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. 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)

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)

Zahnie, Kevin and Richard Carlson. Creation of a Habitable Planet. Meadows, Victoria, et al, eds. Planetary Astrobiology. Tempe: University of Arizona Press, 2020. This opening chapter by NASA Ames and Carnegie Institution for Science astroscholars provides a local and cosmic (cosmocal) scenario by way of a deep review of the accretive formation of Hadean Earth, geochemical, metallic and energetic aspects, onto origin studies, how crucial water is, and more. A theme which runs through the volume is then noted as a growing realization that our home planet and solar array are not typical at all, but a rare, optimum occasion.

When the Copernican Principle is applied to a discussion of the origin and evolution of Earth, it suggests that the solar system should be typical, with Earth typical of orbital planets, and life evolving on Earth as typical. To date there is no evidence that any of this typecasting is true. The Anthropic Principle can lead to a very different perspective. In the known universe there are some 100 billion galaxies each containing 100 billion stars. If most stars have presumed planetary systems, we might expect on the order of 1022 planetary systems. If Earth as we know it is a near miracle that occurs once in say 1019 chances, there would still be 1000 Earths in the cosmos. (16, edits)

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