V. Life's Corporeal Evolution Develops, Encodes and Organizes Itself: An Earthtwinian Genesis Synthesis

4. Multicellular Fauna and Flora Organisms in Transition

Cooper, Rory, et al. An Ancient Turing-like Patterning Mechanism Regulates Skin Denticle Development in Sharks. Science Advances. 4/11, 2018. We cite this paper by University of Sheffield, Oxford and Florida biologists as another current finding that natural evolution seems to avail an independent mathematical source code which then appears in exemplary, recurrent effect across the anatomy and physiology of Metazoan creaturely kingdoms.

Vertebrates have a vast array of epithelial appendages, including scales, feathers, and hair. The developmental patterning of these diverse structures can be theoretically explained by Alan Turing’s reaction-diffusion system. However, the role of this system in epithelial appendage patterning of early diverging lineages such as the cartilaginous fishes is poorly understood.. We demonstrate through simulation models that a Turing-like mechanism can explain shark denticle patterning. This mechanism bears remarkable similarity to avian feather patterning, suggesting deep homology of the system. We propose that a diverse range of vertebrate appendages, from shark denticles to avian feathers and mammalian hair, use this ancient and conserved system. (Abstract)

Crockett, William, et al.. Physical constraints during Snowball Earth drive the evolution of multicellularity. Proceedings of the Royal Society B. June, 2024. With regard to this major biological transition event, WC, MIT, Jack Shaw and Chris Kempes, Sante Fe Institute and Carl Simpson, University of Colorado factor in a global environmental influence which they say impelled microorganisms to band together for sheer survival. As the quotes advise, in retrospect as the whole scenario becomes filled in and fleshed out it does seem to reveal an innate, sequential drive and direction across life’s stratified emergence. See also Experimental Snowball Earth Viscosity Drives the Evolution of Motile Multicellularity by Andrea Halling, et al in bioRxiv (February 8, 2024).

Molecular and fossil evidence suggests that complex eukaryotic multicellularity evolved during the late Neoproterozoic era, coincident with Snowball Earth glaciations, where ice sheets covered most of the globe. During this period, environmental conditions were extreme with significant effects on resource availability and optimal phenotypes. By testing novel hypotheses, we show how multicellularity was likely acquired differently in eukaryotes and prokaryotes owing the biophysical and metabolic regimes they inhabit. These results suggest that adverse conditions during Snowball Earth glaciations gave multicellular eukaryotes an evolutionary advantage, paving the way for the complex organism lineages that followed. (Excerpt)

Each new level of life’s organization can be associated with an event in evolutionary history that changed the state of the evolutionary game. By adding a new hierarchical level to the organization of organisms, these major transitions in individuality added new niches to the ecosystem (e.g. trophic) and introduced new phenotypes. Such transitions include the origin of cells, eukaryotes, multicellularity, and colonial and social organisms. (1)

While each of these features plays an important role in differentiating eukaryotic and prokaryotic multicellularity, none provides a definitive answer for the 1.5 billion year gap between eukaryogenesis and the emergence of complex multicellular lineages. The Neoproterozoic Snowball Earth glacial events provide an environmental driver that our models show would have selected for multicellular morphologies during this time period, helping explain the lag between eukaryogenesis and the proliferation of complex multicellularity. (9)

Dewel, Ruth Ann. Colonial Origin for Eumetazoa: Major Morphological Transitions and the Origin of Bilaterian Complexity. Journal of Morphology. 243/1, 2000. A contribution to the 21st century project to reread and reconstitute evolution as informed by comparative, integrative and complexity concepts. A persistent process is described whereby entities such as microbes, cells or organisms evolve into integral assemblies or colonies. An increased complexity emerges as these stages form a nested hierarchy. Salient trends include a specialization or division of labor, the formation of modular components and the subsequent coalescence of further levels of organic organization. And at each transition, the rudimentary colony is said to be engaged in a task of individuation.

Duclos, Kevin, et al. Investigating the Evolution and Development of Biological Complexity under the Framework of Epigenetics. Evolution & Development. Online July, 2019. University of Calgary cell biologists contribute to this nonlinear revolution, while it goes on largely unawares, to reinterpret life’s gestation by way of innate, iterative, scalar topologies and source forces. Here the recent expansion of genomic activity to include influences beyond nucleotides, aka epigenetics broadly conceived, is applied as one more generative factor at work in evolutionary developments.

Biological complexity is a key component of evolvability, yet its study has been hampered by a focus on evolutionary trends of complexification and inconsistent definitions. Here, we demonstrate the utility of bringing complexity into the framework of epigenetics to better investigate its utility as a concept in evolutionary biology. We first analyze the existing metrics of complexity and explore its link with adaptation and developmental mechanisms. We then consider how epigenetics shapes developmental and evolutionary trajectories. We argue that epigenetics itself could have emerged from complexity because of a need to self‐regulate. Our goal is not to explain trends in biological complexity but to help develop and elucidate novel questions in the investigation of biological complexity and its evolution. (Abstract excerpt)

Eldredge, Niles. The Pattern of Evolution. New York: Freeman, 1998. The American Museum of Natural History curator argues for a broader theory that goes beyond “internalized competition between genes” to recognize hierarchical scales with a law-like continuity with the physical environment.

Fenchel, Tom. The Origin and Early Evolution of Life. Oxford: Oxford University Press, 2002. A basic text which relates the updated version of a sequential repetition of the occurrence and assembly of modular components into higher level entities.

Our ideas about evolution of life imply the integration of self-replicating molecules into a genome, horizontal transfer of genes form one individual to another, that the origin of eukaryotic cells implied the integration of endosymbiotic bacteria, and that multicellular organisms arose from cell colonies. (2)

Fernandez-Valverde, Selene, et al. Inference of Developmental Gene Regulatory Networks Beyond Classical Systems: New Approaches in the Post-genomic Era. Integrative and Comparative Biology. 58/4, 2018. The entry by research biologists from Mexico and Chile within a Genomic, Ecological and Paleontological Insights into the Early Evolution of Animals section is a good example, after decades of isolate gene studies, of realizations that equally active interlinkages are a major complementary factor. (Once again the particulate elements need be found first before connected altogether.) For concurrent views see The Vertebrate Limb: An Evolving Complex of Self-Organizing Systems by Stuart Newman, et al below and Monostability, Bistability, Periodicity and Chaos in Gene Regulatory Networks (search Qiang Lai in GCS). We also note The Molecular Quest for the Origin of the Animal Kingdom by Jordi Paps and Oxygen and the Energetic Requirements of the First Multicellular Animals by Sally Leys and Amanda Kahn.

The advent of high-throughput sequencing technologies has revolutionized the way we understand the transformation of genetic information into morphological traits. Elucidating the network of interactions between genes that govern cell differentiation through development is one of the core challenges in genome research. These networks are known as developmental gene regulatory networks (dGRNs) and consist largely of the functional linkage between developmental control genes, cis-regulatory modules, and differentiation genes. Much progress has been made in determining these gene interactions mainly in classical model systems, including human, mouse, sea urchin, fruit fly, and worm. Here, we give a historical overview on the architecture and elucidation of the dGRNs and summarize approaches to unravel them, highlighting the range of possibilities of integrating multiple technical advances. Such new knowledge will not only lead to greater insights into the evolution of molecular mechanisms underlying cell identity and animal body plans, but also into the evolution of morphological key innovations in animals. (Abstract excerpts)

Fisher, R. M., et al. The Evolution of Multicellular Complexity: The Role of Relatedness and Environmental Constraints. Proceedings of the Royal Society B. July, 2020. University of Copenhagen bioecologists including J. J. Boomsma provide further natural properties that impelled unicell organisms to join into beneficial groupings. Their prevalence then seen to imply how often this imperative (obligate) major transition has occurred.

A major challenge in evolutionary biology has been to explain variations in multicellularity across independently evolved lineages from slime moulds to vertebrates. Social evolution theory highlights relatedness in vitally complex forms. However, there is a need to extend this perspective to relative environments. In this paper, we test (John) Bonner's 1998 hypothesis that such settings are crucial to its course, with aggregative multicellularity evolving more frequently on land and clonal multicellularity more often in water. Using a combination of scaling theory and phylogenetic comparations, we describe complex organizations across 139 species spanning 14 independent transitions to multicellularity. Our results show that physical environments impact how multicellular groups form, and thus affect the major evolutionary transition to obligate multicellularity. (Abstract)

Fisher, Roberta, et al. Group Formation, Relatedness, and the Evolution of Multicellularity. Current Biology. Online June, 2013. As the Abstract details, Roberta Fisher and Stuart West, Oxford University zoologists, and biologist Charlie Cornwallis, Lund University, Sweden, propose that if life’s propensity to form into more complex entities via wholes within wholes is set within the major transitions scale an even better understanding of how and why this happens can be gained. It is worth noticing that while this ascension is good for individuality, a sense of and referral to a causal, formative source remains elusive. So this scenario is still seen as confirmation of how natural selection acts alone.

The evolution of multicellular organisms represents one of approximately eight major evolutionary transitions that have occurred on earth. The major challenge raised by this transition is to explain why single cells should join together and become mutually dependent, in a way that leads to a more complex multicellular life form that can only replicate as a whole. It has been argued that a high genetic relatedness (r) between cells played a pivotal role in the evolutionary transition from single-celled to multicellular organisms, because it leads to reduced conflict and an alignment of interests between cells. We tested this hypothesis with a comparative study, comparing the form of multicellularity in species where groups are clonal (r = 1) to species where groups are potentially nonclonal (r ≤ 1). We found that species with clonal group formation were more likely to have undergone the major evolutionary transition to obligate multicellularity and had more cell types, a higher likelihood of sterile cells, and a trend toward higher numbers of cells in a group. More generally, our results unify the role of group formation and genetic relatedness across multiple evolutionary transitions and provide an unmistakable footprint of how natural selection has shaped the evolution of life. (Abstract)

Furusawa, Chikara and Kunihiko Kaneko. Complex Organization in Multicellularity as a Necessity in Evolution. Mark Bedau, et al, eds. Artificial Life VII. Cambridge: MIT Press,, 2001. Another theoretical contribution to intimations of a inherent evolutionary tendency toward nested levels of cellular integration.

By introducing a dynamical system model of a multicellular system, it is shown that an organism with a variety of differentiated cell types and a complex pattern emerges through cell-cell interactions even without postulating any elaborate control mechanism. Such organism is found to maintain a larger growth speed as an ensemble by achieving a cooperative use of resources than simple homogeneous cells which behave ‘selfishly.’ This suggests that the emergence of multicellular organisms with complex organization is a necessity in evolution. (103)

Galvao, Viviane, et al. Modularity Map of the Network of Human Cell Differentiation. Proceedings of the National Academy of Sciences. 107/5750, 2010. A report from researchers in Brazil, Switzerland, and CCNY as a good example of scientific progress advancing beyond its reductive phase to novel recognitions of systemwide patterns and processes, as noted by its Abstract.

Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large-scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here, we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a developed human.

We discover a dynamical law of critical branching that reveals a self-similar regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions. (5750)

Gilbert, Scott and Jessica Bolker. Homologies of Process and Modular Elements of Embryonic Construction. Journal of Experimental Zoology. 291/1, 2001. A Bauplan (archetypal body form) is invoked along with common dynamical systems which employ semi-autonomous modules for their processes of organic development.

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