HBES Newsletter Summer 2010
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H UMAN BE H AVIOR & EVOLUTION SOCIETY Summer-Fall 2010 Newsletter In This Issue View From the President’s Window MisMannered The Student Voice Featured Student Conference News HBES 2010 Competition Winners HBES 2011 Letters From the Editors Announcements Research Requests New Journals Members in the News Conferences The next HBES Conference will be held in Job Announcements Dr. Dev Singh Montepelier, France, June 30-July 3, 2011 View Interview MisMannered Students Carolyn Hodges Simeon & From the President’s Window Doug Kenrick Pete Richerson Kate Hanson Sobraske Our HBES president is Pete If you would like to conduct He’s back! After a long Current HBES Student Richerson, Distinguished an interview with one of hiatus, the HBES newsletter Representatives are Kate Professor in the Department the leading scholars in the is proud to announce the Hanson Sobraske and of Environmental Science field, please contact the return of the MisMannered Carolyn Hodges Simeon, and Policy at UC Davis. newsletter editor. collumn by Professor Doug both at UC Santa Barbara. In this edition, Professor Kenrick. (It’s aboot time!) We Richerson discusses the hope you enjoy the latest Read more... study of the contribution complexity in which Doug and diversity provides a of human new view of societies. the human mind. Read more... Read more... © Copyright HBES 2010 - All Rights Reserved | email: [email protected] | web: www.hbes.com View From the President’s Window | Pete Richerson Complexity and Diversity hen Rob Boyd and I started thinking trust the robotic “thinking” of computers. about the evolution of human behavior Even if we grant that the reductionist argument is W back in the 1970s, we decided that the too simplistic, or just plain wrong, the second two complexity and diversity of human societies and arguments remain valid. Besides, if complex realistic cultures was one of the main challenges. For those models are ultimately useful, they will have to be built of us with a background in biology—I came from up from simpler components. entomology and ecology—an appreciation for the complexity of organisms and their diversity was part The philosopher of biology Bill Wimsatt argued for of the atmosphere. Entomologists are fond of the a toolkit view of theory in complex diverse fields. reply that the great early 20th Century evolutionist Evolutionists and ecologists make many models for JBS Haldane is reputed to have given to a clergyman diverse problems. In the face of particular problems, who asked him what he had learned of the Creator biologists rummage through their toolkit for by studying his work: “He must have an inordinate appropriate models likely to explain the case at hand. fondness for beetles.” Beetles are the most diverse It often turns out that the behavior of the system they order of the most diverse class of animals, the insects. are studying is dominated by a manageable number Regarding complexity, Haldane was equally pithy: of processes. Its behavior can be understood and “My suspicion is that the world is not only queerer predicted and understand with a relatively simple than we suppose, but queerer than we can suppose.” model. Of course, there are no guarantees, but as their toolkit expands biologists can hope to explain more One of the paradoxes of ecology and evolutionary and more phenomena. The toolkit itself becomes a biology was, and still is, that theoretical biologists were highly organized system of submodels with known fond of creating simple models the world. Doesn’t a properties so that the analyst can readily guess complex real world suggest that our thought about that, for example, a frequency dependent model of that world have to be complex? Biological theorists selection is likely to apply if strategic interactions made three different kinds of arguments for applying between individuals are important. simple models to complex, diverse phenomena: Humans are certainly diverse, complex organisms. 1) Surface diversity and complexity concealed a lot of Through culture, people adapt to their environments simplicity that proper theory accurately depicts. This in historically contingent ways leading cultures position is often called reductionism. to become diverse. In ecological terms humans 2) Complex models are not worth the effort it takes resemble an adaptive radiation of species rather than to construct them. This used to be inescapable, but a single species. The diversity of individual behavior with advent of digital computers that could manage within complex societies is comparable to that of complexity it became less true. Ecologists could the diversity of tissues and organs that make up imagine making quite complex models and many did. multicellular organisms. But in practice complex models had only slightly or no Many anthropologists and historians celebrate the greater predictive power than rather simpler models. complexity and diversity of human life much as natural 3) Simple models are hard enough to understand and historians do biological complexity and diversity. complex ones are impossible. Science is about using Other social scientists take a more reductionist view, the human mind to think about the world. Since there arguing that much of the complexity and diversity of are limits to our ability to understand complexity we human behavior is superficial. Most famously, Noam either have to use rather simple models or to blindly Chomsky argued that most of linguistic diversity The View From the President’s Window (cont.) was superficial. Underneath the surface, languages theoretical footing. were underlain by a few innate principles each with Economists, policy analysts and the like are fitting a relatively few parameter settings that differed from models to human societies all the time, trying to language to language. Perhaps much apparent human understand, trying to make sense of the complexity complexity and diversity will collapse in this way. and diversity based on very little data – trying to predict For Rob Boyd and I, the issue of whether human outcomes. We want simple models but we want to complexity and diversity turned out to be superficial choose the models that account for the maximum or deep didn’t matter in the first instance. Simple amount of the available data. Models that “underfit” models of cultural evolution would be useful no leave real information in our data unused. As Nassim matter how the reductionism issue came out. So we Taleb explained in his book Black Swan, risk analysts and others built up a toolkit of simple models that inspired by too-simple models “underfit” the problem typically have variables and parameters that are of uncertainty contributed to recent economic policy open to interpretation. People are biased in favor of disasters. They ignored the fact that real economic adapting some cultural variants as opposed to others time series data had more extreme values than in such models. Are the kinds of biases few or many? predicted by the too-simple normal distribution, Are the bias parameters controlled by genes, culture, leading them to create masses of securities that were or a mix of the two? Are individuals or cultures far riskier than they believed them to be. variable with respect to the biases they apply or is By the same token, we don’t want to accept a simple there a lot of inter-individual and cross-population genetic explanation for a bit of human behavior if similarity? The models themselves were silent about culture also plays an important role, or vice-versa. The such empirical issues. attempt of linguists to find a compact set of principles After decades of studying ecosystems, ecologists and parameters underlying the superficial diversity and evolutionists still find that nature being “queerer of languages failed as Fredrick Newmeyer, one who than we can suppose” resonates. In my guise as an tried, explained to me recently. Languages have a lot ecologist, I conducted long term studies of three lakes, of real diversity. Joe Henrich, Richard Nisbett and all of which turned up major surprises even after years their colleagues have used experimental methods to of study. As the applied ecologists Kenneth Burnham buttress classical ethnographic accounts of cultural and David Anderson put it in their extremely influential diversity. At the same time increasingly abundant 2002 statistics text, Model selection and multimodel gene sequence data is telling an increasingly complex inference: a practical information-theoretic approach story of rapid organic evolution in the late Pleistocene (10,000+ sites according to Google Scholar) put it and early Holocene as modern humans spread out of “we believe that ‘truth’ (full reality) in the biological Africa and adopted agricultural subsistence. sciences has essentially infinite dimension.” At the On the other hand, modern statistical packages same time, the data available about the complex real tempt us to plug lots of explanatory variables into a world is always strictly limited. In practice, our data multiple regression model to try to explain our data. limits us to only a glimpse of reality. The statistical But if we’re not careful, we’ll fit the noise as well as theory Burnham and Anderson describe is designed the information in the data. If we “overfit” our data, to help us choose models that extract all of the any truth it contains will be confounded with error. information in our data (avoid “underfitting”) while not Chocolate consumption will appear to cause cancer imagining that our data contains more information in one study and protect against it in the next, even than it does (avoid “overfitting”). though we have no real grounds for thinking that Scientists have long worried about the problems of chocolate has much to do with cancer one way or overfitting and underfitting data. Consider Einstein’s the other. famous aphorism “models should be as simple Information theoretic methods have a neat twist that as possible, but no simpler.” Information theoretic reflects the fundamental uncertainty of the scientific statisticians aim to put Einstein’s intuition on a sound enterprise.