Why worry about the maturing of a science ?

Peter Kareiva

kareivap@zoology.washington.edu

Romanticizing the past and missing the point of the future

I can remember the "good old days" of ecology, and they were not so good. And when I consider what is going on currently in ecology, I see extraordinary advances and creativity, albeit not along the lines that were hoped for during what I consider to be ecology's sophomoric phase. I want to make three points:

1.) the golden era of ecology that Jim refers to was actually a naive (but necessary) step towards a more mature science

2.) it is easy to come up with recent advances in ecology every bit as exciting as anything from between 1955 and 1975, and much more useful

3.) the dichotomy between reductionism and synthetic science (or the science of "complexity") is misleading and ill-posed.

The "Golden Era" or fond memories of adolescence?

As a graduate student at the end of the seventies, I was forced to read many of the papers from between 1955 and 1975 that Jim probably fondly remembers as pathbreaking. I am sure I remember these papers differently than he does -- I found them lacking in mechanism, testability, and rigor. They were like the dreams and wishes of a teenager --- wouldn't it be cool if measuring where warblers fed in trees for a few hours of total observation time informed us in a serious way about warbler population interactions and dynamics? Sure, there were lots of ideas, but what exactly did ecology get right? What non-obvious predictions were made and vindicated? Certainly there were 20 or more studies that changed the course of the discipline, but what type of change was it? I think of ecology's shift during that golden era as something akin to the rampant biological and social upheaval that goes on during an adolescent's teen-age years. But "growing up" should not be equated with a loss of intellectual firepower -- instead it reflects a sharpening of vision and focus -- and that is exactly what has happened in ecology. Let's honestly go back to those twenty years of ecology and review the type of research that dominated our journals. Niche descriptions and studies of niche overlap prevailed. Comparisons between models and data were anecdotal, and the type of species interactions that were studied was unduly biased towards competition. Genetic architecture, structured populations, spatial processes, an appreciation of the subtle ways environmental variability alters species interactions, nonequilbrium dynamics and many more ideas we now take for granted were all woefully neglected. Patterns of diversity, patterns of niche overlap, patterns of plant spacing, patterns of body size -- patterns were all the rage. But where was dynamics?

We are asking better questions with clearer thinking and more sophisticated methods

In lieu of an emphasis on "patterns", modern ecology is in fact concerned with dynamics and processes. This shift changes the research agenda and the types of questions researchers find interesting. Among the many exciting issues to be illuminated in the last twenty years are the generation of spatial patterning in homogenous environments because of dispersal and local nonlinearities, the importance of age or stage structure at altering dynamics, the interplay of genetics and ecology in controlling species interactions, the many sources of chaos, the role of environmental variability in promoting or preventing coexistence (depending on how that variability influences a species' demography), the role of trophic cascades in ecosystem dynamics, the threat of exotic species as wholesale community perturbations, the central importance of tradeoffs as facilitators of biodiversity, and dozens more. Instead of asking why there are more species in the tropics than in the temperate zone, ecologists now seek to understand what processes maintain diversity within particular systems, and what might be the "function" of biodiversity. Instead of asking if patterns of niche overlap are random, ecologists now seek to predict the vulnerability of species to habitat degradation as a result of habitat usage. Instead of endless calculations aimed at identifying equilibrium population densities, theoreticians now appreciate the rich spectrum of population dynamics that never give a glimmer of equilibrium behavior. Ecology is routinely used to mitigate threats to endangered species, to identify prime portions of the landscape in need of protection, to restore damaged ecosystems, to suggest approaches for the control of exotic invaders, to provide methods for risk analysis pertaining to genetically engineered crops, and much more. Where was ecology in the sixties when environmental degradation and the loss of biodiversity was already well underway?

The so-called antagonism between reductionist science and the synthetic science of complexity is simplistic

Of course reductionism by itself is inadequate. But very few ecologists I know retreat totally under the blanket of reductionism. Indeed, I wonder if what Jim Brown is calling reductionism isn't really just a rejection of the emphasis on patterns as opposed to dynamics. Reductionism does not imply that dynamic processes are predictable in a simple manner. A reductionist could well-appreciate the chaotic dynamics of nonlinear systems, and seek to understand what aspects of the environment influenced the tendency of a system to move towards chaos. In fact I see no connection between the fact that systems are complex and the relative merits of reductionist science. Why should we worry about some imagined narrowness, when more ecologists than ever before are making connections with economics, with risk analysis, with land management, and with environmental policy ? Jim points out that medicine and the treatment of immensely complicated and unpredictable human bodies must recognize uncertainty. I agree. But this has nothing to do with reductionism. The mistake Jim makes is to think that a reductionist cannot deal with uncertainty, and is wedded to trying to predict specific population densities. But this is simply not the case. Medicine is an enormously successful reductionist enterprise, and one mature enough to not worry about predicting when someone might die -- instead it seeks to understand the causes of death.

Jim dreams of universal laws that will help us meet our environmental challenges. I think we have all the universal laws we need in ecology. Our future advances will not be concerned with universal laws, but instead with universal approaches to tackling particular problems, and with general theoretical insights about the surprises that may ambush us if we think too narrowly. I am much more worried that the pinings of senior scientists for some long-past glorified era will distract us from our real problems, than I am worried about the lack of fundamental progress in ecology. NCEAS has two missions: (i) the synthesis of data and ideas that yield new insights, and (ii) the application of ecological theory to realworld problems. If NCEAS truly attempts to address real problems, I am convinced theoretical ecology will be pulled along and that original synthesis will emerge (recall what happened in theoretical physics at Los Alamos towards the end of World War II). The NCEAS need not worry about being cosmic -- it simply needs to ensure that imaginative scientists are brought together to apply theory to our environmental problems and to exchange ideas across disciplinary areas. I doubt that our current generation of graduate students is upset by the absence of universal laws in ecology, and I am one of those people who thinks we should always turn towards our youth for vision (and our elders for moderation). The type of ecology Jim hopes to resurrect has had its day, and the time is now ripe for a different type of ecology, a sophisticated, frustrating, but useful science.

Peter Kareiva is a Professor of Zoology at the University of Washington, Seattle, WA 98195. The ideas expressed above were developed as a result of reading Jim Brown's essay while teaching conservation biology at the Mountain Lake Biological Station in Virginia.

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