billion years – Biofera Tue, 08 Mar 2022 15:39:49 +0000 en-US hourly 1 billion years – Biofera 32 32 Microbes and nutrient cycling Tue, 08 Mar 2022 12:48:00 +0000

A nutrient cycle refers to the exchange of organic and inorganic matter in an ecosystem, resulting in the sequestration, elimination, recycling, and generation of particular substances and elements in the environment. Microbial life has long been known to play a vital role in consuming and regenerating resources in the environment on many levels and could be considered the primary tool through which nutrient cycling occurs.

Mushroom growing on the ground. Image Credit: Pratimaan/

How are nutrients recycled?

With respect to trophic levels, microorganisms are capable of being: primary producers, engaging in photosynthesis or other autotrophic processes; heterotrophic consumers who consume other microorganisms; or decomposers, breaking down dead plant and animal matter to recycle their components into nutrients. Therefore, the presence and character of microorganisms in a particular environment can directly influence the abundance of other life forms, both at micro and macro scales, by adjusting the availability and type of nutrients in the environment.

Microorganisms have populated the earth for more than 3 billion years, and thus predate the presence of animals and plants around which nutrient ecologies evolved. As discussed, microorganisms are able to obtain nutrients from the environment, using biochemical processes to generate energy. Over millions of years, these processes have shaped the Earth itself, causing and facilitating the transition of elements from forms in which they would otherwise remain forever locked into those accessible to other organisms and chemical processes, which concerns the field of geomicrobiology.

Microbial nitrogen cycle

Perhaps the best understood and most important microbial cycle network is that of nitrogen, an essential element of all living organisms and a key component of the most fundamental biomolecules such as nucleic acids.

The vast majority of nitrogen on Earth is in the form of atmospheric nitrogen, inaccessible to all but the very diverse nitrogen-fixing bacteria and archaea. These microorganisms generate ammonia from atmospheric nitrogen, which can then be used by other organisms and incorporated into their biomass. Ammonia can be oxidized to nitrate via nitrification, after which it is converted back to nitrogen gas by nitrification or anaerobic ammonium oxidation.

Microorganisms are involved in every step of nitrogen fixation, nitrification and denitrification, in some cases specializing in a particular aspect of one of these roles or performing them simultaneously. For example, some species of bacteria are able to fix nitrogen gas and denitrify at the same time, while others previously thought to exist only through nitrate oxidation have been shown to be able to survive in environments lacking nitrogen, switching to sulphide as the energy source. The source.

At least 14 novel redox reactions have been noted in the conversion of nitrogen compounds by microorganisms, spanning redox states from -3 to +5. Microorganisms use a wide variety of enzymes to carry out these reactions, and new interactions are continually being recognized.

Soil nutrients.

Soil nutrients. Image credit: Miha Creative/

Other geomicrobiological cycles

Likewise, microorganisms are involved in the biogeochemical cycle of carbon, oxygen, phosphorus, sulfur and other vital elements. While purely chemical and physical interactions between components of the atmosphere, hydrosphere and lithosphere also drive nutrient cycling on a global scale, microorganisms have played an indispensable role in the formation and maintaining the Earth as a place for life as we know it.

An example of how microorganisms have drastically shaped Earth’s environment is the Great Oxidation Event, where about 2.2 billion years ago, Earth’s atmosphere and oceans experienced a sudden and dramatic increase in oxygen concentration due to the increasing influence of photosynthetic cyanobacteria.

Previously, high concentrations of nitrogen, carbon dioxide, and carbon monoxide in the atmosphere would have generated a mildly reducing environment, then transitioning to a strongly oxidizing environment. Evidenced by the abundance of minerals containing reduced forms of metals dating from this period, and the sudden appearance of oxidized formations in the geological record.

Arsenic species in the reducing atmosphere before the event would have been largely incorporated into rock, but were strongly released into the newly oxidizing atmosphere and allowed to enter the oceans. An article by Chen et al. (2020) associates the evolution of arsenic detoxification biotools with this event, where strong selection pressure towards the development of arsenic-resistant genes would be favored. Microorganisms remain a key component of the arsenic cycle, modulating concentrations between the atmosphere, lithosphere and hydrosphere.

The references

Further reading

Plate tectonics could be the source of all life on Earth (and on alien planets too) Wed, 23 Feb 2022 21:49:20 +0000

Plate tectonic activity has been blamed for major earthquakes and tsunamis since the idea, first put forward in 1912 by meteorologist Alfred Wegener, has existed.

Subduction forces obliterated entire continents during the 3.2 billion years that plate tectonics occurred on our 4.5 billion year old Earth. The planet’s crust is sunk into the inner layers of Earth’s warm mantle, where annihilation awaits.

An illustration of the generally accepted theory of plate tectonics. New research claims that this activity led to the development of life on Earth. (stock photography)

New research argues that the source of so much destruction is also the source of life. You see, behind these apocalyptic events, there is something critical to life as we know it: researcher Rajagopal Anand argues that early Earth’s orbital patterns may have been key to making plate tectonics possible.

If we are to find habitable worlds – think of them as new Earths – we may need to consider the larger picture of cosmic planetary motion.

The idea is put forward in Anand’s research paper which has not been peer reviewed and was published this week on arXiv, a hub for “pre-print” studies that have not been published. in an academic journal.

Plate tectonics could be crucial for the formation of life on alien worlds

The tectonics of Earth’s plates depend on mass, internal viscosity contrast, availability of liquid water, and heat from the planet’s core. But the initial spin rate, in addition to our planet’s revolutionary periodicity as it moves around the sun, is crucial for plate tectonic activity to begin, Anand says.

“Earth’s initial orbital conditions were significantly influenced by the diametral processes of core segregation and moon formation, and this likely led to the possibility of the initiation and persistence of plate tectonics” , proposes the article.

With a contrast in viscosity between the planet’s layers, an intense heat source, and the availability of liquid water, the up and down motion of the mantle (called mantle convection) interacts to give motion to the plates of the rocky crust. of a planet. But for this motion to continue, the rocky body must spin on its axis and orbit its star in a specific way to reach habitable conditions.

Here on Earth, its unique orbital conditions were dramatically altered, millions of years after the formation of the solar system, when the moon appeared following a cataclysmic impact with another small planet.

Adding a term to the equation for life in the universe

This impact is believed to have accelerated the rotational speed of the Earth from its original rotational speed. And, this – in conjunction with the moon’s separation process, which is still occurring (for example, tidal forces gradually slowing Earth’s rotation) – has “far-reaching implications for the initiation of tectonics plates and the emergence of life,” writes Anand.

Plate tectonics provides essential initiators for life – a changing crust of the planet is one – and for the development of the hydrosphere and an atmosphere.

The changing shape of the crust also provides new sources and sinks for sedimentary processes that circulate nutrients for the evolution and diversity of organic life.

Researchers have found that optimal conditions of rotational and revolving periodicities are essential for the development of plate tectonics.

At least they could have been on Earth. And if so, it could help solve one of the necessary conditions for habitable conditions on alien worlds beyond our solar system.

Europa, Mars and Venus do not have the parameters of life as we know it

Europa is closely linked to its host planet, Jupiter. This relationship prevented the development of plate tectonics since the gravitational strain on the Jovian moon is uneven. In other words, it could be that Europa, despite its deep oceans, is missing one of the crucial characteristics for the evolution of organic life. At least, life as we know it.

Both Mars and Venus have all the ingredients to form long-lived radioactive isotopes, which create an additional heat source and thus mantle convection. Yet both planets are tectonically “dead with a stagnant lid,” according to the study. Things might have turned out differently for our closest planetary cousins ​​had orbital and spin velocities approached the equivalence ratio of rotational periodicity. It almost corresponds to the time it takes for the planet to move one degree in its orbit around the sun.

Earth's tectonic plates
Earth’s tectonic plates.

Expand the Parameters of Interstellar Life — Earth’s current periodicity of 365 days stacked against its rotational periodicity of 0.997 days has contributed to optimal conditions for plate tectonics. If we’re going to find another planet beyond our solar system like ours, we might have better luck looking for a match in the orbital parameters.

Other parameters, such as the distance from the Earth to the sun in relation to the size of the latter, in addition to the distance from our planet to huge gas giants, such as Jupiter, are crucial for life.

Humans must continue to work out the unknown terms of the equation that determines how, when and where life can arise on extraterrestrial worlds, if we are ever to learn, for sure, whether or not we are alone in the universe. .

Summary of the study:

The existence of plate tectonics on Earth is directly dependent on the internal viscosity contrast, the mass of the planet, the availability of liquid water, and an internal heat source. However, the initial conditions of rotational speed and revolutionary periodicity of the Earth around the Sun must also have been important for the onset of plate tectonics. Earth’s initial orbital conditions were significantly influenced by the diametral processes of core segregation and Moon formation, which likely led to the possibility of the initiation and persistence of plate tectonics. The change in orbital conditions could have caused Earth to evolve in a near-linear trend so that the planet’s rotational periodicity (TP) could approach the time taken for the planet to travel one degree in its orbit around the Sun (T1degree ) , i.e. TP ~ T1 degree. Such an optimal condition for the periodicities of rotation and revolution could be essential for the development of plate tectonics on Earth. This hypothesis has direct implications for the possibility of plate tectonics and life in extrasolar planets and potentially habitable solar planetary bodies such as Europa and Mars.

It used to be their world, now it’s yours – Red Bluff Daily News Fri, 04 Feb 2022 01:54:35 +0000

Here’s something readers probably won’t find in another Red Bluff Daily News column:

Andrew Knoll is best known for his contributions to Precambrian paleontology and biogeochemistry. He discovered microfossil records of early life around the world and was among the first to apply the principles of taphonomy and paleoecology to their interpretation.

Taphonomy is the study of how organic remains move from the biosphere to the lithosphere, and it includes processes affecting remains from the time of an organism’s death (or discarding of lost parts) through decomposition , burial and preservation in the form of mineralized or other fossils. stable biomaterials. He also elucidated the earliest records of skeletonized animals and remarkable fossils in China preserved in exceptional cellular detail by early diagenetic phosphate precipitation.

Knoll and colleagues authored the first paper demonstrating strong organic matter preserved in Neoproterozoic sedimentary rocks (1000 to 542 million years ago), and Knoll’s group also demonstrated that Middle Proterozoic carbonates display little of isotopic variation over time, unlike older, older carbonates. younger estates.

While I don’t understand much of what I just wrote, his following statement bears repeating:

“Some people now believe we are in the midst of a sixth mass extinction, and that the late Permian extinction holds lessons for the climate crisis we currently find ourselves in. As the increase current CO2 is largely due to the burning of fossil fuels, there is a very interesting resonance between the extinction patterns we see at the end of the Permian period and the kind of incipient biological effects of global warming in the 21st The study of past mass extinctions also shows that life bounces back, but it takes a very, very long time – tens of millions of years.

His book “A Brief History of the Earth: Four Billion Years in Eight Chapters” published last year ends with an eloquent call to action:

“You stand here in the physical and biological heritage of 4 billion years. Here you walk where trilobites once roamed an ancient seabed, where dinosaurs roamed gingko-clad hills, where mammoths once towered over an icy plain. It used to be their world, now it’s yours. The difference between you and the dinosaurs, of course, is that you can understand the past and envision the future. The world you inherited isn’t just yours, it’s your responsibility. What happens next is up to you.”

Changing the subject drastically, here’s an aside for today’s jazz drummers: If you watch Dave Brubeck’s drummer, Joe Morello, play drums on You Tube’s “Take Five” video, note how Joe holds the wand in his left hand between his middle and ring finger. If you, like many drummers today, hold the drumstick in your left hand palm down, you won’t have Joe’s flexibility. Sure, you’re unlikely to have his flexibility and technique, whatever, but it’s a start. However, if you are using mallets instead of conventional drumsticks, then of course both hands are used with the same overhand grip.

Joan Didion was a famous writer who died in 2021 and was married to another famous writer, John Gregory Dunne who died in 2003. As such, both received critical acclaim for their writing and were prominent in literary circles , and yet her latest novel “Play It Like It Lays” probably wouldn’t pass my Daily News editor, not only for the liberal use of the F-word, but also for the subject matter involving a fictional actress, her behavior and , in general, his deplorable lack of self-esteem. Although I am no prude, I do not understand how acclaimed novelists can be allowed, say, to publish material which, to me, seems to be unsalvageable, but then , I know the answer. Their stuff sells, and readers will agree that the writers and their subjects must therefore be acceptable. After all, they portray, apparently, a slice of life.

I mention this because the columnists of this newspaper give readers a slice of their lives every week, often with warts and all.

In my case, however, readers can vicariously experience and revel in my beautiful life. In the case of other columnists, not so much.

That said, that writes, it’s all in the eye of the beholder and did I read “Play It Like It Lays” to the end? Well, yes, but still…

“He who falls in love with himself will have no rivals.” Benjamin Franklin.

However, “Loving yourself is the start of a lifelong romance.” Oscar Wilde.

My cousin Bill in San Jose sent me some possible statements on a tee:

“Jesus loves you… but I’m his favorite”

“WC Fields said, ‘Start every day with a smile and end it. “”

“I’m so busy I don’t know if I found a rope or lost a horse”

I wrote in my Passing Parade column this week that our big dog Jazz was disheartened by the SF 49ers’ loss to the LA Rams. However, police logs this week reported that a woman’s drunken husband, angry at the loss of the Niners, had threatened to kill her dog. Excessive drinking was apparently the cause of the threat, and no dogs were involved in the outcome of the match. TTT…TTT.

A door-to-door vacuum cleaner salesman went to the first house in his new territory. A woman opened the door, but before she could say a word, he rushed inside and dumped a load of horse manure on her living room carpet.

“Ma’am,” he said in his best seller speech, “if this vacuum doesn’t do wonders cleaning up horse manure, I’m going to eat every morsel of it.”

The woman replied coldly, “Do you want ketchup on that?”

The seller was surprised and asked, “What do you mean?”

“Well, we just moved in and we haven’t turned on the electricity yet.”

Robert Minch is a longtime resident of Red Bluff, former columnist for Corning Daily Observer and Meat Industry magazine, and author of “The Knocking Pen.” as well as his new book “We Said”. He can be reached at

Study reveals more hostile conditions on Earth as life evolves Wed, 05 Jan 2022 00:00:01 +0000

Graph showing how UV radiation on Earth has changed over the past 2.4 billion years. Credit: Please credit: Gregory Cooke / Royal Society Open Science

For long parts of the past 2.4 billion years, Earth may have been more inhospitable to life than scientists previously thought, according to new computer simulations.

Using an advanced climate model, researchers now believe the level of ultraviolet (UV) radiation reaching the Earth’s surface could have been underestimated, with UV levels up to ten times higher. students.

UV radiation is emitted by the sun and can damage and destroy biologically important molecules such as proteins.

The past 2.4 billion years represent an important chapter in the development of the biosphere. Oxygen levels have risen from almost zero to significant amounts in the atmosphere, concentrations fluctuating but eventually reaching modern concentrations about 400 million years ago.

During this time, more complex multicellular organisms and animals began to colonize the earth.

Gregory Cooke, a Ph.D. researcher at the University of Leeds who led the study, said the findings raise new questions about the evolutionary impact of UV radiation, as many life forms are known to be adversely affected by intense doses of UV radiation.

He said: “We know UV rays can have disastrous effects if life is too exposed. For example, they can cause skin cancer in humans. Some organisms have effective defense mechanisms, and many can repair some of the damage caused by UV rays. .

“While high amounts of UV radiation would not prevent the emergence or evolution of life, it could have acted as selection pressure as organisms are better able to cope with larger amounts of radiation. UV receiving an advantage. ”

The research “A revised lower estimate of ozone columns during the oxygenated history of the Earth” is published today in the scientific journal Royal Society Open Science.

Une étude révèle des conditions plus hostiles sur Terre à mesure que la vie évolue

An overview of oxygen (O2) the concentrations in the Earth’s atmosphere over time are shown in this figure. Brown blocks show the estimated range for O2 compared to its current atmospheric level (which is 21% by volume). The gray-blue lines indicated various events important to the evolution of life, including the emergence of eukaryotes and animals. Black arrows refer to important events where the atmospheric oxygen concentration has changed. The Archean, Proterozoic and Phanerozoic are geological eons. GOE = Large oxidation event; NOE = neoproterozoic oxidation event; CE = Cambrian Explosion; LE = Lomagundi excursion. Credit: Please Credit: Gregory Cooke / Royal Society Open Science

The amount of UV radiation reaching Earth is limited by ozone in the atmosphere, described by researchers as “… one of the most important molecules for life” due to its role in uptake of UV radiation as it passes through the earth’s atmosphere. .

Ozone is formed as a result of sunlight and chemical reactions, and its concentration depends on the level of oxygen in the atmosphere.

For the past 40 years, scientists have believed that the ozone layer is able to protect life from harmful UV rays when the level of oxygen in the atmosphere reaches about one percent of the current atmospheric level.

The new modeling calls this assumption into question. This suggests that the level of oxygen needed may have been much higher, perhaps 5-10% of current atmospheric levels.

As a result, there have been times when UV radiation levels on the Earth’s surface were much higher, and this could have been the case for most of Earth’s history.

Mr Cooke said: “If our modeling indicates atmospheric scenarios over the oxygenated history of the Earth, then for over a billion years the Earth could have been bathed in much more intense UV radiation than it does. we did not believe it before.

“This may have had fascinating consequences for the evolution of life. It is not known precisely when the animals emerged, nor what conditions they encountered in the oceans or on land. However, depending on oxygen concentrations , animals and plants could have faced much more difficult conditions than today. We hope that the full evolutionary impact of our results can be explored in the future.

The results will also lead to new predictions for the atmospheres of exoplanets. Exoplanets are planets orbiting other stars. The presence of certain gases, including oxygen and ozone, may indicate the possibility of extraterrestrial life, and the results of this study will help scientific understanding of surface conditions on other worlds.

Ozone pollution has increased in Antarctica

More information:
A revised lower estimate of ozone columns over the oxygenated history of the Earth, Royal Society Open Science (2022). DOI: 10.1098 / rsos.211165.

Provided by the University of Leeds

Quote: Study reveals more hostile conditions on Earth as life evolves (2022, January 4) retrieved January 5, 2022 from hostile-conditions-earth-life.html

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Caterpillar and butterfly – The Ukiah Daily Journal Sun, 19 Dec 2021 17:05:13 +0000

A caterpillar is a eating machine, focused exclusively on consumption, much like a capitalist enterprise. But unlike a business, a caterpillar is a living organism, part of a larger process. At some point, it stops consuming, forms a protective chrysalis and completely dissolves, giving way to the emergence of a butterfly. The butterfly begins to form around several “imaginal buds” in the dissolved goop. The immune system of the caterpillar attacks these growing buds as enemies, which speeds up the assembly of the butterfly. A similar process may be at work within humanity.

Modern humans first appeared around 300,000 years ago, slowly increasing the population to 20 million 10,000 years ago when agriculture began. Increased food productivity allowed for faster population growth, and we reached one billion in 1800, at the start of the fossil fuel age. Then the population grew exponentially faster. Humans reached 2 billion in 1930, rising to nearly 8 billion today, with another billion over the next 12 years. Not only are there more of us, but the technological revolution has amplified our impact, so we each consume more in terms of food, resources and energy. Exponential growth on a finite planet is unsustainable. We are consuming the Earth to death.

This situation has been written, with growing concern, for decades, but like a stupid caterpillar, relentless consumption and economic growth prevailed. We are currently living at the forefront of the collapse of our fundamental biosphere.

As I write these lines, the Midwest is starting to assess the damage caused by a widespread extreme weather event, including an F5 tornado that has remained on the ground for over 200 miles, tearing the hearts of every community it has. affected. Climate change is increasingly difficult to deny, as the impact and costs increase every year. Species are disappearing at an unprecedented rate. But maybe there’s a butterfly waiting in the dissolving goop of what we used to call normal. What could this butterfly look like?

The root of the dysfunction of our old civilization is the belief in the separation between people and nature: to act as if the exclusive gain at the expense of others and nature is progress. The consequences of this flawed model are now increasingly evident around the world. This suggests an alternative: a new civilization that embraces the deep and sacred connectivity of reality, an ancient perspective still honored by indigenous cultures. If we apply the technical knowledge we have gained over the past thousands of years to feeding all life on the planet, imagine what we could accomplish!

There is no model in human history for this type of massively conscious and cooperative society, but we can take inspiration from living systems, as life has dealt with these same issues for billions of years. Getting inspiration from life is called biomimicry. Our own body, a large multicellular organism, is a wonderful example of the kind of collective that could be born on Earth: to become a self-aware planet. In such a connected system, killing the other is tantamount to committing suicide, so we could eliminate all the resources, anxiety, and energy currently spent on “defense”, and these organized systems could instead work to cleanse them. damage that we have created, improve the quality of life of all beings. In a connected world, extreme wealth inequity would be recognized as a dangerous form of disease, like gangrene in the body, and not something to be envied or praised. Mankind has grown to the point of driving all other species to extinction, disrupting the larger order in the same way obesity causes other bodily systems to fail.

This vision requires a shift within our dominant human consciousness, which may seem impossible. But this message has been taught for thousands of years. Next Saturday it is Christmas, in honor of the birth of Christ, who declared that the most important commandments were: “Love God” and “Love your neighbor as yourself” (Mark 12:30 and 31 ). It is an affirmation of the unity of life, which is found in all the spiritual traditions of the Earth.

We each have the power to choose to live from this perspective of unity. It is the butterfly that emerges. All the people who hate and work to prevent this from happening, trying to preserve the old exclusive order, are like the dying caterpillar’s immune system. But this system has disappeared. The future is the butterfly.

Crispin B. Hollinshead lives in Ukiah. This article and previous articles are available at

How LUCA, the first living being on Earth, appeared out of nowhere Sat, 04 Dec 2021 01:30:05 +0000

December 4, 2021

Pedro necklace

Update: 12/04/2021 01:25 a.m.


The study of the origin of life is a fascinating and complex field and has disturbed scientists not only out of intellectual curiosity, but also as a way forward to understand our own origins.

One of the first to address this question was the philosopher Aristotle (384 BC – 322 BC) and solved it with his theory of spontaneous generation, according to which life is generated from inert matter. This theory was not refuted until the 19th century by the French scientist Louis Pasteur.

Prebiotic chemistry

It is believed that the Earth formed exactly at the same time as the solar system, about 4.5 billion years ago now, and that for a long time there has been a continuous bombardment of meteorites, which together with the high geological activity, caused pressures generated. and temperatures so high that life was absolutely impossible.

The scenario began to change about 3.9 billion years ago when a stable hydrosphere appeared on our planet. In this liquid mass, dissolved molecules, mineral fragments and rocks appeared, as well as bubbles generated by gases expelled from underwater volcanoes.

Some four million years later, there were already different species of cells that began to “relate” to each other in a very archaic way. What made him go from an inhospitable, lifeless planet to the appearance of perfectly established living beings?

In an attempt to answer this question, in the middle of the last century, the American scientist Stanley l miller (1930-2007) carried out an experiment from which the components of the original Earth’s atmosphere (ammonia, hydrogen, methane and water vapor), with the participation of electric discharges that in some way simulated the energy contribution that existed before the appearance of life, they were able to react and produce organic compounds.

In other words, Stanley L Miller has shown that it is possible to generate basic biological molecules from simple chemical compounds.

The world of RNA

In the 1980s, it was shown and accepted that all living things originated from a single common ancestor who was baptized as LUCA – an acronym in English for “the only common universal ancestor” – and who lived about 3,500 million years ago, who carried out all the basic mechanisms of a living being.

LUCA was a nucleusless, single-celled living being with a lipid plasma membrane and a DNA genome. It is estimated that it could have around 600 genes and that bacteria, archaea and equariots have formed from it.

This is when a new question arises: what was the intermediate act between prebiotic chemistry and LUCA?

We know that proteins are encoded in DNA and that DNA replication cannot occur without the participation of active proteins.DNA polymerase‘. In a way, this pairing represents the chicken and egg paradox at the molecular level, being impossible to know if the first thing to appear in the theater of life was DNA or proteins.

Most likely it was neither, the first actor to appear on the stage had to be RNA. The explanation must be sought in that it is the only macromolecule sufficiently versatile to function as a genotype and phenotype. RNA is much more than an intermediary molecule in the flow of genetic information as has been believed for some time, since it is able to perform the functions of DNA and proteins.

Most likely, between prebiotic chemistry and LUCA there was what is now called the “RNA world”, that is, protocells with ribozymes, fatty acids in their membranes and a RNA genome.

Despite all that has been put forward in the knowledge of the origin of life, there are still many questions to be answered. For example, if RNA is a very sensitive molecule to hydrolysis, how is it possible that it was formed on a planet “overflowing” with water?

Mr. Jara

Pedro Gargantilla is an internist at the Hospital de El Escorial (Madrid) and author of several popular books.

See them


What is geomicrobiology? Tue, 23 Nov 2021 08:00:00 +0000

Geomicrobiology is the study of the role of microbes in the geological and geochemical processes that shaped the earth and continue to function today. Microbes play a vital role in the recycling, generation, sequestration and elimination of a wide variety of substances and chemicals in the environment Going through biogeochemical cycles that cover the atmosphere, hydrosphere and deep lithosphere.

Image Credit: kram-9 /

When did geomicrobiology become a field of study?

The term geomicrobiology was coined in the 1950s to describe the study of these processes, although scientists had been studying soil and aquatic microbiology since the 19th century. Christian Ehrenberg identified in 1836 that Gallionella ferruginea has been associated with the presence of iron deposits from peatlands, although at the time he misidentified this bacterium as a protozoan.

Later in 1887 Sergei Winogradsky noted that Beggiatoa bacteria could oxidize hydrogen sulfide gas to solid elemental sulfur, then in 1888 this Leptothrix ochracea bacteria has been implicated in releasing iron carbonate from rock to generate iron oxide.

The role of bacteria in precipitation of calcium and manganese in the oceans, methane formation, weathering of rocks, and the nitrogen cycle became clearer over the following decades, often preceded by the recognition of l metabolic activity of microorganisms in the laboratory and the subsequent realization of the extent that these processes played in the formation of the earth and its ecosystems.

Even in the last 20e century, the discoveries concerning the role of microorganisms in the formation of the earth were recognized. For example, it was long believed that microorganisms would be unable to survive outside a relatively narrow pH and temperature range, but the discovery of extremophilic bacteria that thrive in strongly acidic or alkaline environments around sites of mine drainage as well as identifying those who live around hot thermal vents and in frozen conditions at the poles have changed that view.

Reports that the influence of microbial life extended miles below the earth’s surface and the seabed in the 1990s and 2000s further fueled the realization that many aspects of geology previously considered entirely to be the result of physical and chemical forces were in fact due to the actions of microorganisms over millions of years.

The field of geomicrobiology had historically established that subterranean anaerobic life is organized into zones on a “thermodynamic scale”, where highly energetic iron reducers exclude sulfate reducers, which similarly exclude methane-producing microorganisms. . However, the environmental pH can alter the metabolic pathway which is the most thermodynamically favorable.

For example, under acidic conditions, iron reducers hold an additional energy advantage that is not present under alkaline conditions. In this way, certain types of microorganisms can become dominant in a particular geographic region, although long-term bioreactor experiments reveal that the three types of energy producers work in symbiosis to balance the availability of resources, rather than to compete directly.

Emerging geomicrobiology

The upper oceanic crust is continually created at mid-ocean ridges, where high-temperature basalt-seawater reactions generate energy to sustain life, with heat-generating hydrothermal currents that recycle and collect sediment. Anaerobic and aerobic microorganisms thrive in these environments and contribute to the recycling of hydrogen, carbon, and sulfur, and are believed to constitute the majority of microbial life in the oceans.

As the basalt rock is pushed back from the ridge, it cools and experiences cracking and oxidation over a period of approximately 10 million years, at which time the intensity of the basalt-seawater reactions and therefore the circulation of fluids and sediments decreases. Over 90% of the oceanic lithosphere is over 10 million years old and deficient in organic sediments and abundant in dissolved oxygen. It was therefore believed that relatively few microorganisms would live under these conditions.

In an article by Suzuki et al. (2020) Microbial cells are identified in samples of basaltic lava from the subsoil dating back more than 10 million years, living on abundant marine sediments rich in iron. Dissolved molecular oxygen has been found to penetrate the basalt rock, supporting aerobic microbes throughout the overlying sediment. Most of the microorganisms identified in these ancient basalts engage in heterotrophy and methanotrophy, feeding on dissolved organic matter brought in by seawater flows or generated by weathering of rocks.

The authors suggest that this realization could have implications for the possibility of life on Mars, whose basaltic crust formed around 4 billion years ago and was once covered with oceans like on Earth, providing a model around which astrobiologists could investigate the past existence of life on other planets.

The references:

Further reading

Hydrate or Die: Has Venus Ever Been Inhabitable? Wed, 10 Nov 2021 08:00:00 +0000

Title: Has Venus ever been habitable? Constraints of an interior-atmosphere-redox couple Evolution model

Authors: Joshua Krissansen-Totton, Jonathan J. Fortney, Francis Nimmo

Institution of the first author: University of California, Santa Cruz

Status: Published in the Planetary Science Journal [open access]

Where did the water go? (And was that there to start?)

Although sometimes referred to as “Earth’s twin,” Venus is not very similar to Earth beyond its size and composition. With an overwhelmingly toxic atmosphere filled with CO2 and a surface full of volcanoes, it’s definitely more like the Earth wrong double. Even a spaceship can only survive on its surface for no more than 2 hours before succumbing to the high pressure and temperature of a planet in the grip of the uncontrollable greenhouse effect.

But has Venus always been such a hellish place? For a long time, we hypothesized that Venus had an ocean of liquid water on its surface several billion years ago, but being closer to the Sun, an uncontrollable greenhouse effect set in: as as the Sun grew brighter over time, the more sunlight the radiation hit the surface of the planet and led to more water vapor in its atmosphere. This led to an increase in the evaporation of surface water. As the presence of water vapor warmed the planet even further, the intense radiation from the Sun split the molecules, causing hydrogen to leak into space. This left room for carbon escaping from the planet’s surface to combine with some of the remaining free oxygen and accumulate CO.2 in the atmosphere, trapping even more heat and causing an uncontrollable greenhouse effect.

Different models of Venus’ climate change have led to conflicting stories about its past. Some models that incorporate the effects of clouds responding to a warming or cooling of a planet have found that habitable conditions may have existed on the planet only 0.7 Gyr ago. In addition, unlike the Moon or the Earth, whose craters are altered or degraded, most of Venus’ craters are in perfect condition and also randomly distributed over its surface. From this, we believe that most of Venus’ geological history has been erased due to resurfacing events such as volcanic explosions and lava flows that have occurred very recently. This means that the surface we can see is very young (2). But if the water vapor in the atmosphere was broken down by radiation and most of the hydrogen escaped into space, that would mean there should be some the remains of oxygen in the atmosphere. So what happened to all the oxygen?

Let PACMAN eliminate all our doubts …

The authors of today’s article attempt to reconcile all the clues we have about Venus by using a coupled atmosphere-interior model called PACMAN (Planetary Atmosphere, Crust, and MANtle) to reproduce its climatic conditions over time in order to to see if the planet could ever have supported liquid water on its surface. All of this means that they keep track of conditions in both atmosphere and his interior while taking into account any effect one system has on the other. People have used these kinds of models to study Venus before, but none of them ever considered the possibility of having water on its surface.

The model is divided into two phases. Initially, Venus had an ocean of magma on its surface created from impacts with other pieces of space rock that were abundant during the formation of the planet. It was a giant layer of molten, sparkling rock that you definitely wouldn’t want to dip your toes into. As this ocean cooled and released gases into the atmosphere, the temperature dropped to a point where this ocean “froze” and became a solid mantle, initiating phase two of the model. The authors calculate quantities such as the surface temperature, the amount of radiation emitted and absorbed by the planet, the amount of water vapor in the atmosphere, and the amount of water at the surface during both phases. They also keep track of the abundance of various molecules containing carbon, hydrogen and oxygen (carbon dioxide, water, O2, etc.) and calculate their flux between the atmosphere and the interior (i.e. how many of these molecules enter or exit over time). In addition, they also calculate the accumulation of 40Ar and 4It in the atmosphere which tells us about total magmatic activity and more recent magmatic activity, respectively. Together, these allow us to better determine whether a habitable or uninhabitable past is better able to predict the current atmosphere of Venus.

Figure 1: A simplified diagram of the PACMAN model used by the authors. On the left is the magma-ocean phase which consists (from the innermost layer to the outermost layer) of the core, a solid mantle, the magmatic ocean and the atmosphere. On the right is the solid mantle phase that occurs after the solidification of the magmatic ocean, consisting of the core, the solid mantle, and the atmosphere / hydrosphere. Arrows in different colors indicate which components leave and enter each layer of the model. Adapted by Katya Gozman from Figure 1 of the article.

There are a lot of unknown parameters and initial conditions in the model such as CO2 pressure and planetary albedo (reflectivity), so they run their model 10,000,000 times to sample all 24 of these unknown parameters. Of all these passes, only 10% of them successfully ended in a state that reflects modern Venus atmospheric and surface conditions and chemical abundances. What’s interesting about these successful models is that they predict two different stories: some models tell us that Venus was NEVER habitable in its past, while others predict that Venus was temporarily habitable, which means that it could have contained an ocean up to ~ 100 meters deep on its surface between 0.04 and 3.5 Gyrs before succumbing to the uncontrollable greenhouse effect. This latter scenario should have left deposits of salt or minerals on the surface after all the water evaporated, leaving them potentially accessible to future remote sensing observations!

And the winner is…

So which model is correct? Unfortunately, there is no definitive answer since the authors found that one or the other model is favored under different conditions. CO2 tends to make it difficult for hydrogen to escape if the water concentration is too low. Therefore, in habitable scenarios where no surface water is present, H2The O in the atmosphere has difficulty escaping because the CO2 continually dominates the atmosphere instead of being locked in the surface. This means that these scenarios cannot recover the modern Venus without water and oxygen that we see today. But if the CO2 is allowed to radiatively cool the upper atmosphere, then water can condense on the surface and CO2 is removed from the atmosphere and stored inside the planet, giving Venus a chance to have a period of increased water loss which can then initiate the uncontrollable greenhouse effect before CO2 is degassed into the atmosphere.

On the other hand, most modern models assume that when the ocean phase of the magma ends, virtually all of the carbon and water in the magma (so called birds) live in the atmosphere. But he is possible that some of these birds are trapped in the resulting solid mantle instead. If this is allowed, then far fewer models allow Venus to have been habitable. This is because it would take longer for water to then be released into the atmosphere, making it difficult to explain Venus’ current almost non-existent abundance of water.

The bottom line here is that either of these two scenarios is possible and consistent with modern observations. The winning scenario depends on our assumptions and the parameters of the model. While it may seem a bit anticlimactic, understanding and constraining the evolution of Venus is important for interpreting the atmospheres and stories of other exoplanets that may have undergone similar processes. JWST is (fingers crossed!) Going to launch in a little over a month, and it might have the ability to constrain what are the atmospheres of other so-called exo-Venuses, such as some of the planets in the TRAPPIST system. -1. Hopefully our studies of Venus and exo-Venus can symbiotically help shed light on planetary evolution!

Astrobite edited by Ishan mishra

Featured Image Credit: NASA / JPL-Caltech

About Katya Gozman

Salvation! I am a second year doctoral student at the University of Michigan. I am originally from the northwest suburbs of Chicago and did my undergraduate studies at the University of Chicago. There, my research mainly focused on gravitational lenses and galaxies, while also focusing on machine learning and neural networks. Today I am working on galaxy mergers and stellar halos, currently studying the spiral galaxy M94. I love doing astronomy outreach and often volunteer with a STEAM education nonprofit in Wisconsin called Geneva Lake Astrophysics and STEAM.

Earth’s crust was ‘hot and thin’ across ‘boring billion’, study found Fri, 05 Nov 2021 10:42:40 +0000

It seems that the “boring billion” – a period in Earth’s history between 1,850 million and 850 million years ago – wasn’t so boring after all.

Geologists have found that our planet’s crust is “hot and thin” throughout the period, measuring only 25 miles (40 km) or less.

Today, under large mountain ranges, such as the Alps or the Sierra Nevada, the base of the earth’s crust can be as deep as 60 miles (100 km).

In addition, the relatively thin crust swirled around and was populated by a few low mountain ranges, created by milder tectonic activity.

The Boring Billion has always been considered the most boring time in Earth’s history, as little has happened to its climate, tectonic activity, or biological evolution.

The crushing of tectonic plates caused most of the Earth’s mountains to form – a process called “orogeny” – including the Himalayas (pictured). But during the Boring Billion, Earth populated by lower mountain ranges, created by milder tectonic activity


The “boring billion” is a time when the Earth’s climate was very calm.

It is believed that between 1800 and 800 million years ago, very little changed.

The most advanced life on Earth was algae, and oxygen levels were much lower than they are today.

But no serious ice age or volcanic activity is believed to have occurred, allowing the status quo to be preserved for around a billion years.

The new study, led by Christopher J. Spencer, a geologist at Queen’s University in Kingston, Canada, challenges that idea.

“During the Boring Billion in particular, oxygen levels were low and there is no evidence of glaciation,” the team says in its article, published in Geophysical research letters.

“We propose that the thin crust at this time is a product of high temperatures resulting in greater crustal flow and therefore lower mountain ranges.”

The Earth’s lithosphere – its outermost rocky shell – is made up of about 15 tectonic plates, each of different shapes and sizes.

Strong seismic activity can be detected along the boundaries of the tectonic plate, where the plates rub against each other.

When this happens, plate tectonics cause natural disasters around the world, including earthquakes, tsunamis, and volcanic eruptions.

But the crushing of the tectonic plates caused most of the Earth’s mountains to form – a process called “orogeny” – including the Himalayas.

The map shows the tectonic plates of the lithosphere on Earth.  Orogeny is the process by which tectonic plates converge and mountain systems are created

The map shows the tectonic plates of the lithosphere on Earth. Orogeny is the process by which tectonic plates converge and mountain systems are created

“In the case of the Andes and the Himalayas, the orogeny has led to a significant thickening of the continental crust”, explain the authors of the study.

“Recent attempts to provide geochemical approximations of crustal thickness have enabled geologists to track crustal thickness through geologic time. “

Previous knowledge that the earth’s crust was thin during the Boring Billion has led some to believe it was a period of “orogenic quiescence” or dormancy.

But the authors of this new article say that the geological record is “plentiful” with ancient orogenic belts during this period, as evidenced by metamorphic and igneous rocks.

“In particular, metamorphic rocks display higher than normal temperature / pressure ratios, indicating an unusually warm crust,” they say.

The Earth has three layers: the crust (made of solid rocks and minerals), the mantle, and the core.  Today, under large mountain ranges, such as the Alps or Sierra Nevada, the base of the earth's crust can reach 100 km deep.

The Earth has three layers: the crust (made of solid rocks and minerals), the mantle, and the core. Today, under large mountain ranges, such as the Alps or Sierra Nevada, the base of the earth’s crust can reach a depth of 100 km.

This created a style of plate tectonics much like “a waltz on a slippery dance floor”, the Guardian reports – rather than the violent dodgem-car style we see today.

Learning more about the Boring Billion – which occurred in the middle of the Proterozoic Era – could shed light on how contemporary tectonic plates have become so powerful.

During the Boring Billion, the most advanced life on Earth was algae, and oxygen levels were much lower than they are today.

But despite its boring reputation, a study in 2017 discovered that the origin of photosynthesis in plants dates back to 1.25 billion years ago during the period.

The era may have paved the way for the proliferation of more complex life forms that peaked 541 million years ago with the so-called Cambrian Explosion.

The Cambrian explosion saw an explosion of new animal phyla, likely due to a surge in oxygen, including arthropods with legs.


Research is underway to date with more precision the appearance of the different stages of life on Earth, which is more than 4.5 billion years old.

3.8 billion years ago, it is believed that the first life appeared as single cells

Multicellular life began to evolve 2.1 billion years ago.

The first animals appeared 800 to 600 million years ago, including the first arthropods and later fish.

Plants were born on earth 475 million years ago.

400 years ago insects and seeds appeared.

360 million years ago, amphibians began to evolve and 300 million years ago reptiles, followed soon after by dinosaurs.

200 million years ago, the first mammals appeared.

150 million years ago, birds began to develop.

130 million years ago, flowers were born.

60 million years ago, primates arrived on Earth.

2.5 million years ago, the genus Homo (including humans and our predecessors) arrived, leading to the evolution of anatomically modern humans 200,000 years ago.

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Declining oxygen will eventually suffocate most lives on Earth Sat, 09 Oct 2021 20:07:12 +0000

For now, life thrives on our oxygen-rich planet, but Earth hasn’t always been so – and scientists have predicted that in the future the atmosphere will once again be rich in methane and poor in methane. oxygen.

It probably won’t happen for about a billion years. But when the change does happen, it will happen fairly quickly, suggests the study earlier this year.

This change will return the planet to something like the state it was in before what is known as the Great Oxidation Event (GOE) about 2.4 billion years ago.

Additionally, the researchers behind the new study say that atmospheric oxygen is unlikely to be a permanent feature of habitable worlds in general, which has implications for our efforts to detect signs of more life. far in the Universe.

“The model predicts that deoxygenation of the atmosphere, with a sudden drop in atmospheric O2 to levels reminiscent of Archean Earth, will most likely be triggered before the onset of humid greenhouse conditions in the Earth’s climate system. and before the significant loss of surface water from the atmosphere, ”the researchers wrote in their published article.

At this point, that will be the end of the road for humans and most other life forms that depend on oxygen to get through the day, so hopefully we can find a way out of the planet at some point in the years. next billion years. .

To reach their conclusions, the researchers ran detailed models of the Earth’s biosphere, taking into account changes in the Sun’s brightness and the corresponding drop in carbon dioxide levels, as the gas breaks down due to l ‘increased heat levels. Less carbon dioxide means less photosynthetic organisms such as plants, which would result in less oxygen.

Scientists have previously predicted that an increase in solar radiation would wipe ocean waters from our planet’s surface within about 2 billion years, but the new model – based on an average of just under 400,000 simulations – said that reducing oxygen will kill off life first.

“The drop in oxygen is very, very extreme,” said Earth scientist Chris Reinhard of the Georgia Institute of Technology. New Scientist earlier this year. “We’re talking about a million times less oxygen than there is today.”

What makes the study particularly relevant today is our search for habitable planets outside the solar system.

More and more powerful telescopes are coming online and scientists want to know what to look for in the reams of data these instruments collect.

We may need to look for other biosignatures besides oxygen to have the best chance of spotting life, the researchers say. Their study is part of the NASA NExSS (Nexus for Exoplanet System Science) project, which studies the habitability of planets other than our own.

According to calculations made by Reinhard and environmental scientist Kazumi Ozaki of the University of Toho in Japan, the habitable history of the oxygen-rich Earth may only last 20-30% of the planet’s lifespan in its together – and microbial life will carry to exist long after we are gone.

“The atmosphere after the great deoxygenation is characterized by high methane, low CO2 levels and no ozone layer,” Ozaki said. “The Earth system is likely to be a world of anaerobic life forms.”

The research was published in Geosciences of nature.

A version of this article was first published in March 2021.

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