The Skin of Life: the Origins
We have very recently celebrated Easter. As a matter of fact we will be living blessed Easter time till Whit Sunday, when the Holy Spirit, the Roaj, the breath of God, the Divine Wind will blow upon us all, enlighten us (hopefully)… The Divine Wind, Roaj… During the Easter Vigil, a spiritually rich celebration we encountered nature in the original four elements: Fire/Light, Earth, Water and Air. All were present in some way or another in the church and its surroundings, in the readings from the Scriptures, in us. Fire and light, water, earth and air: the essence of life, the essence of all things created. Benedict XVI, during his last Easter, through the analysis of our Creed extolled the relationship that links the Creation to God as well as us to God and the Creation. In our postmodern scientific age, the mention of these four basic elements certainly sounds old and outdated, and yet…
The Universe as we currently understand it began approximately fourteen billion years ago. It all began in a huge explosion that in a few millionths of a second defined the nature of all things to be. This unfathomable release of energy could have resulted in nothing if the original reactions and processes that took place were only minutely different. This in itself is a miracle. Probabilistically, the chances that this huge explosion resulted in what we now call the universe were scant, and yet it worked. Energy, of which visible light is but a very small portion, began to cool and condense, first into elementary particles and later electrons, protons and neutrons. Further along the way during those primeval seconds and minutes, the earliest forms of matter (and anti-matter) began to appear. It would take more than a billion years for the first proto-galaxies to appear resulting from the coalescence of the primordial matter soup. Incidentally, one of the leading proponents of what became known as the Big Bang Theory, back in the early 1920s, was the Belgian Jesuit priest and physicist Georges Lemaitre. Energy-light-matter and faith…
Our Sun only made its appearance less than seven billion years ago, and our Earth appeared somewhere between six and five billion years ago. This very hot, extremely volcanically active ball of matter slowly began to cool down. Plate tectonics would change many times over its topography. It is not yet clear where water came from. May be some of it was already present in the original matter. Maybe some came from meteorites crashing on the planet´s surface, and maybe some came from comets´ trails pulled in by Earth´s gravity. All that we can be certain is that water remains a scant resource even on this blue planet (more on this in future blogs). The primordial atmosphere was most probably composed by hydrogen and helium, which gassed out from the cooling surface of the planet. This atmosphere did not last long. The Earth did not yet have a strong magnetic field creating an electromagnetic shield about the planet, and hence the strong electromagnetic solar wind rapidly blew it away… The second atmosphere contained somewhat heavier gases produced by the extensive and intense volcanic activity present in the very young Earth. As can be observed in neighbouring Venus, this atmosphere was probably rich in carbon dioxide and nitrogen. The extreme atmospheric pressure, again similar to that observed on Venus, probably resulted in an extremely hot atmosphere which nevertheless allowed the condensation of water. As water collected slowly in the future ocean basins, the very rich carbon dioxide atmosphere resulted in acidic seas. The presence of various mineral salts contributed to these primordial oceans that gave rise to basic forms of life, somewhere between four and three and a half billion years ago. So far so good: nothing makes Earth much different from the rest of the neighbouring planets.
As carbon dioxide continued to dissolve in the water and as life began to appear, carbonate deposits began to grow under the seas, effectively removing it from the atmosphere and the oceans. The atmosphere became primordially nitrogen, temperatures decreased and water condensed into the oceans more rapidly, contributing to a slow reduction in acidity. Somewhere along the line, some way or other, life began in those acidic, salty waters. And that did not occur near the surface. Because the second atmosphere did not prevent the penetration of most of the dangerous solar radiation (ultraviolet to x-rays) primordial live could not even get within one or two meters of the ocean surface. Even within that thin surface layer, such radiation would dissociate and sterilize the primitive forms of live.
Then something odd happened. The first primordial forms of cellular life, the cyano-bacteria “invented” photosynthesis, some three and a half billion years ago. At first the residue of this energy producing biochemical process began to accumulate in the oceans. The residue was oxygen. Some two and a half billion years ago iron oxide deposits began to grow under the seas. Mineral oxides in large quantities appear to be a peculiarity of our planet, as the original anaerobic, oxygen producing life continued to develop. This went one for some hundred million years or so until very few minerals that could be oxidized remained in the oceans. Thus oxygen was available to flow from the oceans into the atmosphere. This was a major catastrophe for primordial anaerobic life: the Great Oxygenation Event changed everything.
Slowly oxygen continued to collect in the atmosphere until it reached values close to 21% in the atmosphere some five hundred million years ago. Twenty one percent oxygen is a true oddity in our solar system. Venus only has traces of oxygen in its atmosphere, while in the Mars atmosphere oxygen only accounts for 0.13% of its composition… Meanwhile plant and animal life developed in oceans and other water expanses. Solar radiation continued to sterilize the surface for almost two billion years more. The oxygen present in the atmosphere began to form the ozone layer, shielding the most dangerous UV radiation. The magnetic fields that developed earlier had already provided an electromagnetic shield that protected this third atmosphere from the solar wind. At the same time, what we call weather, climate and the water cycle evolved, shaping the surface of the Earth as much as plate tectonics and vulcanism.
When the ozone layer reached values close to present ones, life virtually jumped from the oceans onto the surface, rapidly colonizing it, first with plants, which completed and stabilized the atmospheric oxygen content. Then animals followed. Life became a major force shaping the surface of the planet, regulating the atmosphere, the climate system and the water cycle, soil formation and erosion… The geophysics of the planet was now closely intertwined with life. Earth definetely became a unique place, at least in the corner of the Universe. Life created the conditions for further life. Life created a special atmosphere, its own “skin”, the skin of life.
Energy-light, water, air, matter, the Roaj, all brought together in life and with life. Maybe, after all, and despite all the refinements of our current scientific understanding such basic principles present in the Easter liturgy are not that far away from reality. Christ´s Resurrection once more renews this world both materially and spiritually (Colossians 1, 15-20).
Written by Dr. Pablo Canziani, a GCCM founding member, Investigador Principal CONICET (Senior Scientist, Argentine Research Council) and member of the Board of the Lay Department of the Argentine Conference of Bishops.