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Thursday
Oct222009

5 Questions in Evolutionary Theory: Interviews

1. Why were you initially drawn to discussions and research in evolutionary theory (or evolutionary aspects of your field)?

My grandfather was a self-educated socialist who believed that every worker should know at least evolution, cosmology, and history. His views of evolution were Lamarckian, and that primed me to be fascinated by Lysenko’s critique of genetics that seemed so dynamic compared to the “bean bag genetics” we got in high school.  At the same time I met Marxist dialectics through the works of Haldane, Bernal, Needham, and Oparin. I dreamed interactions, connectivity, contradiction, wholeness and developed an aesthetic of complexity. In college I tried some Lysenkoist experiments (graft hybridization of tomatoes, the effects of pollen mixtures in corn) that turned out inconclusive for technical reasons. Years later, while a farmer in Puerto Rico, I rejected Lysenko because he located the origin of new species in individual development where I saw it as a population-level process. I found that Waddington and Schmalhausen had a better view of the feedback between individual development and ecology with the population and community levels. I decided that perhaps I could contribute something to science, and applied for graduate school.

2. What does your work reveal about biological evolution (or evolutionary aspects of your field) that other academics, citizens, philosophers or biologists typically fail to appreciate?

Most of the main elements of my work are now part of the common sense of the field:

  • The overlap of evolutionary and ecological time so that natural selection has to be seen in the context of changing conditions.
  • Species adapt not only to specific features of the environment but also its pattern of variation in space and time, to uncertainty, patchiness, etc. This made adaptive strategy a central object of research.Faced with opposing demands, a species may adapt to some compromise phenotype, adapt to one demand while ignoring the other, or adopt a mixed strategy. This was expressed through the fitness set.
  • Organisms select, transform, transduce, define and respond to their own environments. The organism and its environment evolve together.
  • The response of a species to changing conditions takes place within communities of species so that an environmental impact on any one member percolates through the network of interactions is damped along some pathways, amplified along others, even inverted. The responses of interacting species can be studied through the community matrix, signed digraphs (loop analysis) and time averaging.
  • This lead into an explicit investigation of the strategies of modelling, especially qualitative mathematics to determine what we can get away with not knowing and still understand a system. From this perspective the task of mathematics is to educate the intuition so that the obscure becomes obvious and even trivial.
  • Evolution and population dynamics proceed at multiple levels that may conflict. The direct impact of the environment may push the phenotype in one direction while natural selection moves it in another. For instance, along a gradient from the coastal desert to the rainforest in Puerto Rico, Drosophila melanogaster individuals are about the same size. Higher coastal temperatures make them smaller, but the selective pressure of desiccation makes them genetically bigger. In other cases, selection and direct impact push in the same direction so that species differ in nature in the same direction as they differ under controlled conditions, but more so. The meta-population concept expresses the possible opposing processes at group and mendelian levels of selection.
  • Biogeography is the result of the interaction among colonization, extinction, and speciation. Robert MacArthur, E.O. Wilson and I had planned a division of labor in which they would ask “how many species are there on islands?” while I would ask, “How many islands does a species occupy?” It was intended that both approaches would converge in a continental biogeography. Although this program was thwarted by Robert’s early death and disagreements with Ed over socio-biology, it remains a valid strategy.

3. What, if any, practical and/or social-political and/or moral obligations follow from your work on evolution?

  • Anti-reductionism. No one level is more “fundamental” than any other. If gene action may determine which molecules are synthesized, the organism’s conditions can determine which genes are active, the ecology determines those conditions, and past history gives us the genes that are there. Further, society is the evolving context for social change and individual’s conditions. Social arrangements are fluid, and it is a mistake to attribute current, even widespread, phenomena to some fixed “human nature”. Once social conditions are seen as co-variable with ecological processes, we can ask the question: how do we build a society where it makes sense to be kind?
  • The state of our science, with its pattern of powerful insights in the small and irrationality at the level of the enterprise as a whole, is also a social product not dictated by nature. It has a dual nature as the unfolding of human understanding and as the evolving product of a knowledge industry much conditioned by its owners. The examination of the social context of scientific priorities and beliefs is a necessary part of making scientific decisions. Thus our group criticized the expectation that infectious disease had been defeated in principle. The idea of the epidemiological transition was a major error, caused by several kinds of narrowness: extrapolation from short span of history and limited geographic range, limitation to a single species, ignoring of evolution and ecology, and the passive acceptance of “development” as a unilinear process in which the “less developed” recapitulate the history of the more developed. The green revolution was another failure due to narrowness and a static acceptance of boundary conditions of a market economy (capitalism). It promoted an agricultural evolution from labor to capital intensive, small scale to large scale, heterogeneity to homogeneity, dependence on nature to domination of nature, and ignored issues of land reform in favour of market fundamentalism. But it was caught by surprise: pesticides created pests, mechanization degraded the soil, plant breeding reduced genetic resources, technology increased class inequalkity in the countryside. Our alternative approach toward an ecological agriculture promoted knowledge-intensive agriculture with a mosaic of land uses and the nudging of natural systems of soil fertility and pest management, all in the context of a land reform.This approach to agriculture contributed to the Cuban adoption of ecological and organic farming.
  • Waddingtonian homeorhesis makes the study of vulnerability central to understanding health. From this perspective, the observed variance in a population is a result of the extent to which people’s physiology is perturbed compared to the restoring forces (homeostasis) available. In poor, marginalized communities there is a more rapid erosion of homeostasis and also increased perturbation. In these conditions, small differences in individual circumstances have big effects. The question is therefore not why some poor people do well and others badly (the conservative, individualistic question), but what are the conditions that increase vulnerability. It therefore favors collective approaches to misery.

4. What do you see as the most interesting criticism against your position in the biological or philosophical discussion of evolution?

  • My early work was hyper-selectionist. It focused on the question, what would the optimum condition be although I claimed only that species in nature would be expected to differ in the same direction as their optima. But I failed to consider processes such as: hitch-hiker genes carried along by selection at linked loci; epistatic constraints; slow gene frequency change near an adaptive minimum; random fixation of genes; multiple equilibria and selection toward extinction within communities.
  • It is often asserted that modern computation makes it unnecessary to simplify or to engage in clever analytic tricks for solving equations so that qualitative methods are obsolete. However numerical methods require vast amounts of data. They are expensive, and make generous funding necessary. They are good for extrapolation but less so for understanding. What is needed is a good combination of qualitative and quantitative mathematical methods.

5. With respect to present and future inquiry, how can the most important problems concerning evolutionary theory (or evolutionary aspects of your field) be identified and explored?

  • Look for connections between phenomena that are usually kept separate by disciplinary, institutional, and theoretical barriers. The mapping between genotype and phenotype is being enriched by dynamic systems theory which shows that small changes in parameters can produce major changes in outcome. The demonstration of a role for symbiosis in evolution places in the agenda the conditions under which alien organisms can survive and be incorporated into hosts as part of the genome.
  • Consider questions of what hasn’t evolved. Why are there no co-enzymes that require lead, cadmium or aluminum? Why have no organisms evolved wheels? Can we experimentally select population to transcend the adaptive niches of their genera? (Once, long ago, Leigh Van Valen and I proposed a long term project in macro-evolution, selecting Drosophila to be aquatic (outside the family Drosophilidae but possible for insects. It remained in the bin of bright ideas, but Bruce Wallace picked it up and managed to select for aquatic larvae.)
  • Map “niche space”, the ease of transitions between one and another mode of life. Some groups probe the limits of their adaptive zone repeatedly and spill over into other ways of life while other groups seem to be caught in adaptive prisons and show only limited ranges. In agricultural practice, natural enemies are often introduced to control pests. But we do not select to adapt already present parasitoids to adapt to new hosts. In epidemiology, the age of antibiotics may turn out to be a rather brief successional stage in our relations with the microbial world. We are running out of new ones that are sufficiently novel to thwart the parasites. But what if we used an evolutionary strategy? Suppose we treated severe cases of an infection curatively and mild cases palliatively. Could we select pathogens for reduced virulence and eventually toward commensalism?

More abstractly, we could apply dialectical principles to ask questions:

  • i. The truth is the whole. A problem has to be posed big enough for an answer to fit.It is easier to start too big and justify reducing the problem than to begin too narrowly and be dragged kicking and screaming to see the bigger picture.
  • ii. There will always be surprises. We have to be able to ask, “But what if we’re wrong?”  And in particular to question the certainties of science. Students should be able to speculate on how might the second law of thermodynamics be overthrown, not to overthrow it but to emphasize that all theories have half-lives.While the main thrust of research has to be along lines that are judged to be plausible, there is the problem that the judges are the people who created the field as it is and are less likely to appreciate major departures. Therefore I announce the as yet unfunded Levins grants consisting of a hammock and a few cases of beer, awarded to promising investigators on the hope that they will come up with something interesting.
  • iii. Things are more connected than we expect. Therefore it is a good exercise to ask students for possible connections between seemingly unrelated phenomena. How does the ability of wheat plants to take up nitrogen affect the economic independence of women?
  • iv. Things are the way they are because they got that way. They haven’t always been so, are not everywhere so, need not be so forever. This divides into the two questions, why are things the way they are instead of a little bit different, and why are things the way they are instead of very different. The first is the question of homeostasis, self-regulation. The second is the question of evolution, development, and history.
  • v. A “thing” is a snapshot of a process, preserved by a temporary balance of opposing forces long enough to earn a name.
  • vi. Apply all these tools to ourselves and the state of our field. The “scientific method” works pretty well to avoid idiosynchratic error: wash your glassware; don’t divide by zero; every experiment needs a control; the patients and the administrator of pills should not know who gets the placebo. But it does little to correct the shared biases of our field, the “truths” which seem self-evident are never questioned. In order to escape the determination by our own narrow communities, we have to step outside. “Outside might mean a different discipline, the same discipline in a different culture, or non-academic communities such as farmers or activist environmental groups. We can never be free of having a point of view but we can become more aware of our biases.

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