Differences among species in their ability to adapt to environmental change threaten biodiversity, human health, food security, and natural resource availability. Pathogens, pests, and cancers often quickly evolve resistance to control measures, whereas crops, livestock, wild species, and human beings often do not adapt fast enough to cope with climate change, habitat loss, toxicants, and lifestyle change. To address these challenges, practices based on evolutionary biology can promote sustainable outcomes via strategic manipulation of genetic, developmental, and environmental factors. Successful strategies effectively slow unwanted evolution and reduce fitness in costly species or improve performance of valued organisms by reducing phenotype-environment mismatch or increasing group productivity. Tactics of applied evolutionary biology range broadly, from common policies that promote public health or preserve habitat for threatened species—but are easily overlooked as having an evolutionary rationale, to the engineering of new genomes.
Applying evolutionary biology to address global challenges Scott P. Carroll, et al.
Although human and animal behaviors are largely shaped by reinforcement and punishment, choices in social settings are also influenced by information about the knowledge and experience of other decision-makers. During competitive games, monkeys increased their payoffs by systematically deviating from a simple heuristic learning algorithm and thereby countering the predictable exploitation by their computer opponent. Neurons in the dorsomedial prefrontal cortex (dmPFC) signaled the animal’s recent choice and reward history that reflected the computer’s exploitative strategy. The strength of switching signals in the dmPFC also correlated with the animal’s tendency to deviate from the heuristic learning algorithm. Therefore, the dmPFC might provide control signals for overriding simple heuristic learning algorithms based on the inferred strategies of the opponent.
Neural correlates of strategic reasoning during competitive games Hyojung Seo, Xinying Cai, Christopher H. Donahue, Daeyeol Lee
Group selection may be defined as selection caused by the differential extinction or proliferation of groups. The socially polymorphic spider Anelosimus studiosus exhibits a behavioural polymorphism in which females exhibit either a ‘docile’ or ‘aggressive’ behavioural phenotype. Natural colonies are composed of a mixture of related docile and aggressive individuals, and populations differ in colonies’ characteristic docile:aggressive ratios. Using experimentally constructed colonies of known composition, here we demonstrate that population-level divergence in docile:aggressive ratios is driven by site-specific selection at the group level—certain ratios yield high survivorship at some sites but not others. Our data also indicate that colonies responded to the risk of extinction: perturbed colonies tended to adjust their composition over two generations to match the ratio characteristic of their native site, thus promoting their long-term survival in their natal habitat. However, colonies of displaced individuals continued to shift their compositions towards mixtures that would have promoted their survival had they remained at their home sites, regardless of their contemporary environment. Thus, the regulatory mechanisms that colonies use to adjust their composition appear to be locally adapted. Our data provide experimental evidence of group selection driving collective traits in wild populations.
Site-specific group selection drives locally adapted group compositions • Jonathan N. Pruitt & Charles J. Goodnight
Your genome is the same right now as it was yesterday, last week, last year, or the day you were born. But your microbiomes—the combined genes of all the trillions of microbes that share your body—have shifted since the sun came up this morning. And they will change again before the next sunrise.
We investigate the role of networks of alliances in preventing (multilateral) interstate wars. We first show that, in the absence of international trade, no network of alliances is peaceful and stable. We then show that international trade induces peaceful and stable networks: trade increases the density of alliances so that countries are less vulnerable to attack and also reduces countries' incentives to attack an ally. We present historical data on wars and trade, noting that the dramatic drop in interstate wars since 1950, and accompanying densification and stabilization of alliances, are consistent with the model but not other prominent theories.
Networks of Military Alliances, Wars, and International Trade Matthew O. Jackson, Stephen M. Nei
In this work we present analytic expressions for the expected values of the performance metrics of parallel applications when the distributed computing infrastructure has a complex topology. Through active probing tests we analyse the structure of a real distributed computing environment. From the resulting network we both validate the analytic expressions and explore the performance metrics under different conditions through Monte Carlo simulations. In particular we gauge computing paradigms with different hierarchical structures in computing services. Fully decentralised (i.e., peer-to-peer) environments provide the best performance. Moreover, we show that it is possible to improve significantly the parallel efficiency by implementing more intelligent configurations of computing services and task allocation strategies (e.g., by using a betweenness centrality measure). We qualitatively reproduce results of previous works and provide closed-form solutions that link topology, application’s structure and allocation parameters when job dependencies and a complex network structure are considered.
Distributed Computing on Complex Networks Francisco Prieto-Castrillo, Antonio Astillero, María Botón-Fernández
Although the role of epistasis in evolution has received considerable attention from experimentalists and theorists alike, it is unknown which aspects of adaptation are in fact sensitive to epistasis. Here, we address this question by comparing the evolutionary dynamics on all finite epistatic landscapes versus all finite non-epistatic landscapes, under weak mutation. We first analyze the fitness trajectory -- that is, the time course of the expected fitness of a population. We show that for any epistatic fitness landscape and choice of starting genotype, there always exists a non-epistatic fitness landscape and starting genotype that produces the exact same fitness trajectory. Thus, surprisingly, the presence or absence of epistasis is irrelevant to the first-order dynamics of adaptation. On the other hand, we show that the time evolution of the variance in fitness across replicate populations can be sensitive to epistasis: some epistatic fitness landscapes produce variance trajectories that cannot be produced by any non-epistatic landscape. Likewise, the mean substitution trajectory -- that is, the expected number of mutations that fix over time -- is also sensitive to epistasis. These results on identifiability have direct implications for efforts to infer epistasis from the types of data often measured in experimental populations.
On the role of epistasis in adaptation David M. McCandlish, Jakub Otwinowski, Joshua B. Plotkin
How do we know where we are? How can we find the way from one place to another? And how can we store this information in such a way that we can immediately find the way the next time we trace the same path? This year´s Nobel Laureates have discovered a positioning system, an “inner GPS” in the brain that makes it possible to orient ourselves in space, demonstrating a cellular basis for higher cognitive function.
For a long time optical microscopy was held back by a presumed limitation: that it would never obtain a better resolution than half the wavelength of light. Helped by fluorescent molecules the Nobel Laureates in Chemistry 2014 ingeniously circumvented this limitation. Their ground-breaking work has brought optical microscopy into the nanodimension.
Non-caloric artificial sweeteners (NAS) are among the most widely used food additives worldwide, regularly consumed by lean and obese individuals alike. NAS consumption is considered safe and beneficial owing to their low caloric content, yet supporting scientific data remain sparse and controversial. Here we demonstrate that consumption of commonly used NAS formulations drives the development of glucose intolerance through induction of compositional and functional alterations to the intestinal microbiota. These NAS-mediated deleterious metabolic effects are abrogated by antibiotic treatment, and are fully transferrable to germ-free mice upon faecal transplantation of microbiota configurations from NAS-consuming mice, or of microbiota anaerobically incubated in the presence of NAS. We identify NAS-altered microbial metabolic pathways that are linked to host susceptibility to metabolic disease, and demonstrate similar NAS-induced dysbiosis and glucose intolerance in healthy human subjects. Collectively, our results link NAS consumption, dysbiosis and metabolic abnormalities, thereby calling for a reassessment of massive NAS usage.
Artificial sweeteners induce glucose intolerance by altering the gut microbiota • Jotham Suez, Tal Korem, David Zeevi, Gili Zilberman-Schapira, Christoph A. Thaiss, Ori Maza, David Israeli, Niv Zmora, Shlomit Gilad, Adina Weinberger, Yael Kuperman, Alon Harmelin, Ilana Kolodkin-Gal, Hagit Shapiro, Zamir Halpern, Eran Segal & Eran Elinav
Teotihuacan was the first urban civilization of Mesoamerica and one of the largest of the ancient world. Following a tradition in archaeology to equate social complexity with centralized hierarchy, it is widely believed that the city’s origin and growth was controlled by a lineage of powerful individuals. However, much data is indicative of a government of co-rulers, and artistic traditions expressed an egalitarian ideology. Yet this alternative keeps being marginalized because the problems of collective action make it difficult to conceive how such a coalition could have functioned in principle. We therefore devised a mathematical model of the city’s hypothetical network of representatives as a formal proof of concept that widespread cooperation was realizable in a fully distributed manner. In the model, decisions become self-organized into globally optimal configurations even though local representatives behave and modify their relations in a rational and selfish manner. This self-optimization crucially depends on occasional communal interruptions of normal activity, and it is impeded when sections of the network are too independent. We relate these insights to theories about community-wide rituals at Teotihuacan and the city’s eventual disintegration.
Froese T, Gershenson C, Manzanilla LR (2014) Can Government Be Self-Organized? A Mathematical Model of the Collective Social Organization of Ancient Teotihuacan, Central Mexico. PLoS ONE 9(10): e109966. http://dx.doi.org/10.1371/journal.pone.0109966
Profiting from the emergence of web-scale social data sets, numerous recent studies have systematically explored human mobility patterns over large populations and large time scales. Relatively little attention, however, has been paid to mobility and activity over smaller time-scales, such as a day. Here, we use Twitter to identify people's frequently visited locations along with their likely activities as a function of time of day and day of week, capitalizing on both the content and geolocation of messages. We subsequently characterize people's transition pattern motifs and demonstrate that spatial information is encoded in word choice.
Constructing a taxonomy of fine-grained human movement and activity motifs through social media Morgan R. Frank, Jake Ryland Williams, Lewis Mitchell, James P. Bagrow, Peter Sheridan Dodds, Christopher M. Danforth
According to Zipf's meaning-frequency law, words that are more frequent tend to have more meanings. Here it is shown that a linear dependency between the frequency of a form and its number of meanings is found in a family of models of Zipf's law for word frequencies. This is evidence for a weak version of the meaning-frequency law. Interestingly, that weak law (a) is not an inevitable of property of the assumptions of the family and (b) is found at least in the narrow regime where those models exhibit Zipf's law for word frequencies.
The meaning-frequency law in Zipfian optimization models of communication Ramon Ferrer-i-Cancho
When the first universities emerged in eleventh-century Europe, their mission was education, scholarship and nothing else. They housed bright young clerics, studying the newly rediscovered works of ancient thinkers such as Aristotle and Euclid. Only in the nineteenth century, following the lead of Britain and Germany, did universities begin to give equal weight to a second mission: scientific research.
But in the past few decades, universities around the world have begun to take on further missions. Today they are supposed to be not only centres of education and discovery, but also engines of economic growth, beacons of social justice and laboratories for new modes of learning.
(...) humans and other species seem to share basic reactions to inequity, which serves to sustain cooperation. We postulate that the basic emotional reactions and calculations underlying our sense of fairness are rooted in our primate background and offer a model that places these reactions in the context of cooperative relationships.
Evolution of responses to (un)fairness Sarah F. Brosnan1,*, Frans B. M. de Waal
Autophagy is the mechanism by which cellular material is delivered to lysosomes and degraded. This process has become a major focus of biological and biomedical research with thousands of papers published each year and rapidly growing appreciation that autophagy affects many normal and pathological processes. However, as we learn more about this evolutionarily ancient process, we are discovering that autophagy's effects may work for both the good and the bad of an organism. Here, I discuss some of these context-dependent findings and how, as we make sense of them, we can try to apply our knowledge for practical purposes.
Explosive synchronization (ES) is nowadays a hot topic of interest in nonlinear science and complex networks. So far, it is conjectured that ES is rooted in the setting of specific microscopic correlation features between the natural frequencies of the networked oscillators and their effective coupling strengths. We show that ES, in fact, is far more general, and can occur in adaptive and multilayer networks also in the absence of such correlation properties. Precisely, we first report evidence of ES in the absence of correlation for networks where a fraction f of the nodes have links adaptively controlled by a local order parameter, and then we extend the study to a variety of two-layer networks with a fraction f of their nodes coupled each other by means of dependency links. In this latter case, we even show that ES sets in, regardless of the differences in the frequency distribution and/or in the topology of connections between the two layers. Finally, we provide a rigorous, analytical, treatment to properly ground all the observed scenario, and to facilitate the understanding of the actual mechanisms at the basis of ES in real-world systems.
Explosive synchronization in adaptive and multilayer networks Xiyun Zhang, Stefano Boccaletti, Shuguang Guan, Zonghua Liu
The dynamics of rule 54 one-dimensional two-state cellular automaton (CA) are a discrete analog of a space-time dynamics of excitations in nonlinear active medium with mutual inhibition. A cell switches its state 0 to state 1 if one of its two neighbors is in state 1 (propagation of a perturbation) and a cell remains in state 1 only if its two neighbors are in state 0. A lateral inhibition is because a 1-state neighbor causes a 1-state cell to switch to state 0. The rule produces a rich spectrum of space-time dynamics, including gliders and glider guns just from four primitive gliders. We construct a catalogue of gliders and describe them by tiles. We calculate a subset of regular expressions ΨR54 to encode gliders. The regular expressions are derived from de Bruijn diagrams, tile-based representation of gliders, and cycle diagrams sometimes. We construct an abstract machine that recognizes regular expressions of gliders in rule 54 and validate Ψ R54. We also propose a way to code initial configurations of gliders to depict any type of collision between the gliders and explore self-organization of gliders, formation of larger tiles, and soliton-like interactions of gliders and computable devices.
Complete Characterization of Structure of Rule 54 Genaro J. Martínez, Andrew Adamatzky, Harold V. McIntosh
Connection topologies of many networked systems like human brain, biological cell, world wide web, power grids, human society and ecological food webs markedly deviate from that of completely random networks indicating the presence of organizing principles behind their evolution. The five important features that characterize such networks are scale-free topology, small average path length, high clustering, hierarchical community structure and assortative mixing. Till now the generic mechanisms underlying the existence of these properties are not well understood. Here we show that potentially a single mechanism, which we call "mediated attachment", where two nodes get connected through a mediator or common neighbor, could be responsible for the emergence of all important properties of real networks. The mediated attachment naturally unifies scale-free topology, high clustering, small world nature, hierarchical community structure and dissortative nature of networks. Further, with additional mixing by age, this can also explain the assortative structure of social networks. The mechanism of mediated attachment seems to be directly present in acquaintance networks, co-authorships, World Wide Web, metabolic networks, co-citations and linguistics. We anticipate that this mechanism will shed new light on percolation and robustness properties of real world networks as well as would give new insights in processes like epidemics spreading and emergent dynamics taking place on them.
Mediated attachment as a mechanism for growth of complex networks Snehal M. Shekatkar, G. Ambika
Jean Tirole is one of the most influential economists of our time. He has made important theoretical research contributions in a number of areas, but most of all he has clarified how to understand and regulate industries with a few powerful firms.
This year’s Nobel Laureates are rewarded for having invented a new energy-efficient and environment-friendly light source – the blue light-emitting diode (LED). In the spirit of Alfred Nobel the Prize rewards an invention of greatest benefit to mankind; using blue LEDs, white light can be created in a new way. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources.
Autonomous machines have gripped our imagination ever since the first robot flickered on the silver screen, Maria in the 1927 film Metropolis. Most of the robots we know today—unglamorous devices like robotic welders on car assembly lines and the Roomba vacuum cleaner—fall short of those in science fiction. But our relationship with robots is about to become far more intimate. Would you be comfortable with a robot butler, or a self-driving car? How about a robo-scientist toiling away next to you at the bench, not only pipetting but also formulating hypotheses and designing experiments?
That social media benefits mankind is irrefutable. I have been an evangelist for the power of new media for 20 years. However, technology in the form of globalized communication, transportation and supply chains conspires to make today’s world more complex. Events in any corner of the world now impact the rest of the globe quickly and sharply. Nations are being pulled apart along sectarian seams in Iraq, tribal divisions in Afghanistan, national interests in Ukraine and territorial fences in Gaza. These conflicts portend a quickening of global unrest, confirmed by Foreign Policy magazine’s map of civil protest. The ISIS videos are simply the exposed wire. I believe that over the next century, even great nations will Balkanize — break into smaller nations. One of the principal drivers of this Balkanization is social media Twitter .
We are pleased to present the first issue of "Human Computation", a new, open-access journal for all disciplines that contribute to the design and analysis of distributed information processing systems that leverage human cognition. We hope you find this first issue both stimulating and useful and look forward to your feedback and – hopefully – to including your own scholarly work in future editions.
Self-organisation occurs in natural phenomena when a spontaneous increase inorder is produced by the interactions of elements of a complex system. Thermodynamically,this increase must be offset by production of entropy which, broadly speaking, can beunderstood as a decrease in order. Ideally, self-organisation can be used to guide the systemtowards a desired regime or state, while “exporting” the entropy to the system’s exterior. Thus, Guided Self-Organisation (GSO) attempts to harness the order-inducing potentialof self-organisation for specific purposes. Not surprisingly, general methods developed tostudy entropy can also be applied to guided self-organisation. This special issue covers a broad diversity of GSO approaches which can be classified in three categories: informationtheory, intelligent agents, and collective behavior. The proposals make another step towardsa unifying theory of GSO which promises to impact numerous research fields.
Entropy Methods in Guided Self-Organisation Mikhail Prokopenko and Carlos Gershenson