The Gaia hypothesis implies that once established, alien life will flourish.
Can the planet be alive? This is exactly what Lynn Margulis, an outstanding biologist of the late 20th century, with a brilliant intellect and an adherent of an unconventional approach, believed. Together with chemist James Lovelock, she viewed life as a planet-changing phenomenon, and considered the distinction between "living" and "inanimate" not as pronounced as is commonly believed. Many members of the scientific community ridiculed their theory, dubbed the Gaia Hypothesis, as pseudoscientific and questioned their reputation. But now Margulis and Lovelock can take revenge. Recent scientific discoveries give grounds to take their hypothesis more seriously. It is based on the concept of the relationship between planets and living organisms, which has changed our understanding of both of these concepts and shapes our understanding of other worlds.
Studying together the biosphere of the Earth, Margulis and Lovelock came to the conclusion that it has some properties inherent in living beings. This seems to indicate "homeostasis", that is, self-regulation. Many of our planet's life-sustaining abilities are remarkably robust. The range of climatic temperatures, oxygen content in the atmosphere, as well as the acidity, chemical composition and salinity of the ocean are all biologically mediated and remain in a habitable range, despite the past hundreds of millions of years. Margulis and Lovelock suggested that the entire set of living organisms is in close interaction with the environment by regulating these global characteristics. They recognized the fact that the Earth is, in a sense, a living organism. Lovelock called this the "Gaia phenomenon."
Earth and life have evolved and continue to evolve together.
Margulis and Lovelock have shown insufficient validity of Darwin's picture of biological evolution. Darwin, having identified the mechanism by which living organisms adapt to changes in the environment, made us understand that life on Earth is a continuous process, growth and reproduction, as well as the transmission of genes from a common root. From Darwin's point of view, the Earth was a kind of stage with changing scenery to which life had to adapt. But who changed the scenery? Or what? Margulis and Lovelock suggested that planet Earth is not dead, but is an animate part of a larger entity, consisting of the biosphere and "inanimate" matters that shape the biota of the Earth, are responsible for it and pass through it cyclically. Yes, life adapts to changes in the environment and is shaped by natural selection,but it also opposes the environment, changing it, and the planet itself. Now this is as obvious as the oxygen-filled air we breathe. Thus, evolution is not a series of attempts to adapt to inanimate events, but a system of responses and exchange. Life did not just adjust to the dynamically changing appearance of the planet. Most likely, there was a mutual formation of living organisms and the Earth in the process of their joint evolution. If you look at the planet from this perspective, you will see that everything - coral reefs, limestone cliffs, estuaries, swamps and cave guano islands - are part of this larger living entity. You will understand that both the surface and the interior of the Earth are alive.that we breathe. Thus, evolution is not a series of attempts to adapt to inanimate events, but a system of responses and exchange. Life did not just adjust to the dynamically changing appearance of the planet. Most likely, there was a mutual formation of living organisms and the Earth in the process of their joint evolution. If you look at the planet from this perspective, you will see that everything - coral reefs, limestone cliffs, estuaries, swamps and cave guano islands - are part of this larger living entity. You will understand that both the surface and the interior of the Earth are alive.that we breathe. Thus, evolution is not a series of attempts to adapt to inanimate events, but a system of responses and exchange. Life did not just adjust to the dynamically changing appearance of the planet. Most likely, there was a mutual formation of living organisms and the Earth in the process of their joint evolution. If you look at the planet from this perspective, you will see that everything - coral reefs, limestone cliffs, estuaries, swamps and cave guano islands - are part of this larger living entity. You will understand that both the surface and the interior of the Earth are alive.there was a mutual formation of living organisms and the Earth in the process of their joint evolution. If you look at the planet from this perspective, you will see that everything - coral reefs, limestone cliffs, estuaries, swamps and cave guano islands - are part of this larger living entity. You will understand that both the surface and the interior of the Earth are alive.there was a mutual formation of living organisms and the Earth in the process of their joint evolution. If you look at the planet from this perspective, you will see that everything - coral reefs, limestone cliffs, estuaries, swamps and cave guano islands - are part of this larger living entity. You will understand that both the surface and the interior of the Earth are alive.
The Gaia hypothesis is accepted both before and now very cautiously and not completely. There are a number of reasons for this. One is the usual inertia, the standard conservative unwillingness to accept a new way of thinking. Moreover, the theory was considered vague and vague. Some have complained about the inability of its adherents to present outstanding, well-founded, experimentally testable judgments. How can you evaluate, contrast, or accept an idea that lacks clear clarity or that is perceived differently by different people? There is certainly some truth in this. Gaia's theory has been formulated in various ways. It didn’t help that Margulis and Lovelock tried to mix science with philosophy and poetry and didn’t mind contradictions at all; I would say they liked it.
The truth is, despite its so widespread name, the Gaia Principle is not entirely a hypothesis. This is a perspective, an approach, within the framework of which scientific research is conducted about life on a living planet, and not just the one on which there is life - this is the main idea, simple but deep. Because life is not a minor trifle that has arisen on the already functioning planet Earth, but an integral part of its evolution and characteristics. Over the past several decades, the Gaia theorists have already achieved near victory. In fact, the opposition never gave up and did not admit defeat, but mainstream earth science lost ground and joined forces with chemistry, climatology, theoretical biology and some other fields of knowledge and renamed itself "earth system science".
Gaia's approach, spurred by a cosmic comparison of Earth with its supposedly lifeless neighbors, has led to a deeper understanding of how much our planet has changed under the influence of its inhabitants. Comparing the life history of the Earth with its brothers, we see that at the earliest stages of its development, the Earth began to develop along a different path. From that moment on, the planet and living organisms began their joint development.
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Having studied the Earth using modern instruments, seeing it entirely from a distance, drilling wells on the ocean floor and displaying the global biochemical cycles of elements, nutrients and energy with the help of "magic glasses" generating multispectral images, we found out that the impact of life on the planet is more complex and a more comprehensive process than we could have imagined.
Oxygen, which we take for granted, is a byproduct of organisms that interferes with the planet's geochemical cycles: harvesting solar energy to break down water molecules, storing hydrogen atoms, and reacting with CO2 to produce organic food. In the upper layers of the Earth's atmosphere, part of this oxygen is converted by ultraviolet light into the ozone layer, which serves as a shield for the planet from the harmful effects of ultraviolet radiation, making its surface habitable. The emergence of this protective layer was followed by the release of life from the ocean and the emergence of forests on the continents. This made the once lifeless continents suitable for the existence of living organisms.
The more we look through the prism of Gaia's theory, the more we realize that virtually every component of our planet has been biologically distorted beyond recognition. The earth's rocks contain over 4,000 different minerals (the crystalline molecules that make up rocks). This variety of minerals is greater than has been found on other planets until now. Geochemists studying the history of the Earth's mineral resources have come to the conclusion that most rocks could not exist without the presence of life on our planet. Thus, it was living organisms that changed the surface of the Earth, and mineral rocks are a by-product of their vital activity. A big leap in their diversity occurred after living organisms filled the Earth's atmosphere with oxygen, which led to an abundance of oxidized minerals.which painted deposits all over the Earth in bright colors. On some distant planet, such a vast and variegated variety of minerals could mean the presence of life on it, which is a potential biosignature that we can add to Lovelock's sign of atmospheric gases knocked out of balance by living organisms. Thus, minerals and living organisms nourished each other from the very beginning. There is even more evidence that minerals were critical catalysts and substrates for the origins of life on Earth. But is this really a reason to consider the mineral surface of the Earth as part of the global living system?which is a potential biosignature that we can add to Lovelock's signature of atmospheric gases knocked out of balance by living organisms. Thus, minerals and living organisms nourished each other from the very beginning. There is even more evidence that minerals were critical catalysts and substrates for the origins of life on Earth. But is this really a reason to consider the mineral surface of the Earth as part of the global living system?which is a potential biosignature that we can add to Lovelock's signature of atmospheric gases knocked out of balance by living organisms. Thus, minerals and living organisms nourished each other from the very beginning. There is even more evidence that minerals were critical catalysts and substrates for the origins of life on Earth. But is this really a reason to consider the mineral surface of the Earth as part of the global living system?that minerals were badly needed catalysts and substrates for the origin of life on Earth. But is this really a reason to consider the mineral surface of the Earth as part of the global living system?that minerals were badly needed catalysts and substrates for the origin of life on Earth. But is this really a reason to consider the mineral surface of the Earth as part of the global living system?
What about plate tectonics and the dynamics of the Earth's interior? At first glance, this sounds like a giant mechanical system - a heat engine - that does not depend on biology, but, fortunately for life, supports it. In addition, although we are not fully aware of the deep elements of the Earth's biosphere, the likelihood that living organisms exist at a depth of more than a couple of miles is rather small due to extremely high temperatures, and therefore unacceptable for organic molecules. However, we know that life reached the upper layers of the earth's atmosphere and created the ozone layer that allowed the biosphere to cover the continents, and now we are observing its influence on the deep underground spheres. Throughout its long life, Gaia's superorganism influenced not only the surface itself, but also the processes inside the planet,extracting hydrocarbon from the mantle and leaving it on the surface in sedimentary rocks, as well as sequestering huge amounts of nitrogen from the air into ammonia deposited in crystals of mineral rocks of the mantle.
Life itself, once begun, can make or keep the planet livable. By regulating the chemical state of the atmosphere, life has also altered the rocks that come into contact with it, oxygenating the earth's crust and mantle. This changed the material properties of rocks, the way they bend and break, flatten, bend, and melt under various forces and conditions. All the clay minerals produced by the Earth's biosphere have softened its crust (the crust of a lifeless planet is harder), helping lubricate the tectonic plate engine. The moisture content of the Earth explains why plate tectonics survived here rather than on drier Venus. One of the more extreme claims of the Gaia adherents, currently neither proven nor disproved, is thatthat over billions of years the influence of life helps the Earth to retain life-giving moisture, while Venus and Mars lost their lifeless most of their existence. In such a case, the presence of life may indeed be responsible for the tectonics of the Earth's plates. One of the founders of plate tectonics Norm Sleep from Stanford is fully convinced that life is deeply involved in the general physical dynamics of the Earth, including its "non-living" interior. In describing the cumulative long-term effects on geology, continental building, and plate tectonics, he wrote that “the end result is the Gaia principle. That is, life has changed the Earth in its favor. " The more we study the planet, the more we see it. Life has a stranglehold on the Earth. Earth is a planet biologically modeled to the core. In other words, alive.
Now, 40 years after the Viking landed on Mars, we have learned that the planets have a common origin, including those that are similar in size to Earth and located at an acceptable distance from their star for oceans of liquid water. In addition, Lovelock's radical idea of paying attention to the atmosphere and looking for radical deviations from the usual mixture of gases is currently the cornerstone of our strategy for detecting life on other planets. The thinking of the adherents of the Gaia theory crept into our ideas about the evolution and habitability of exoplanets, forcing us to reconsider the concept of the "habitable zone". We understand that it is impossible to draw conclusions about the suitability of a planet for the development of life on it only on the basis of its basic physical characteristics, size and distance from its star. Life itself, just begun,can make or keep the planet habitable. Perhaps, in some cases, life can destroy the habitability of the planet, as nearly happened on Earth during the "Great Oxygenation" (sometimes called the oxygen catastrophe) 2.1 billion years ago. As my colleague Colin Goldblatt, a smart young climate modeller at the University of Victoria, once said, “The defining characteristic of the Earth is life on a planetary scale. The earth teaches us that habitability and the existence of life are inseparable concepts. "A savvy young climate modeler at the University of Victoria, “The defining characteristic of the Earth is life on a planetary scale. The earth teaches us that habitability and the existence of life are inseparable concepts. "A savvy young climate modeler at the University of Victoria, “The defining characteristic of the Earth is life on a planetary scale. The earth teaches us that habitability and the existence of life are inseparable concepts."
In my book Lonely Planets (2003), I described what I call the “Living Worlds Hypothesis” based on the Gaia principle as applied to astrobiology. Life is probably a planetary phenomenon with a cosmological life cycle - in other words, life span is measured in billions of years, that is, the same time frame that determines the life of planets, stars and the Universe itself.
Organisms and species do not have cosmological life cycles, but the Gaia phenomenon does, and this, perhaps, is a common property of living worlds. Influenced by the beliefs of Lovelock and Margulis, I argued that we are unlikely to find life on the surface of a planet with an unaltered atmosphere. According to this idea, the planet cannot be "just a little alive" (as neither can man, at least for a long time), therefore such old planets as Mars, in the absence of obvious life, are probably completely dead. If the small methane emissions recently recorded by the Curiosity rover turn out to be signs of islands of Martian life on a considered dead planet, this will prove the inconsistency of my hypothesis of "living worlds" and the possibility of life manifesting in forms different from the ideas of the adherents of the Gaia theory. But the living world may need morethan just small temporary deposits of water and energy that certainly exist beneath the surface of Mars. It may require continuous geological activity from within. I believe that only in a geological sense, a "living" planet will be "alive" in a biological one. On Mars, life might never have been able to establish itself as a permanent element without plate tectonics, as well as such deep and powerful global biogeochemical cycles as on Earth.as well as such deep and powerful global biogeochemical cycles as on Earth.as well as such deep and powerful global biogeochemical cycles as on Earth.
As far as we can tell, around the time life originated on Earth, Venus and Mars had similar characteristics for triggering the process of life emerging: both had water, rocky surfaces, a thick atmosphere and intense geological activity. Comparative planetary science tells us that the conditions necessary for life to arise may be the norm for rocky planets. There is a real possibility that life also arose on Mars or Venus, but could not take root and become an integral permanent feature of the planets, as it happened on Earth. You can unite them as planets on which life was born, but which could not create a reliable and self-sufficient biosphere. Speaking of Earth, it is truly rare and unusual that favorable conditions for life have been maintained for billions of years. Maybe,it's more than luck.
If you think of the planets not as objects or places where living beings may or may not be present, but as living or inanimate entities, you can change the idea of the origin of life. Perhaps life is something that does not happen ON the planet, but WITH the planet: this is what the planet becomes.
Think of life in terms of fire. If you've ever tried to start a fire, you know that sparking and getting a flame is easy, but difficult to maintain. First you need to blow on the fire until dizziness to supply it with oxygen, or it will simply go out. Preventing the fire from extinguishing until it is well lit is always a difficult task. Then the tipping point is reached and the fire begins to rage. Thanks to the hot coals, the heat maintains its own circulation, drawing in oxygen and fanning the flame. Now that the fire is on its own, you can go have a beer and watch the shooting stars.
I wonder if the first life on the planet is similar to the first sparks and flickering flames of a fanning flame? In the earliest stages, life can be extremely vulnerable, and the moment may come when, having become a planetary phenomenon and becoming part of the global currents that support and nourish it, it will act in the opposite direction like a self-sustaining fire that not only provides itself with an influx of air, but also replenishes fuel supplies himself. The mature biosphere seems to create the conditions for the preservation and prosperity of life.
Life is something that does not happen ON the planet, but with the planet.
The perspective of "living worlds" implies that in billions of years life will either disappear from the planet altogether, or, like on Earth, will take root and become an integral part of all global processes. The signs of life will be present everywhere. Once on a planet and becoming a planetary phenomenon (a global organism, if you will), it can be very difficult to destroy it. Of course, the Earth has undergone many changes, some of which were quite traumatic. Life on our planet is unusually stable and continuous, and sometimes it even seems immortal. Call it quasi-immortality, because the planet will not exist forever, just as it may not preserve its habitability. The presence of people is just a moment. Whole species appear and disappear, and the duration of their existence, as a rule,hardly enough to attract the attention of the planet. And yet, in the complex, life is preserved. This creates a new perspective on ourselves. The Scientific Revolution has shown us, as individuals, how incredibly tiny and ephemeral we are, and that our existence, not only as individuals, but also as a species is brief and insignificant in the temporal context of cosmic evolution. If, however, we identify ourselves with the biosphere, then as part of a superorganism we have been present here for perhaps three billion years out of the thirteen that the universe is believed to exist, that is, a quarter of the time. And this is already something.and that our existence, not only as individuals, but also as a species, is brief and insignificant in the temporal context of cosmic evolution. If, however, we identify with the biosphere, then as part of the superorganism we were present here for perhaps three billion years out of the thirteen that the universe is believed to exist, that is, a quarter of the time. And this is already something.and that our existence, not only as individuals, but also as a species, is brief and insignificant in the temporal context of cosmic evolution. If, however, we identify with the biosphere, then as part of the superorganism we were present here for perhaps three billion years out of the thirteen that the universe is believed to exist, that is, a quarter of the time. And this is already something.
The origin of life on Earth was not only the beginning of the evolution of species and a storehouse of diversity, thanks to which algae bloomed, aspen groves, barrier reefs, walrus and gorilla rookeries appeared. From the point of view of planetary evolution, this development became a major branching point that opened the door to a fundamentally different future. But when life spread and deepened, planet Earth and her sisters went their separate ways.
And more recently, on this biologically altered Earth, new changes suddenly appeared, which began to rewrite the rules of planetary evolution. On the unlit side of the Earth, a light comes on, indicating something new is emerging, and it's already there. Maybe another door opened? Could the planet be at a new branch point?
The view from space sheds light on the many rapid changes that our industrial society has inscribed in the history of the planet. The orbital technology that enables such observations is itself one of the bizarre and startling aspects of Earth's rebirth. If ubiquitous life has been its defining characteristic so far, what about the lights that are lit all over the planet? Could this vast network of light become part of a new defining characteristic?
David Grinspoon is a senior research fellow at the Institute of Planetary Science and a member of teams working on several active and future interplanetary travel. In 2013, he was appointed Head of the Department of Astrobiology at the Library of Congress. His latest book, Earth in the Hands of Man, hit the shelves in December. Musician, guitarist of the House Band of the Universe.