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Displaying entries 31 through 45 of 64 found.

Earth Life Emergence: Development of Body, Brain, Selves and Societies

Terui, Akira, et al. Metapopulation Stability in Branching River Networks. Proceedings of the National Academy of Sciences. 115/E5963, 2018. University of Minnesota and Hokkaido University system environmentalists provide a sophisticated analysis of the pervasive presence of self-similar network topologies even in these ever variable fluid flow geoscape regimes.

Intraspecific population diversity is an essential component of metapopulation stability and persistence in nature. However, current theories developed in simplified landscapes may be inadequate to predict emergent properties of branching ecosystems, a prime feature of habitat geometry. Here, we analyze a long-term dataset to show that a scale-invariant characteristic of fractal river networks, branching complexity stabilizes watershed metapopulations. In riverine systems, each branch (tributary) exhibits distinctive ecological dynamics, and confluences serve as “merging” points of those branches. We theoretically revealed that the stabilizing effect of branching complexity is due to probabilistic processes in natural conditions, where within-branch synchrony exceeds among-branch synchrony. (Abstract excerpt)

Cornish-Bowden, Athel and Maria Luz Cardenas. Contrasting Theories of Life: Historical Context, Current Theories. Biosystems. November, 2019. CRNS, University of Marseilles biochemists post a 64 page synoptic review of prior conceptions about how life came to be, evolve and develop. The integral (all male) survey runs from Aristotle to Stuart Kauffman and Karl Friston, with extra time given to Manfred Eigen, Robert Rosen, and Francisco Varela. A steady implication is that some manner of autocatalytic, self-making optimization process is going on.

Most attempts to define life have been individual opinions, but here we compare all of the major current theories. We begin by asking how we know that an entity is alive, and continue by way of the contributions of La Mettrie, Burke, Leduc, Herrera, Bahadur, D’Arcy Thompson and, especially Schrödinger, whose book What is Life? is a vital starting point. All of these incorporate the idea of circularity, but fail to take account of metabolic regulation. In a final section we study the extent to which each of the current theories can aid the search for a more complete theory of life, and explain the characteristics of metabolic control analysis essential for an adequate understanding of organisms. (Abstract)

Szostak, Jack. The Narrow Road to the Deep Past: In Search of the Chemistry of the Origin of Life. Angewandte Chemie International. 56/37, 2017. The Nobel chemist (2009) at the Howard Hughes Medical Institute, Center for Computational and Integrative Biology, Boston writes a popular update on his own work and on the long project to recover and quantify how living, evolving systems came to be. A salient aspect is the appearance of membrane-bounded protocell vesicles, which then play a role in forming vital RNA polymerase replicators. Once life got going, other catalytic biochemicals could complexify toward enzymes, metabolisms all the way to we curious curators.

The sequence of events that gave rise to the first life on our planet took place in the Earth's deep past, seemingly beyond our reach. Understanding the processes that led to the chemical building blocks of biology and how these molecules self‐assembled into cells that could grow, divide and evolve, nurtured by a rich and complex environment, seems insurmountably difficult. And yet, to my own surprise, simple experiments have revealed robust processes that could have driven the growth and division of primitive cell membranes. Even our efforts to combine replicating compartments and genetic materials into a full protocell model have moved forward in unexpected ways. Fortunately, many challenges remain, so the future in this field is brighter than ever! (Abstract)

Jolles, Jolle, et al. The Role of Individual Heterogeneity in Collective Animal Behavior. Trends in Ecology and Evolution. Online December, 2019. Jolle J, MPI Animal Behavior, Andrew King, Swansea University, UK, and Shuan Killen, University of Glasgow scope out ways that an array of diverse member behaviors can actually foster their overall group cohesion and viability.

Social grouping is omnipresent in the animal kingdom. Considerable research has focused on understanding how animal groups form and function, including how collective behaviour emerges via self-organising mechanisms and how phenotypic variation drives the behaviour and functioning of animal groups. Here we present a common framework to quantify heterogeneity in the literature so as to explain and predict its role in collective behaviour across species, contexts, and traits. We show that member diversity provides a key intermediary factor with regard to group structure, functioning, response to environmental change, and evolution. (Abstract)

Whitehead, Hal, et al. The Reach of Gene-Culture Coevolution in Animals. Nature Communications. 10/2405, 2019. A premier team of bioecologists - HW, Kevin Laland, Luke Rendell, Rose Thorogood and Andrew Whiten – describe the creative interplay between genetic source codes and the common presence of behavioral groupings across aquatic, avian and mammalian species. See also Animal Learning as a Source of Developmental Bias by K. Laland, et al in Evolution & Development (e12311, 2019).

Culture (behaviour based on socially transmitted information) is present in diverse animal species, yet how it interacts with genetic evolution remains largely unexplored. Here, we review the evidence for gene–culture coevolution in animals, especially birds, cetaceans and primates. We describe how culture can relax or intensify selection under different circumstances, create new selection pressures by changing ecology or behaviour, and favour adaptations, including in other species. Finally, we illustrate how, through culturally mediated migration and assortative mating, culture can shape population genetic structure and diversity. This evidence suggests that animal culture plays an important coevolutionary role, in nature. (Abstract)

Thiebaut de Schotten, Michel and Karl Zilles, eds. The Evolution of the Mind and Brain. Cortex. 118/1, 2019. An introduction to this special issue with some 20 entries such as The Biological Bases of Color Categorization from Goldfish to the Human Brain, The Left Cradling Bias, Large Scale Comparative Neuroimaging, and The Hippocampus of Birds in a View of Evolutionary Connectomics.

Vallortigara, Giorgio and Lesley Rogers. A Function for the Bicameral Mind. Cortex. Online December, 2019. The University of Trento, Italy and University of New England, Australia senior scholars continue to advance understandings of the pervasive presence and advantages across all phyla of dual brain hemispheres with opposite but complementary discrete particle (seed, me) or whole image (relations, We) attributes. This deep evolutionary benefit is most manifest in human cerebral activity, but we seem to work against this reciprocity as evident by local and global political conflicts. (Here is an example of a worldwide scientific discovery about a vital neural anatomy across animal kingdoms which a male (dots only) academia is unable to comprehend.)

A lateralized brain, in which each hemisphere processes sensory inputs and carries them out in different ways, is common in vertebrates, and it now reported for invertebrates too. As shown in many animal species, having a lateralized brain can enhance the capacity to perform two tasks at the same time. Why is this the case? Not only humans, but also most non-human animals, show a similar pattern of directional asymmetry. For instance, from fish to mammals most individuals react faster when a predator approaches from their left side. Using mathematical theory of games, it has been argued that the population structure of lateralization may result from the type of interactions asymmetric organisms face with each other. (Abstract excerpt)

Mehr, Samuel, et al. University and Diversity in Human Song. Science. 366/eaao868, 2019. Some 19 researchers posted in the USA, Germany, and Canada including Stephen Pinker report upon a comprehensive, cross-cultural study of the past and present occasion of melodious communication, with and without words, which well confirms its personal and societal significance. See also a commentary The World in a Song by Tecumseh Fitch and Tudor Popescu in the same issue.

What is universal about music, and what varies? We built a corpus of ethnographic text on musical behavior from a representative sample of the world’s societies, as well as a discography of audio recordings. The ethnographic corpus reveals that music varies along three formality, arousal, and religiosity aspects, more within societies than across them; and that music is associated with behavioral contexts such as infant care, healing, dance, and love. In addition, acoustic features of tonality are almost universal; music varies in rhythmic and melodic complexity; and elements of melodies and rhythms found worldwide follow power laws. (Abstract excerpt)

Townsend, Simon, et al. Compositionality in Animals and Humans. PLOS Biology. 16/8, 2018. As this long title word gains currency (search) to describe how our language “composes” itself, University of Zurich, Warwick, UK, and of Neuchatel, Switzerland comparative linguists including Sabrina Engesser and Nalthasar Bickel elucidate how this quality can likewise be seen in formative effect across multi-faceted creaturely communications. See also Call Combinations in Birds and the Evolution of Compositional Syntax by Toshitaka Suzuki, et al, in this journal and date.

origins of language’s syntactic structure. One approach seeks to reduce the core of syntax in humans to a single principle of recursive combination for which there is no evidence in other species. We argue for an alternative approach. We review evidence that beneath the complexity of human syntax, there is an extensive layer of nonproductive, nonhierarchical syntax that can well be compared to animal call combinations. This is the essential groundwork that must be in place before we can elucidate, with sufficient precision, what made it possible for human language to explode its syntactic capacity from simple nonproductive combinations. (Abstract edits)

Barabasi, Daniel and Albert-Laszlo Barabasi. A Genetic Model of the Connectome. Neuron. 105/1, 2020. A son and father team a few miles apart at Harvard University (doctoral candidate) and Northeastern University (professor, group leader, founding theorist, search) apply mathematic scale-free network topologies such as biclique graphs (see below) to better trace and join regulatory genomes with cerebral multiplex intricacies. As A-L S’s 2016 Network Science conveys, from its 1998 advent, an ever wider anatomy/physiology-like webwork has been cast and quantified which now spreads from galactic clusters to literary works, and every node/link entity phase in between.

The connectomes of organisms of the same species show architectural and often local wiring similarities, which raises the question: where and how is neuronal connectivity encoded? Our premise is that the genetic identity of neurons should guide synapse and gap-junction formation and show that genetically driven wiring predicts the existence of specific biclique (see below) motifs in the connectome. We identify significant biclique subgraphs in the connectomes of three species and show that the neurons share expression patterns and morphological characteristics. Our proposed model thus offers a self-consistent framework to link the genetics of an organism to the reproducible architecture of its connectome. (Abstract excerpt)

Biclique: A special kind of bipartite graph where every vertex of the first set is connected to every vertex of the second set.

Mozziconacci, Julien, et al. The 3D Genome Shapes the Regulatory Code of Developmental Genes. arXiv:1911.04779. Drawing upon the latest research results, Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensé theoretical geneticists JM, Melody Merle and Annick Lesne contribute a deeper conceptual appreciation of nature’s pervasive, semantic, prescriptive source program.

We revisit the notion of gene regulatory code in embryonic development in the light of new findings about genome spatial organisation. By analogy with the genetic code, we posit that the concept of code can only be used if the corresponding adaptor can clearly be identified. An adaptor is here defined as an intermediary physical entity mediating the correspondence between codewords and objects. In our context, the encoded objects are gene expression levels, while specific transcription factors in the cell nucleus provide the codewords. We propose that an adaptor for this code is the gene domain, that is, the genome segment comprising the gene and its enhancer regulatory sequences. (Abstract excerpt)

Our starting point is the definition of a code that will be used in the present text. Different meanings of this word are encountered in science, from the secret codes in cryptography, the source codes in computer science, to the neural codes and the genetic code. The latter is the emblematic example of a semantic code, in a biological context. The definition of a semantic code relies on three ingredients, namely codewords, objects, and adaptors: codewords are inputs to be interpreted; a single object is associated to each codeword; adaptors are physical entities that implement the association of each codeword with a unique object. (3)

Cao, Miao, et al. Developmental Connectomics from Infancy through Early Childhood. Trends in Neuroscience. 40/8, 2019. Connectome: a complete set of neural elements (neurons, brain regions, etc.) and their interconnections (synapses, fiber pathways, temporal correlations.) Beijing Normal University and Children’s Hospital of Philadelphia cognitive neuroresearchers describe novel computational neuroimaging and neurophysiological methods which are revealing the course followed by cerebral architectures as they mature over the first five years of our lives. See also Mechanisms of Connectome Development by Marcus Kaiser in Trends in Cognitive Sciences (21/9, 2017).

The human brain undergoes rapid growth in both structure and function from infancy through early childhood, which influences cognitive and behavioral development in later life. The new developmental connectomics research field provides new opportunities to study developing brain through the non-invasive mapping of structural and functional connectivity patterns. We investigate connectome formation from 20 postmenstrual weeks to 5 years of age with regard to five fundamental principles of strengthened segregation/integration balance, hierarchical order from primary to higher-order regions, structural and functional maturations, individual variability, and vulnerability to risk factors and developmental disorders. (Abstract excerpt)

Baumgarten, Lorenz and Stefan Bornholdt. Critical Excitation-Inhibition Balance in Dense Neural Networks. arXiv:1903.12632. University of Bremen theorists contribute to later 2010s research findings that our (microcosmic) cerebral faculty inherently seeks and performs best at this tamper-down and/or ramp-up emotional and cognitive state. How grand might it then be if nature’s (macroscopic) tendency to reach such an optimum reciprocity could be carried over and availed in social politics whence dual right-conserve and left-create parties would be complementary halves of a whole organic democracy.

The "edge of chaos" phase transition in artificial neural networks is of renewed interest in light of recent evidence for criticality in brain dynamics. A recent study utilizing the excitation-inhibition ratio as the control parameter found a new, nearly degree independent, critical point when neural connectivity is large. However, the new phase transition is accompanied by a high level of activity in the network. Here we study random neural networks with the additional properties of (i) a high clustering coefficient and (ii) neurons that are either excitatory or inhibitory, a prominent property of natural neurons. As a result, we observe an additional critical point for networks with large connectivity which compares well with neuronal brain networks. (Abstract excerpt)

Bertolero, Maxwell and Danielle Bassett. On the Nature of Explanations Offered by Network Science: A Perspective from and for Neuroscientists. arXiv:1911.05031. In this paper to appear in a special issue of Topics in Cognitive Science, University of Pennsylvania neuroscientists post an illustrated tutorial on the latest research about how our cerebral activities are based on and empowered by myriad, scintillating, multiplex neural nets. What began as patchy rudiments around 2010 has now become a whole-scale theoretical and experimental explanation from nodal neurons to an infinity of relational linkages. Altogether dubbed a connectome, as 2020 nears we human beings are finding ourselves to truly be an exemplary micro-universe. See also Discovering the Computational Relevance of Brain Network Organization by Takuya Ito, et al in Trends in Cognitive Science (online November 2019).

Network neuroscience represents the brain as a collection of regions and inter-regional connections. By this ability, the approach has generated unique explanations of neural function and behavior. Here we complement formal philosophical efforts by providing an applied perspective. In doing so, we rely on philosophical work concerning the role of causality, scale, and mechanisms in scientific explanations. We hope to provide a useful framework in which can be exercised across scales and combined with other fields of neuroscience to gain deeper insights into the brain and behavior. (Abstract excerpt)

Wang, Jilin, et al. Non-equilibrium Critical Dynamics of Bursts in θ and δ Rhythms as Fundamental Characteristic of Sleep and Wake Micro-architecture. PLoS Computational Biology. November, 2019. As the 2010s come to a close, in this Public Library of Science journal Boston University and UM Worcester Medical School researchers including Plamen Ivanov describe experiments and theories so as to report that even our daily resting phase is distinguished by independent, universal complex phenomena. Thus nighttime joins daylight wakefulness which, as Systems Neuroscience cites, prefers to be poised between more or less order. A person’s beingness then joins a quantum, universal complementarity which all other phases and site sections lately attest to. Once again microcosmic selves are vital exemplars of a macrocosmic genesis.

Origin and functions of intermittent transitions among sleep stages, including short awakenings and arousals, challenge the current homeostatic framework for sleep regulation. Here we propose that a complex micro-architecture characterizing the sleep-wake cycle results from an underlying non-equilibrium critical dynamics, bridging collective behaviors across spatio-temporal scales. We demonstrate that intermittent bursts in θ and δ rhythms exhibit a complex temporal organization, with long-range power-law correlations and a robust duality of θ-bursts (active phase) and exponential-like δ-bursts (quiescent phase) durations, which are typical features of non-equilibrium systems self-organizing at criticality. Importantly, such temporal organization relates to anti-correlated coupling between θ- and δ-bursts, and is independent of the dominant physiologic state, a solid indication of a basic principle in sleep dynamics. (Abstract excerpt)

The results demonstrate that critical dynamics underlie cortical activation during sleep and wake, and lay the foundation for a new paradigm, considering sleep micro-architecture as a non-equilibrium process and self-organization among neuronal assemblies to maintain a critical state, in contrast to the homeostasis paradigm of sleep regulation at large time scales. (Author Summary)

Power-law distributions are the statistical hallmark of scale invariance, and are typical features of physical systems at the critical point of a second order phase transition in equilibrium thermodynamics. At criticality systems exhibit high sensitivity to interactions among elements, leading to emergent collective behavior across scales, and thus, power laws. The critical point is located at the border between an ordered and a disordered phase, and can be reached by fine tuning external parameters. In contrast to this scenario, in non-equilibrium systems the dynamics can be spontaneously driven at criticality, where an active phase characterized by bursts/avalanches with power-law distributed sizes and durations coexists with a quiescent phase with exponential-like statistics. (3-4)

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