The Anthropocene as the Physical Record of Social-Ecological Systems

Discussion paper presented in the symposium “Archaeological Perspectives on the Anthropocene,” at the 2018 Society for American Archaeology meetings in Washington DC.

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Slide Notes:

1. As I walk around the SAA meetings these days, I see a general trend towards particularism. There has been an uptick in sessions related to increasingly detailed interrogation of artifacts (e.g., down to the molecular level) and by a veritable plethora of hyper-regionalized sessions on specific aspects of specific cases or specific sites. While it is heartening in some sense to witness the level of detail we can now get from ever-more-fine-grained analysis of the specifics of the archaeological record, seeing all this, I can’t help but feel that I am somehow a “bad” archaeologist because I’m not interested in doing any of that. This is because, over the years, my attention has strayed farther and farther away from the particulars and details of archaeological analysis to the point where issues of material culture, style and form, specifics of culture histories, etc., are no longer what drive my interest in the discipline, or our subject matter. It’s not that I don’t think these are interesting or important things; they are. And it’s not that I don’t think we should be doing any of this; we should. Instead, it is mainly that I think there is a more important overarching question that our discipline has been skirting for years: how can we take the material of the past and use it to help figure out what we should do in the future? For me, all of the classic debates in archaeology – about domestication, rise of social complexity, etc. – although interesting on their own, are only really important in the context of that larger question. If our ever-increasingly detailed analyses of material culture don’t feed into an increased understanding of the dynamics human systems, then I simply can’t get behind the added time and expense of doing all that. And ultimately, it’s within this larger question that I think we need to situate archaeology in regards to the Anthropocene debate as well.

2. First, a little about me and what I do: I look at landscapes, and I consider how they got the way they are over very long timespans. Here’s a few nice panoramas from three of my field areas: Northern Jordan, Southeast Kazakhstan, and Southern Italy. In many ways, these three landscape exemplify the Anthropocene. People and their agents (herd animals, cereal crops) made these landscapes, and there is a physical record of that modification that we can go and find and analyze. But, while we know they are the result of the same general processes (farming of cereals and herding of ungulates, for the most part), these landscapes are not the same. Why are they so different? Why do we not have a homogenized landscape of agropastoralism around the world?

3. And here’s the thing: I go for a few weeks in the summertime, I walk around on these landscapes, I take a few samples, record some data, and perhaps dig a few holes here and there. From that limited window into the past, I am able to obtain a small handful of clues about the anthropogenic processes that perhaps helped to form these landscapes over time. And here you can see some of those specific tidbits of information I’ve gathered about the timing of some anthropogenic events that helped shape these three specific landscapes. Which one of these is “the signature” of when we can say “it’s the Anthropocene?” Is it 20,000 years ago in Northern Jordan, where I’ve found evidence of large-scale human use of fire to modify landscapes? Is it 2500 years ago in Iron-age Kazakhstan where we have evidence of human manipulation of flowing water that fundamentally changes depositional processes in the region? Is it 100 years ago in southern Italy where we are showing how people were motivated by opening global markets for cash crops (bergamot) to re-colonize long-abandoned coastal valleys and thereby fundamentally modify water flow and erosion processes by formalizing these commercial agricultural terraces with stone walls? Add to this the kinds of evidence that have been presented today, from the Neolithization of Mediterranean islands, to the creation of the Sahara, to the Yellow River, to the anthropogenic Amazon, to the overfishing of Red Abalone on the Channel Islands. The answer, in my mind, is that it is simultaneously all of these and yet none of these. Let me explain this dissatisfying answer.

4. The Anthropocene is simply, and only, the physical proxy record of human and natural dynamics which are now gone, and, thus, are unknowable. It is those long-gone dynamics that we are interested in, however, and we must try to reconstruct them from a very fragmented and incomplete record. In many ways, therefore, the search for a “Golden Spike” is a red herring that is keeping us from getting at those other important questions that Nicole was talking about earlier. the “whys” and the “hows” rather than the “whats” and the “whens.” It’s the models that we will build and test against our archaeological data of the Anthropocene that are going to be our contribution to those questions, not necessarily the specifics of the physical record itself. However, when we go about doing this, we need to keep in mind some important characteristics of SES, and we have to think about how we are going to do the modeling.

5. We have to keep processes of scale foremost in our mind when we study the Anthropocene. Searches for the global Golden Spike will miss the small processes, and archaeology’s ever deeper dive into the minute details of artifacts will miss the larger scales. We must continue gathering and assessing data at all of these scales, but it is the the cross-scale interconnections are likely key to Anthropocene SES processes.

6. It’s therefore vital that we improve our understanding about the nature and consequences of couplings and feedbacks in SES. In particular, we need to understand couplings between human and natural components, and how these can lead to runaway effects over time. At the same time, it’s important to remember that we can learn from stories of both failure and success in the past. For example what Michael Heckenberger was telling us about his Amazon case of converting forest to other kinds of forest and protection against fire is a great story of success that we can (and clearly are) learning from.

7. And one of the results of all this feedback and coupling is structural change in SES. How do the components and interconnections in SES rearrange or change over time as a result of all those feedbacks? We know that the temporal (and spatial) dynamics of SES can result in non-linear changes in some cases (and linear changes in others), and in certain cases, SES exhibit abrupt change where the system fundamentally reorganizes to a different stable state that is as “locked in” as the previous state was. Really, one of the reasons why we should care about the Anthropocene is that we don’t want to have to go through one of these abrupt major changes in our current global SES. The earth will be fine (probably), but at our human time scale, this will be very disruptive and damaging. We probably don’t want to be the generation that goes through that, and we probably don’t want our future generations to be vulnerable to this as well.

8. I want to, at this point, reiterate that we cannot know exactly what will happen. But, we can at least get some good ideas about what realistically might happen. Simulation models, informed by archaeological data and anthropological theory, can really help us do this. They will not “predict” the future, in the same way that they will not “reconstruct” the past. They will, however, let us understand how we can engineer our future global SES to be the way we want it to be (hopefully, more stable, more productive, more predictable). If you are uncomfortable with the idea that we should be engineering the Earth System, then I’m sorry, but it’s too late. We are already doing it. Except that we are doing it blinfolded and purposefully oblivious to the fact that we are doing so, let alone to the consequences that might emerge.

9. The specifics of any particular case study are important for reconstructing one particular time series of Anthropocene dynamics. We cannot, however, pretend that knowing the outplay of one (or even a handful) of Anthropocene stories will be enough for us to tackle those important questions about where the Anthropocene will go in the future. We have to be building models with these data. Models that have the capacity to suggest some novel kinds of Anthropocene dynamics that are possible, even if they have never been observed (yet, as Todd just said). I will here make the plea that simulation modeling will be an important method to achieve this.

10. And this is why we need to emphasize archaeology as the social science of the long term. We must do our part, otherwise, this is all going to play out without us, and in spite of us. There is a large community of researchers who build global models to influence policy. In particular, the Integrated Earth System Models (iESM, or Integrated Assessment Models) are being used around the world to set policies. These models are mostly natural science models. The very moderate social science aspects of the current iESM’s are made by economists, and basically map GDP to land-use. Let me reiterate that these models are used to make policy. Do we really want that approach to be the sole social-science input into these models? Over the last couple of years, I have been getting involved in these iESM communities. Thus far, there have only been a handful of archaeologists that have been doing this, but I really think that it is a venue that we need to be much more involved in. Yet, it is exactly the nuanced, yet long-term understanding of social processes that archaeology offers that best fits the goals of doing iESM’s. I hope more of you will consider joining.