In 1998, in an invited paper in the journal Ecosystems, Simon Levin made a case for the value of viewing ecosystems as complex adaptive systems, in particular to understand the relative roles of the environment and self-organisation in determining system properties. At the end of the paper, Levin proposed six questions that, according to him, “define a research agenda for the indefinite future”. Eighteen years after the paper was published, I asked Simon Levin about how he got interested in this topic, the making of this paper, and what we have learnt from viewing ecosystems as complex adaptive systems.
Citation: Levin, S. A. (1998). Ecosystems and the biosphere as complex adaptive systems. Ecosystems, 1(5), 431-436.
Date of interview: Questions sent by email on 16th November 2016; responses received by email on 24th November 2016.
Hari Sridhar: Correct me if I’m wrong, but from looking at your publication list it seems like your academic interest in ecosystem services and sustainability started in the 1990s. What got you interested in researching these topics?
Simon Levin: Well, I guess technically that is true, but only because that terminology only began to emerge in that decade. Gro Harlem Brundtland’s influential report on sustainable development came out in 1987, I took part in the Ecological Society of America’s committee (chaired by Jane Lubchenco) that produced a key report on the Sustainable Biosphere in 1991, and my involvement with the Beijer Institute in Stockholm heavily influenced my thinking on sustainability, and on ecosystem services, a concept that Gretchen Daily and others were developing at that time. But it was certainly concern for such issues that had enticed me from a career in mathematics into addressing such issues throughout my career.
HS: More specifically, what was your motivation to write this particular paper in 1998?
SL: My then-postdocs Gregg Hartvigsen and Ann Kinzig took the lead on editing a Special Issue, and asked me to write the piece. I saw it as a good opportunity to put some of my thoughts together, and to translate some of the insights I had gained especially from my involvement with the Santa Fe Institute (SFI) and colleagues there thinking about complex adaptive systems in different settings. I had already developed many of the ideas in my Ulam lectures to SFI in 1996, and they were more fully developed in my book, Fragile Dominion, which I was completing at the time. The book came out the next year.
HS: Today, terms such as ‘self-organization’, ‘criticality’ ‘power law distribution’ etc. are common in ecosystem research; but at the time you wrote this paper they were probably unheard of. Could you reflect on the impact this paper had on the development of this area of research?
SL: Well, that’s hard for me to say; I learned from so many others, and I am sure that their work was responsible for much of the impact. But there is no question that these have become core concepts throughout ecology and other fields in the intervening two decades.
HS: More specifically, do you have a sense of what this paper gets cited for, mostly?
SL: No, I haven’t attempted to survey that. But I am sure that it must be the notion that systems of interest, from our microbiotas to global society, are composed of large numbers of individual agents, whose individual actions give rise to emergent phenomena, including critical transitions, leading to conflicts between the interests and motivations of individuals and the good of the whole. Cancers arise within our bodies for this reason, and we need to avoid becoming cancers in the biosphere. So far, we have had limited success.
HS: Would you remember, approximately, how long the writing of this paper took, and when and where you did most of the writing?
SL: I am afraid I don’t remember that, since so many other things (like my book) were on the agenda at the same time. But I feel sure it was over a period of months; I generally tend to do constructive writing in the evenings, but I was writing my book in the mornings.
HS: You acknowledge “Steve Carpenter, Gregg Hartvigsen, John Holland, Ann Kinzig, Bob O’Neill and Brian Walker for helpful comments”. Could you tell us a little more about how you knew these people at that time and how they helped?
SL: As already mentioned, Gregg and Ann were postdocs with me. John Holland, more than anyone was responsible for the development of the concept of complex adaptive systems (CAS), had given the Ulam lectures before me, and was a close colleague at SFI. Bob O’Neill and Steve Carpenter are long-time ecological colleagues of mine, and have contributed a lot to the topic. I have known Bob 45 years, from my visits to Oak Ridge National Laboratory and his long visit to Cornell at my invitation. I was much influenced by my discussions with him, and from his development of hierarchical theories of ecosystems. I have known Steve Carpenter perhaps 30 years, and have been greatly influenced by his work on lake ecology. Steve also had direct involvement with my paper, as Editor of the journal Ecosystems. I have known Brian Walker’s work for a long time, but really got the opportunity to interact with him starting in the 1990s through the Beijer Institute, in Stockholm.
HS: Could you share with us why you decided to submit this paper to the journal Ecosystems? Did the paper have a relatively smooth ride through peer-review?
SL: It was basically an invited and commissioned paper, and I do not remember any obstacles at all.
HS: What kind of attention did this paper receive when it was published?
SL: I had no idea what the answer to this question was, so I looked it up on Google Scholar. It looks like the initial impact was muted, building up to citations in the 20s (which is modest, but okay), after 4 or 5 years. Then citations seem to have taken off. I have no idea why.
HS: Did writing this paper have any kind of direct impact on your career? How did it influence the future course of your research?
SL: Not that I can detect. I was writing lots of papers on related topics at that time, and the paper was more of a report on my thinking than an influence upon it.
HS: You identify three essential elements that are adequate to characterise any complex adaptive system. Today, 18 years after this paper was published, does your thinking on this remain the same?
SL: I had to go back to see what I had written; but, yes, those seem still to me to be the key characteristics. Of course, much of my work since has been on the consequences of those features, especially for the management of CAS. See for example
HS: You say that “Understanding how the population communicates with the ecosystem, much less the biosphere, represents a fundamental challenge for ecologists; these levels have traditionally been separated by a chasm that has also often, and regrettably, separated population and ecosystem scientists”. Could you reflect on whether and to what extent this situation has changed today?
SL: Actually, I am encouraged. In the past decade especially, from marine ecosystems to human societies, researchers have turned their attention to evolutionary perspectives on large systems, and especially in dealing with the problem of public goods.
HS: In concluding your paper you identify a set of six questions that “are likely to define a research agenda for the indefinite future”. Today, if you were asked to come up with a set of questions, would the list be different? Are there new questions to be added? Have some questions been sufficiently addressed so as to not be top priority now?
SL: Those six questions, further developed in my book, remain central. But I would put more emphasis today on the coupling of human and environmental systems.
HS: Have you ever read this paper after it was published? If yes, in what context?
SL: Not sure what “read” means. I go back and revisit it, as I did in preparing my responses to you. But if you mean “read” as presented in a seminar or meeting, the answer is “no,” but only because every lecture I give I like to think represents an incremental advance in my thinking at least, and so there is a (usually slow) evolution of ideas. Indeed, my current postdoc, George Hagstrom, and I have just submitted an invited sequel to Ecosystems, the other bookend to my original paper.
HS: Would you count this paper as a favorite, among all the papers you have written?
SL: Well, papers are like children: Difficult to choose a favourite. But, yes, I am pleased with how it turned out and the apparent influence it has had. And there is not much that I would change.
HS: What would you say to a student who is about to read this paper today? What should he or she take away from this paper written 18 years ago? Would you add any caveats?
SL: I would say to try to read the papers that cite it as well, and to trace its influence and what others have done to implement and improve the ideas.
Reflections on Papers Past 