Complexity Digest 2012.05

2012/03/03

Editor-in-Chief: Carlos Gershenson
Founding Editor: Gottfried Mayer

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Content

  1. Alan Turing at 100, Nature
  2. Early Warning Signals for Critical Transitions: A Generalized Modeling Approach, PLoS Comput Biol
  3. Stability criteria for complex ecosystems, Nature
  4. A measure of individual role in collective dynamics, Scientific Reports
  5. Peter Diamandis: Abundance is our future, TED.com
    1. Vijay Kumar: Robots that fly ... and cooperate, TED.com
    2. Shlomo Benartzi: Saving for tomorrow, tomorrow, TED.com
  6. Modeling the Adoption of Innovations in the Presence of Geographic and Media Influences, PLoS ONE
  7. The Robustness and Restoration of a Network of Ecological Networks, Science
  8. The case for open computer programs, Nature
  9. Encouraging Behavioral Diversity in Evolutionary Robotics: An Empirical Study, Evolutionary Computation
  10. Fly out-smarts man, arXiv
    1. Spread of Social Information and Dynamics of Social Transmission within Drosophila Groups, Current Biology
  11. Econophysics of a religious cult: the Antoinists in Belgium [1920-2000], arXiv
  12. Identification of the Social and Cognitive Processes Underlying Human Cumulative Culture, Science
  13. Evolution of the Earliest Horses Driven by Climate Change in the Paleocene-Eocene Thermal Maximum, Science
  14. Collapse of Classic Maya Civilization Related to Modest Reduction in Precipitation, Science
  15. Interaction Histories and Short Term Memory: Enactive Development of Turn-taking Behaviors in a Childlike Humanoid Robot, arXiv
  16. State concentration measure of quickness in Kauffman-type networks, arXiv
  17. Quantitative analyses of empirical fitness landscapes, arXiv
  18. Complexity of networks II: The set complexity of edge-colored graphs, Complexity
  19. Book Announcements
    1. Turing's Cathedral: The Origins of the Digital Universe, Pantheon
    2. Imagine: How Creativity Works, Houghton Mifflin Harcourt
    3. Think Complexity: Complexity Science and Computational Modeling, O'Reilly Media
  20. Links & Snippets
    1. Other Publications
    2. Event Announcements
    3. Video Announcements
    4. Other Announcements

  1. Alan Turing at 100, Nature Next Article Bookmark and Share

    Summary:
    Image credit: Andy Potts;Turing family
    Alan Turing, born a century ago this year, is best known for his wartime code-breaking and for inventing the 'Turing machine' " the concept at the heart of every computer today. But his legacy extends much further: he founded the field of artificial intelligence, proposed a theory of biological pattern formation and speculated about the limits of computation in physics. In this collection of features and opinion pieces, Nature celebrates the mind that, in a handful of papers over a tragically short lifetime, shaped many of the hottest fields in science today.

  2. Early Warning Signals for Critical Transitions: A Generalized Modeling Approach, PLoS Comput Biol Next Article Bookmark and Share

    Summary: Fisheries, coral reefs, productive farmland, planetary climate, neural activity in the brain, and financial markets are all complex systems that can be susceptible to sudden changes leading to drastic re-organization or collapse. A variety of signals based on analysis of time-series data have been proposed that would provide warning of these so-called critical transitions. We propose a new method for calculating early warning signals that is complementary to existing approaches. The key step is to incorporate other available information about the system through the framework of a so-called generalized model. Our new approach may help to anticipate future catastrophic regime shifts in nature and society, allowing humankind to avert or to mitigate the consequences of the impending change.

  3. Stability criteria for complex ecosystems, Nature Next Article Bookmark and Share

    Excerpt: Forty years ago, May proved that sufficiently large or complex ecological networks have a probability of persisting that is close to zero, contrary to previous expectations. May analysed large networks in which species interact at random. However, in natural systems pairs of species have well-defined interactions (for example predator"prey, mutualistic or competitive). Here we extend May’s results to these relationships and find remarkable differences between predator"prey interactions, which are stabilizing, and mutualistic and competitive interactions, which are destabilizing. We provide analytic stability criteria for all cases. (…)

  4. A measure of individual role in collective dynamics, Scientific Reports Next Article Bookmark and Share

    Abstract: Identifying key players in collective dynamics remains a challenge in several research fields, from the efficient dissemination of ideas to drug target discovery in biomedical problems. The difficulty lies at several levels: how to single out the role of individual elements in such intermingled systems, or which is the best way to quantify their importance. Centrality measures describe a node's importance by its position in a network. The key issue obviated is that the contribution of a node to the collective behavior is not uniquely determined by the structure of the system but it is a result of the interplay between dynamics and network structure. We show that dynamical influence measures explicitly how strongly a node's dynamical state affects collective behavior. For critical spreading, dynamical influence targets nodes according to their spreading capabilities. For diffusive processes it quantifies how efficiently real systems may be controlled by manipulating a single node.

  5. Peter Diamandis: Abundance is our future, TED.com Next Article Bookmark and Share

    About this talk: Onstage at TED2012, Peter Diamandis makes a case for optimism -- that we'll invent, innovate and create ways to solve the challenges that loom over us. "I’m not saying we don’t have our set of problems; we surely do. But ultimately, we knock them down.”

    1. Vijay Kumar: Robots that fly ... and cooperate, TED.com Next Article Bookmark and Share

      About this talk: In his lab at Penn, Vijay Kumar and his team build flying quadrotors, small, agile robots that swarm, sense each other, and form ad hoc teams -- for construction, surveying disasters and far more.

    2. Shlomo Benartzi: Saving for tomorrow, tomorrow, TED.com Next Article Bookmark and Share

      About this talk: It's easy to imagine saving money next week, but how about right now? Generally, we want to spend it. Economist Shlomo Benartzi says this is one of the biggest obstacles to saving enough for retirement, and asks: How do we turn this behavioral challenge into a behavioral solution?

  6. Modeling the Adoption of Innovations in the Presence of Geographic and Media Influences, PLoS ONE Next Article Bookmark and Share

    Abstract: While there is a large body of work examining the effects of social network structure on innovation adoption, models to date have lacked considerations of real geography or mass media. In this article, we show these features are crucial to making more accurate predictions of a social contagion and technology adoption at a city-to-city scale. Using data from the adoption of the popular micro-blogging platform, Twitter, we present a model of adoption on a network that places friendships in real geographic space and exposes individuals to mass media influence. We show that homophily both among individuals with similar propensities to adopt a technology and geographic location is critical to reproducing features of real spatiotemporal adoption. Furthermore, we estimate that mass media was responsible for increasing Twitter's user base two to four fold. To reflect this strength, we extend traditional contagion models to include an endogenous mass media agent that responds to those adopting an innovation as well as influencing agents to adopt themselves.

  7. The Robustness and Restoration of a Network of Ecological Networks, Science Next Article Bookmark and Share

    Abstract: Understanding species’ interactions and the robustness of interaction networks to species loss is essential to understand the effects of species’ declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity.

  8. The case for open computer programs, Nature Next Article Bookmark and Share

    Summary: Scientific communication relies on evidence that cannot be entirely included in publications, but the rise of computational science has added a new layer of inaccessibility. Although it is now accepted that data should be made available on request, the current regulations regarding the availability of software are inconsistent. We argue that, with some exceptions, anything less than the release of source programs is intolerable for results that depend on computation. The vagaries of hardware, software and natural language will always ensure that exact reproducibility remains uncertain, but withholding code increases the chances that efforts to reproduce results will fail.

  9. Encouraging Behavioral Diversity in Evolutionary Robotics: An Empirical Study, Evolutionary Computation Next Article Bookmark and Share

    Excerpt: Evolutionary robotics (ER) aims at automatically designing robots or controllers of robots without having to describe their inner workings. To reach this goal, ER researchers primarily employ phenotypes that can lead to an infinite number of robot behaviors and fitness functions that only reward the achievement of the task"and not how to achieve it. These choices make ER particularly prone to premature convergence. To tackle this problem, several papers recently proposed to explicitly encourage the diversity of the robot behaviors, rather than the diversity of the genotypes as in classic evolutionary optimization. Such an approach avoids the need to compute distances between structures and the pitfalls of the noninjectivity of the phenotype/behavior relation; however, it also introduces new questions: how to compare behavior? should this comparison be task specific? and what is the best way to encourage diversity in this context? In this paper, we review the main published approaches to behavioral diversity and benchmark them in a common framework. (…)

  10. Fly out-smarts man, arXiv Next Article Bookmark and Share

    Abstract: Precopulatory courtship is a high-cost, non-well understood animal world mystery. Drosophila's (=D.'s) precopulatory courtship not only shows marked structural similarities with mammalian courtship, but also with human spoken language. This suggests the study of purpose, modalities and in particular of the power of this language and to compare it to human language. Following a mathematical symbolic dynamics approach, we translate courtship videos of D.'s body language into a formal language. This approach made it possible to show that D. may use its body language to express individual information - information that may be important for evolutionary optimization, on top of the sexual group membership. Here, we use Chomsky's hierarchical language classification to characterize the power of D.'s body language, and then compare it with the power of languages spoken by humans. We find that from a formal language point of view, D.'s body language is at least as powerful as the languages spoken by humans. From this we conclude that human intellect cannot be the direct consequence of the formal grammar complexity of human language.
    • Source: Fly out-smarts man, Ruedi Stoop, Patrick Nüesch, Ralph Lukas Stoop, and Leonid Bunimovich, arXiv:1202.5913, 2012/02/27

    1. Spread of Social Information and Dynamics of Social Transmission within Drosophila Groups, Current Biology Next Article Bookmark and Share

      Summary: Understanding how behavioral diversity arises and is maintained is central to evolutionary biology. Genetically based inheritance has been a predominant research focus of the last century; however, nongenetic inheritance, such as social transmission, has become a topic of increasing interest [1]. How social information impacts behavior depends on the balance between information gathered directly through personal experience versus that gleaned through social interactions and on the diffusion of this information within groups [2,3]. We investigate how female Drosophila melanogaster use social information under seminatural conditions and whether this information can spread and be maintained within a group, a prerequisite for establishing behavioral transmission [4]. We show that oviposition site choice is heavily influenced by previous social interactions. Naive observer flies develop a preference for the same egg-laying medium as experienced demonstrator flies conditioned to avoid one of two equally rewarding media. Surprisingly, oviposition site preference was socially transmitted from demonstrators to observers even when they interacted in a cage with only unflavored, pure agar medium, and even when the observer flies had previous personal experience with both rewarding media. Our findings shed light on the diffusion process of social information within groups, on its maintenance, and ultimately, on the roots of behavioral local adaptation.

  11. Econophysics of a religious cult: the Antoinists in Belgium [1920-2000], arXiv Next Article Bookmark and Share

    Abstract: In the framework of applying econophysics ideas in religious topics, the finances of the Antoinist religious movement organized in Belgium between 1920 and 2000 are studied. The interest of investigating financial aspects of such a, sometimes called, sect stems in finding characteristics of conditions and mechanisms under which definitely growth AND decay features of communities can be understood. The legally reported yearly income and expenses between 1920 and 2000 are studied. A three wave asymmetric regime is observed over a trend among marked fluctuations at time of crises. The data analysis leads to propose a general mechanistic model taking into account an average GDP growth, an oscillatory monetary inflation and a logistic population drift.

  12. Identification of the Social and Cognitive Processes Underlying Human Cumulative Culture, Science Next Article Bookmark and Share

    Abstract: The remarkable ecological and demographic success of humanity is largely attributed to our capacity for cumulative culture, with knowledge and technology accumulating over time, yet the social and cognitive capabilities that have enabled cumulative culture remain unclear. In a comparative study of sequential problem solving, we provided groups of capuchin monkeys, chimpanzees, and children with an experimental puzzlebox that could be solved in three stages to retrieve rewards of increasing desirability. The success of the children, but not of the chimpanzees or capuchins, in reaching higher-level solutions was strongly associated with a package of sociocognitive processes"including teaching through verbal instruction, imitation, and prosociality"that were observed only in the children and covaried with performance.

  13. Evolution of the Earliest Horses Driven by Climate Change in the Paleocene-Eocene Thermal Maximum, Science Next Article Bookmark and Share

    Abstract: Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts in temperature and possibly high atmospheric CO2 concentrations. These findings could be important for understanding mammalian evolutionary responses to future global warming.

  14. Collapse of Classic Maya Civilization Related to Modest Reduction in Precipitation, Science Next Article Bookmark and Share

    Abstract: The disintegration of the Classic Maya civilization in the Yucatán Peninsula and Central America was a complex process that occurred over an approximately 200-year interval and involved a catastrophic depopulation of the region. Although it is well established that the civilization collapse coincided with widespread episodes of drought, their nature and severity remain enigmatic. We present a quantitative analysis that offers a coherent interpretation of four of the most detailed paleoclimate records of the event. We conclude that the droughts occurring during the disintegration of the Maya civilization represented up to a 40% reduction in annual precipitation, probably due to a reduction in summer season tropical storm frequency and intensity.

  15. Interaction Histories and Short Term Memory: Enactive Development of Turn-taking Behaviors in a Childlike Humanoid Robot, arXiv Next Article Bookmark and Share

    Abstract: In this article, an enactive architecture is described that allows a humanoid robot to learn to compose simple actions into turn-taking behaviors while playing interaction games with a human partner. The robot's action choices are reinforced by social feedback from the human in the form of visual attention and measures of behavioral synchronization. We demonstrate that the system can acquire and switch between behaviors learned through interaction based on social feedback from the human partner. The role of reinforcement based on a short term memory of the interaction is experimentally investigated. Results indicate that feedback based only on the immediate state is insufficient to learn certain turn-taking behaviors. Therefore some history of the interaction must be considered in the acquisition of turn-taking, which can be efficiently handled through the use of short term memory.

  16. State concentration measure of quickness in Kauffman-type networks, arXiv Next Article Bookmark and Share

    Abstract: The quickness of large network dynamics is quantified by the length of transient paths, an analytically intractable measure. We address this dilemma with a unified framework termed state concentration, defined as the exponent of the average number of t-step ancestors in state transition graphs, where nodes represent states and directed links are transitions. Using this exponent to interrogate random Boolean and majority vote networks, we find that dense majority vote networks can achieve both quickness and robustness, owing in part to long-tailed indegree distributions.

  17. Quantitative analyses of empirical fitness landscapes, arXiv Next Article Bookmark and Share

    Abstract: The concept of a fitness landscape is a powerful metaphor that offers insight into various aspects of evolutionary processes and guidance for the study of evolution. Until recently, empirical evidence on the ruggedness of these landscapes was lacking, but since it became feasible to construct all possible genotypes containing combinations of a limited set of mutations, the number of studies has grown to a point where a classification of landscapes becomes possible. The aim of this review is to identify measures of epistasis that allow a meaningful comparison of fitness landscapes and then apply them to the empirical landscapes to discern factors that affect ruggedness. The various measures of epistasis that have been proposed in the literature appear to be equivalent. Our comparsion shows that the ruggedness of the empirical landscape is affected by whether the included mutations are beneficial or deleterious and by whether intra- or intergenic epistasis is involved. Finally, the empirical landscapes are compared to landscapes generated with the Rough Mt. Fuji model. Despite the simplicity of this model, it captures the features of the experimental landscapes remarkably well.

  18. Complexity of networks II: The set complexity of edge-colored graphs, Complexity Next Article Bookmark and Share

    Excerpt: We previously introduced the concept of “set-complexity,” based on a context-dependent measure of information, and used this concept to describe the complexity of gene interaction networks. In a previous paper of this series we analyzed the set-complexity of binary graphs. Here, we extend this analysis to graphs with multicolored edges that more closely match biological structures like the gene interaction networks. All highly complex graphs by this measure exhibit a modular structure. A principal result of this work is that for the most complex graphs of a given size the number of edge colors is equal to the number of “modules” of the graph.

  19. Book Announcements Next Article Bookmark and Share

    1. Turing's Cathedral: The Origins of the Digital Universe, Pantheon Next Article Bookmark and Share

      Summary:
      �It is possible to invent a single machine which can be used to compute any computable sequence,� twenty-four-year-old Alan Turing announced in 1936. In Turing�s Cathedral, George Dyson focuses on a small group of men and women, led by John von Neumann at the Institute for Advanced Study in Princeton, New Jersey, who built one of the first computers to realize Alan Turing�s vision of a Universal Machine. Their work would break the distinction between numbers that mean things and numbers that do things�and our universe would never be the same. Using five kilobytes of memory (the amount allocated to displaying the cursor on a computer desktop of today), they achieved unprecedented success in both weather prediction and nuclear weapons design, while tackling, in their spare time, problems ranging from the evolution of viruses to the evolution of stars. How did code take over the world? In retracing how Alan Turing�s one-dimensional model became John von Neumann�s two-dimensional implementation, Turing�s Cathedral offers a series of provocative suggestions as to where the digital universe, now fully three-dimensional, may be heading next.

    2. Imagine: How Creativity Works, Houghton Mifflin Harcourt Next Article Bookmark and Share

      Summary:
      Did you know that the most creative companies have centralized bathrooms? That brainstorming meetings are a terrible idea? That the color blue can help you double your creative output? From the best-selling author of How We Decide comes a sparkling and revelatory look at the new science of creativity. Shattering the myth of muses, higher powers, even creative �types,� Jonah Lehrer demonstrates that creativity is not a single gift possessed by the lucky few. It�s a variety of distinct thought processes that we can all learn to use more effectively. Lehrer reveals the importance of embracing the rut, thinking like a child, daydreaming productively, and adopting an outsider�s perspective (travel helps). He unveils the optimal mix of old and new partners in any creative collaboration, and explains why criticism is essential to the process. Then he zooms out to show how we can make our neighborhoods more vibrant, our companies more productive, and our schools more effective. (...)

    3. Think Complexity: Complexity Science and Computational Modeling, O'Reilly Media Next Article Bookmark and Share

      Summary:
      Dive into Python�s advanced possibilities, including algorithm analysis, graphs, scale-free networks, and cellular automata with this in-depth, hands-on guide. Whether you�re an intermediate-level Python programmer, or a student of computational modeling, you�ll examine data structures, complexity science, and other fascinating topics through a series of exercises, easy-to-understand explanations, and case studies.

  20. Links & Snippets Next Article Bookmark and Share

    1. Other Publications Next Article Bookmark and Share

      1. Metabolic cost as an organizing principle for cooperative learning, David Balduzzi, Pedro A Ortega, Michel Besserve, 2012/02/20, arXiv:1202.4482
      2. Genealogies in simple models of evolution, Éric Brunet and Bernard Derrida, 2012/02/27, arXiv:1202.5997

    2. Event Announcements Next Article Bookmark and Share

      1. 3rd Workshop on Complex Networks, Melbourne, Florida, USA, 2012/03/7-9
      2. evostar - the main european events on evolutionary computation eurogp, evocop, evobio, evomusart and evoapplications, Málaga, Spain, 2012/03/11-13
      3. 9th International Conference on the Evolution of Language (Evolang IX), Kyoto, Japan, 2012/03/13-16
      4. IWSOS'12 (Sixth International Workshop on Self-Organizing Systems), Delft, The Netherlands, 2012/03/15-16
      5. 5th International Nonlinear Science Conference 2012, Barcelona, Spain, 2012/03/15-17
      6. 6th International Workshop on Natural Computing, Tokyo, Japan, 2012/03/28-30
      7. IPCAT 2012: Ninth International Conference on Information Processing in Cells and Tissues, Cambridge, United Kingdom, 2012/03/31-04/02
      8. 21st European Meeting on Cybernetics and Systems Research, Vienna, Austria, 2012/04/10-13
      9. Collective Intelligence 2012, Cambridge, MA, USA, 2012/04/18-20
      10. The Fifth IFAC Symposium on Fractional Differentiation and Its Applications - FDA12, Nanjing, China, 2012/05/14-17
      11. The Science of Complexity: Understanding the Global Financial Crisis, Arlington, Virginia, 2012/05/16-18
      12. International Spring School in Natural Computing (SSNC 2012), Tarragona, Spain, 2012/05/28-06/1
      13. 1st Annual Conference on Complexity and Human Experience: Modeling Complexity in the Humanities and Social Sciences, Charlotte, NC, USA, 2012/05/30-06/01
      14. MABS’12 - The Thirteenth International Workshop on Multi-Agent-Based Simulation " Multi-Agent Simulation of/and the Society, Valencia, Spain, 2012/06/4-5
      15. 2012 IEEE World Congress on Computational Intelligence, Brisbane, Australia, 2012/06/10-15
      16. CiE 2012 Turing Centenary conference: How the World Computes, Cambridge, UK, 2012/06/18-23
      17. International Conference on Information Society (i-Society 2012), London, UK, 2012/06/25-28
      18. 8th International Conference on Intelligent Environments (IE'12), Guanajuato, Mexico, 2012/06/26-29
      19. Cellular Automata Algorithms & Architectures (CAAA 2012), Madrid, Spain, 2012/07/2-6
      20. Third Summer School of the European Social Simulation Association (ESSA), Toulouse, France, 2012/07/2-6
      21. 2012 Genetic and Evolutionary Computation Conference (GECCO 2012), Philadelphia, USA, 2012/07/7-11
      22. 25th European Conference on Operational Research, Vilnius, Lithuania, 2012/07/8-11
      23. ALife XIII: The Thirteenth International Conference on the Simulation and Synthesis of Living Systems, East Lansing, Michigan, USA, 2012/08/19-22
      24. The Fourth International Conference on Advanced Cognitive Technologies and Applications: COGNITIVE 2012, Nice, France, 2012/07/22-27
      25. 12th International Conference on Adaptive Behaviour (SAB2012), Odense, Denmark, 2012/08/27-31
      26. The 11th International Conference on Artificial Immune Systems - ICARIS 2012, Taormina, Italy, 2012/08/28-31
      27. 12th International Conference on Parallel Problem Solving From Nature (PPSN2012), Taormina, Italy, 2012/09/1-5
      28. ECCS'12: European Conference on Complex Systems, Brussels, Belgium, 2012/09/3-7
      29. 6th IEEE International Conference on Self-Adaptive and Self-Organizing Systems (SASO 2012), Lyon, France, 2012/09/10-14
      30. Interdisciplinary Symposium on Complex Systems, Kos island, Greece, 2012/09/19-25
      31. 10th International Conference on Cellular Automata for Research and Industry (ACRI 2012), Santorini Island, Greece, 2012/09/24-27
      32. 1st International Conference on the Theory and Practice of Natural Computing, TPNC 2012, Tarragona, Spain, 2012/10/1-5
      33. International Joint Conference on Computational Intelligence, Barcelona, Spain, 2012/10/5-7
      34. IBERAMIA 2012: 13th Ibero-American Conference on Artificial Intelligence, Cartagena de Indias, Colombia, 2012/11/13-16

    3. Video Announcements Next Article Bookmark and Share

      1. Complexity Digest videos and Webcast Archive.
      2. Lakeside Labs videos.
      3. FuturICT videos.
      4. Brain-Mind Institute webinars
      5. IFISC@uib.es seminars.
      6. ASSYST Digital Library.
      7. TED Talks.
      8. Edge Videos
      9. CERN Webcast Service.
      10. Dean LeBaron's Video Casts.

    4. Other Announcements Bookmark and Share


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