III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet, Incubator Lifescape

3. Earth Alive: A Cellular GaiaSphere Sustains Her (His) Own Viability

Stueken, Eva, et al. Did Life Originate from a Global Chemical Reactor? Geobiology. 11/2, 2013. As “bioinformatics meets geochemistry,” astrobiologists from the University of Washington, McGill University, and NASA Exobiology, including William Brazelton and John Baross, describe an early earth scenario that seems primed and favorable for living systems to rise and prosper. Main prerequisites are: energy, organic carbon compound synthesis, catalysis, concentration, magma-hydrothermalism, metamorphic terrains, and more, as if an innate incubator.

Many decades of experimental and theoretical research on the origin of life have yielded important discoveries regarding the chemical and physical conditions under which organic compounds can be synthesized and polymerized. However, such conditions often seem mutually exclusive, because they are rarely encountered in a single environmental setting. As such, no convincing models explain how living cells formed from abiotic constituents. Here, we propose a new approach that considers the origin of life within the global context of the Hadean Earth. We review previous ideas and synthesize them in four central hypotheses: (i) Multiple microenvironments contributed to the building blocks of life, and these niches were not necessarily inhabitable by the first organisms; (ii) Mineral catalysts were the backbone of prebiotic reaction networks that led to modern metabolism; (iii) Multiple local and global transport processes were essential for linking reactions occurring in separate locations; (iv) Global diversity and local selection of reactants and products provided mechanisms for the generation of most of the diverse building blocks necessary for life. We conclude that no single environmental setting can offer enough chemical and physical diversity for life to originate. Instead, any plausible model for the origin of life must acknowledge the geological complexity and diversity of the Hadean Earth. (Abstract)

Envisioning the origin of life in a global context is advantageous because it makes prebiotic chemistry more plausible and because the global context is an inescapable reality. Origin of life research is often discussed in terms of a dichotomy: productive chemical reactions vs. environmental relevance. We have argued that thinking about prebiotic processes in a global context eliminates the dichotomy and opens the possibility that the relevant chemical reactions are also the most productive. (119)

Stueken, Eva, et al. Mission to Planet Earth: The First Two Billion Years. Space Science Reviews. 216/Art. 31, 2020. As if some global cognitive faculty has landed on this world and is retrospectively trying to learn how it all came to be, nine astroscientists with postings in Scotland, Austria, Germany, Japan, and the USA, including Helmut Lammer discuss features such as From Magma to a Water Ocean, Onset of Plate tectonics, and more.

Solar radiation and geological processes over the early million years of Earth’s history, along with the origin of life, steered our planet towards a long evolutionary course of habitability and the emergence of complex life. Crucial aspects included: (1) the redox state and volatile content of Earth’s geology, (2) the timescale of atmospheric oxygenation; (3) the origin of autotrophy, biological N2 fixation, and oxygenic photosynthesis; (4) strong stellar UV radiation on the early Earth, and (5) photochemical effects on Earth’s sulfur cycle. The early Earth presents as an exoplanet analogue that can be explored through the existing rock record, allowing us to identify atmospheric signatures diagnostic of biological metabolisms that may be detectable on other inhabited planets with next-generation telescopes. (Abstract excerpt)

Tamura, Yoshihiko, et al. Advent of Continents: A New Hypothesis. Nature Scientific Reports. 6/33517, 2016. The entry reports three papers over ten years that quantify how unique is our planetary mantle of one-third mobile land forms amidst oceans over the crustal sphere beneath. This 2016 lead from the Japan Agency for Marine-Earth Science and Technology cites a latest version. Formation and Evolution of the Continental Crust by the University of Grenoble geoscientist Nicholas Arndt in Geochemical Perspectives (2/3, 2013) is an 130 page essay fully available online. And thirdly, Evolution of the Continental Crust by the British earth scientists C. Hawkesworth and A. Kemp in Nature (443/811, 2006).

The straightforward but unexpected relationship presented here relates crustal thickness to magma type in the Izu-Ogasawara (Bonin) and Aleutian oceanic arcs. Volcanoes along the southern segment of the Izu-Ogasawara arc and the western Aleutian arc (west of Adak) are underlain by thin crust (10–20 km). In contrast those along the northern segment of the Izu-Ogasawara arc and eastern Aleutian arc are underlain by crust ~35 km thick. According to the hypothesis presented here, rising mantle diapirs stall near the base of the oceanic crust at depths controlled by the thickness of the overlying crust. Where the crust is thin, melting occurs at relatively low pressures in the mantle wedge producing andesitic magmas. The implications of this hypothesis are: (1) the rate of continental crust accumulation, which is andesitic in composition, would have been greatest soon after subduction initiated on Earth, when most crust was thin; and (2) most andesite magmas erupted on continental crust could be recycled from “primary” andesite originally produced in oceanic arcs. (Tamura)

In the Archean, like now, the granitoids that constitute the core of the continental crust formed in subduction zones. Hydrous basaltic magmas from the mantle wedge rose to the base of the crust where they fractionally crystallised or remelted underplated rocks to yield more evolved granitic magmas. From the end of the Archean to the late Proterozoic, the continental crust grew in a series of major pulses, each triggered by accelerated mantle convection. The arrival of large mantle plumes displaced material from the upper mantle, accelerating the rate of subduction and causing a pulse of crustal growth. The Hadean crust was mafic and it underwent internal partial melting to produce the granitic melts that crystallised the Jack Hills zircons. This crust was disrupted by the Late Heavy Bombardment and from then on, since about 3.9 Ga, plate tectonics has operated. (Arndt)

The continental crust covers nearly a third of the Earth's surface. It is buoyant—being less dense than the crust under the surrounding oceans—and is compositionally evolved, dominating the Earth's budget for those elements that preferentially partition into silicate liquid during mantle melting. Models for the differentiation of the continental crust can provide insights into how and when it was formed, and can be used to show that the composition of the basaltic protolith to the continental crust is similar to that of the average lower crust. From the late Archaean to late Proterozoic eras (some 3–1 billion years ago), much of the continental crust appears to have been generated in pulses of relatively rapid growth. Reconciling the sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record. (Hawkesworth)

Taylor, Stuart Ross and Scott McLennan. Planetary Crusts: Their Composition, Origin and Evolution. Cambridge: Cambridge University Press, 2009. With the burst of exoearth findings expanding and invigorating such studies, geologists from the Australian National University, and SUNY Stony Brook, here consider the wide range of coalesced, frozen surfaces around the fluid cores of orbital objects. Where are we anyway?

Van der Gulik, Peter. On the Origin of Sequence. Life. 5/1629, 2015. A Centrum Wiskunde & Informatica (Netherlands mathematics and computer science institute) systems biologist focuses on the appearance of peptide biochemicals, which are short chains of amino acid monomers linked by amine bonds. Their vital occasion on Earth is facilitated by three coordinate aspects: mineralogical composition (re Robert Hazen), a large, close Moon, and suitable ocean, atmosphere and continent environment. This unique concatenation is then taken to imply that a similar origin and complex evolution anywhere else is a rare improbability. Further requirements such as feedback loops, lipid membranes, binary codes, error robustness and metabolisms increase the odds. The result is another 2015 surmise that while cosmic physics and chemistry have deep propensities to generate living, evolving systems, we may conclude that “Earth is a very special planet.”

This study is not the first to point out that enthusiasm about extraterrestrial life is misplaced when all that is found is a simple compound. Fluid water is very special, but our beautiful Earth-Moon-Double-Planet-System has more aspects that are special. The Earth-Moon-Double-Planet-System is a rare oasis in a barren Universe. Since Pasteur, we no longer believe that mice or bacteria can very easily develop from just dead dirt. The present review has tried to point out what it is exactly which makes living organisms so special. It has been argued that from a very early stage in prebiotic/biotic evolution, a feedback loop has been in existence in which peptides and RNA were both involved. The circumstances which created that feedback loop (lipid presence among them) might have been very rare on the scale of the Universe. (1635)

Vanhoenacker, Mark. Digital Globes: A New Way to View the World. New York Times. January 8, 2013. An extensive report on novel technologies that allow brilliant spherical graphics of all kinds of earth system phenomena. For one example, streaming videos can be viewed of an oceanic earthquake and consequent tsunami wave as its spreads across seven seas and makes landfalls. For starters, try the National Oceanic and Atmospheric Administration NOAA “Science on a Sphere” site for some 300 datasets. Whom then might we imagine is collectively, collaboratively, accomplishing, seeing, learning, such global cognitive vista, and to then hopefully remediate wherever needed?

Vernadsky, Vladimir. Geochemistry and the Biosphere. Santa Fe, NM: Synergistic Press, 2007. The volume is the first English translation of the 1967 Russian edition of Selected Works, here translated by Olga Barash and edited by Frank Salisbury. Vernadsky (1863 - 1945), noted elsewhere, was a Renaissance person whose scientific interests over a long career ranged across nested earthly realms from strata to sentience. These essays, some technical, offer insights into his novel vision of an organic cosmos whose “living matter,” “a planetary phenomenon of cosmic character,” complexifies along with an increasing intelligence and reason, much akin to the work of his contemporary and collaborator Pierre Teilhard de Chardin. In Paris in the mid 1920’s, with Edouard Le Roy, they conceived and foresaw a further emergent stage of a worldwide cerebral faculty, the Noosphere. A friend of Leo Tolstoy, Vernadsky strongly opposed Marxist totalitarianism, which he could get away with because of his international stature.

Man is commonly referred to as an individual, freely living and moving over our planet and freely building his history. Up till now, historians, and humanitarians in general, and to some extent biologists, consciously disregarded the natural laws of the biosphere, the only terrestrial envelope where life can exist. Naturally Man cannot be separated from it. And this inseparable connection is becoming clear to us only at present. (407) In the geological history of the biosphere, a great future is opened to Man if he realizes it and does not direct his mind and work to self-destruction. (414)

Now we are going through a new geological evolutionary change of the biosphere. We are entering the noosphere. We are entering this new spontaneous geological process at a terrible time, at the time of a destructive world war. But the important thing for us is the fact that the ideals of our democracy correspond to a spontaneous geological process, to natural laws – to the noosphere. So we can look at the future with confidence. It is in our hands. We should not let it go. (417)

Vilovic, Iva, et al. Variations in climate habitability parameters and their effect on Earth's biosphere during the Phanerozoic Eon. arXiv:2308.08470. Technical University of Berlin, MPI and Gottingen University astrobiologists Iva Viloviæ, Dirk Schulze-Makuch, and René Heller post a latest, deeply sophisticated reconstructuin into better or worse phases for life's occasion. At once, an arduous trek is revealed to show how variable the course can be. We ask whom is our long emergent global knowsphere that can then retrospectively achieve this? As a philosophia witness, whatever manner of fantastic reality might we find this place to be? Might it imply an especial, Earthmost candidate?

We compiled environmental and biological properties of the Phanerozoic Eon from various data sets and did a correlation analysis to assess changes relevant to the habitability of Earth's biosphere. We showed that environmental parameters such as oxygen, global surface temperatures, runoff rates and carbon dioxide are interrelated. There were several periods with a thriving biosphere, with present day biodiversity and biomass. High oxygen contents are diagnostic of continental plant life and can provide an even more habitable environment compared to today. Beyond Earth, these results will help us to understand how environmental parameters affect extra solar biospheres and guide our search for extraterrestrial life. (Abstract)

Our study emphasizes that Earth experienced periods during which habitability parameters varied strongly throughout the Phanerozoic. A more thriving biosphere was characterized by higher oxygen levels and runoff rates, as well as moderate global surface temperatures. We found a direct correlation of oxygen content to a highly thriving biosphere and show that a high oxygen content is diagnostic of increased biomass production in the last 300 Ma when plants dominated the continents.

Volk, Tyler. Gaia’s Body. New York: Copernicus Books, 1998. An earth scientist elucidates an anatomy and physiology of the biosphere through its atmospheric, oceanic, vegetative, geological and chemical cycles and their intricate interplay.

Waltham, David. Half a Billion Years of Good Weather: Gaia or Good Luck? Astronomy & Geophysics. 48/3, 2007. Earth’s climate over the last 550 million years of the Phanerozoic era of “visible animal life” has been remarkably stable, while previous eons showed an order of magnitude of more variability. A University of London geologist finds such long consistency in accord with a biosphere which can self-maintain atmospheric conditions favorable to its flora and fauna. Also noted in Planetary Self-Selection.

Wilkinson, David. The Fundamental Processes in Ecology: A Thought Experiment on Extraterrestrial Biospheres. Biological Reviews. 78/2, 2003. In addition to a hierarchical structure from genes to Gaia, an alternative process-based approach is considered with regard to energy flow, multiple guilds, ecological hypercycles, a merging of organismal and ecological physiology and carbon sequestration.

Williams, George. The Molecular Biology of Gaia. New York: Columbia University Press, 1996. The senior evolutionary biologist in search of a theoretical synthesis of the micro and macro realms of earth life.

Is it possible to take Lovelock’s idea of geophysiology seriously and go on to suggest, just as the physiology of cells and organisms is now understood in light of the underlying biochemistry, so the workings of the planetary ecosystem will be understood in terms of the molecular details of the relevant biological processes?…What I have tried to do is raise the possibility that the Gaian idea is, at least in principle, capable of being viewed in terms with which most biologists, even those whose practice is strictly reductionist, can feel reasonably comfortable. (xi)

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