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  • Collapsing reviews

    Fri, 2010-02-19 07:30 -- John Hawks

    Nature this week gave Jared Diamond the chance to review two books about archaeology and "collapse" -- The Cambridge Companion to the Aegean Bronze Age (which he liked), and Questioning Collapse: Human Resilience, Ecological Vulnerability, and the Aftermath of Empire (which he didn't like).

    Diamond's book, Collapse, has been a target of criticism by anthropologists since it was released. I noted some of these critiques in 2005. So it's interesting to see how Diamond responds to McAnany and Yoffee's Questioning Collapse. Much comes down to how different people define "collapse".

    It makes no sense to me to redefine as heart-warmingly resilient a society in which everyone ends up dead, or in which most of the population vanishes, or that loses writing, state government and great art for centuries. As Questioning Collapse shows, that naively optimistic redefinition inevitably forces one to distort history and to avoid trying to explain what really happened. Even when many people do survive and eventually reestablish a populous complex society, the initial decline is sufficiently important to warrant being honestly called a collapse and studied further. We today, who face similar problems and could face similar fates, will not be consoled by the thought that our grandchildren might exhibit resilience.

    Well, a society is sure to lose its monumental architecture and indigenous writing systems when everybody dies, but it might lose them for other reasons. If people tire of a bloodthirsty death cult (like Congress), should we mourn its demise? When archaeologists can document a "collapse" of residential, agricultural, or ceremonial systems, the demographic impact might well have been bad, but it's rarely obviously so. And the connection between these "collapses" and political, economic, or ecological conditions -- connections that are essential to Diamond's thesis about collapse -- tend to resist simplistic causal explanations.

    I looked at Savage Minds, hoping they'd picked up on this sentence from Diamond's review:

    Another essay describes a New Guinean man named Yali, giving a lengthy reinterpretation of his views about the European colonization of New Guinea in the light of the experiences of another man with the same name — not realizing that the two Yalis were different people, 40 years apart in age and with dissimilar life stories and opinions.

    Diamond himself doesn't explain the significance of his point: "Yali's question" ("Why do you whites have so much cargo?") appears a central organizing element of Diamond's Guns Germs and Steel. It's an underlying agenda that isn't transparent to most readers of the review.

    I think that the reality is somewhere in between. Human societies have failed for all kinds of reasons. Many of these I would be hard-pressed to describe as "tragic" -- much of the cultural production in complex societies comes from elites, most of which have been oppressive. Starvation, subfertility, and disease have been depressingly common, but I don't think most such "collapses" could have been prevented by better decision-making.

    UPDATE (2010-03-04): Frequent Diamond watchdog Stinky Journalism is on the story.

    References:

    Diamond J. 2010. Two views of collapse. Nature 463:880-881. doi:10.1038/463880a

    Tags: 
    archaeology
    history
    complex societies
    Jared Diamond

  • Defenestrating deforestation

    Sun, 2010-01-10 07:30 -- John Hawks

    Lots of people have written about the collapse of the ancient Maya, often as some kind of "lesson" about how present-day society needs to change for its own survival. A recent theme, pushed by Jared Diamond in particular, but also others, has been that the Maya failed to manage natural resources sustainably. Their political structure couldn't deal with the growth of their population, and short-term decision-making led to ecological collapse.

    Well, it's easy enough to propose such a sweeping hypothesis, but devilishly hard to test it. And so it's easy to forget that it is just a hypothesis.

    In the early bin at PNAS, McNeil and colleagues report on a test of the hypothesis for one locality, Copan, Honduras:

    Archaeologists have proposed diverse hypotheses to explain the collapse of the southern Maya lowland cities between the 8th and 10th centuries A.D. Although it generally is believed that no single factor was responsible, a commonly accepted cause is environmental degradation as a product of large-scale deforestation. To date, the most compelling scientific evidence used to support this hypothesis comes from the archaeological site of Copan, Honduras, where the analysis of a sediment core suggested a dramatic increase in forest clearance in the Late Classic period (A.D. 600–900). By contrast, in the work presented here, the authors’ analysis of a longer sediment core demonstrates that forest cover increased from A.D. 400 to A.D. 900, with arboreal pollen accounting for 59.8–71.0% of the pollen assemblage by approximately A.D. 780–980. The highest levels of deforestation are found about 900 B.C. when, at its peak, herb pollen made up 89.8% of the assemblage. A second, although less pronounced, period of elevated deforestation peaked at approximately A.D. 400 when herb pollen reached 65.3% of the assemblage. The first deforestation event likely coincided with the widespread adoption of agriculture, a pattern found elsewhere in Mesoamerica. The second period of forest clearance probably was associated with the incursion of Maya speakers into the Copan Valley and their subsequent construction of the earliest levels of the Copan Acropolis. These results refute the former hypothesis that the ancient Maya responded to their increasingly large urban population by exhausting, rather than conserving, natural resources.

    I admire this kind of close empirical work -- identifying pollen in sediment cores may not be glamorous, but it's maybe the best way we have to document human impact on these ecologies.

    References:

    McNeil CL, Burney DA, Burney LP. 2009. Evidence disputing deforestation as the cause for the collapse of the ancient Maya polity of Copan, Honduras. Proc Nat Acad Sci USA (online early). doi:10.1073/pnas.0904760107

    Tags: 
    climate
    complex societies
    climate change
    Maya
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