evaluated. Unfortunately, most readers are unable to evaluate a model’s assumptions. Instead, readers are impressed by equations and colored graphs, and assume thereby that a model mimics real processes and outcomes. That seems to be the case with this paper, and it represents the worst in modeling.

Others I queried, such as the Canadian scientist Vaclav Smil, and George Mason University's Mark Sagoff, noted the model's Limits to Growth echo. Sagoff was bluntly dismissive:

I skimmed the article yesterday and saw that it was the Club of Rome all over again -- the computer that cried wolf. I have no doubt that many empires fell as others rose. Now the average man lives better than the ancient emperor. We have seen creative destruction before and we will see it again. But what destroys improves. There is nothing here [in the paper] that was not presented in the 1960s and 1970s by Paul Ehrlich and other "Cassandras" as they called themselves. Their views, repeated in this [Guardian] article and study, have been completely discredited.

Sagoff ended on a down note:

I am sorry to have seen the paper you sent -- it is discouraging. Nobody learns anything or bothers to try.

So what do the authors of the study think of this harsh criticism? (I'm still waiting to hear back from additional social and environmental scientists. I'd like to know if others have a more charitable take on the paper). I've contacted two of the three co-authors repeatedly this week, asking to interview them about their paper--including how it's been characterized in the media and the critiques lodged in this space. But they have declined. They say they would rather wait to speak to the press until their paper is published in several weeks. If that's the case, then I think they will come to regret giving a Guardian writer an advance peek for a story ahead of publication. A second wave of media interest is unlikely to be triggered by the paper's official publication. Perhaps the authors are fine with that. One of them, Eugenia Kalnay, a University of Maryland atmospheric scientist, did convey to me, via email, her approval of the Guardian article:

Dr. Nafeez Ahmed wrote an excellent discussion based on a pre-publication draft of the paper.

Ahmed wrote an uncritical appraisal of the study. He didn't bother to inquire about the merits of the model or its results. If Kalnay and her colleagues would like to engage in actual discussion of their paper, I encourage them to visit this space. I will gladly post their responses.