¿Comenzó la vida en los suelos hídricos de Tierra hace 4,500 Millones de Años? (¿y el cambio climático?)

 0-extraterrestre-origen-de-la-vida

¿O fueron los extraterrestres con su portentosa ingeniería planetaria de Terrasformación. Fuente: Colaje de imágenes google

En el post que redactamos hace más de ocho años y que llevaba como título: Sobre los Posibles Orígenes de la Vida (Entre Jaimito y Mafalda) escribíamos en clave de humor: ¡Veamos Pancho! ¿Dónde está Dios?, a lo cual el gafotas responde: “En el cielo, en la Tierra y en todas las partes”. Muy bien, como siempre el primero. Veamos ahora Jaimito, ¿Dónde se originó la Vida?. Y para su sorpresa,  este trasto de criatura espeta ¿depende de la fuente de información científica que utilice?. ¡¡¡¡¡Jaimito!!!!!!, no te repito la pregunta, o me respondes o te quedas castigado después de clase. ¡Pues en el cielo en La Tierra y en todas las partes!. Mientras Doña Eucrasia castiga a Jaimito, Mafalda piensa para sí misma: ¡¡¡Qué vida tan divina!!!!. Empero Jaimito llevaba la razón, al menos si uno atiende a la documentación aparecida en los noticieros científicos.

Desde entonces han aparecido decenas, por no decir centenares de artículos, pero el asunto estriba en que seguimos mareando la perdiz. ¿Cómo es posible que se propongan una y mil veces lo mismo, es decir nada, ni muy seguro, ni tan siquiera altamente probable? Cuando se tratan temas candentes, actualmente siempre ocurre lo mismo: nuevas técnicas instrumentales, ciertas evidencias que debieran ser corroboradas, y últimamente, sin cesar, los escenarios generados por los modelos de simulación dan lugar a un abanico al parecer casi infinito de posibilidades. Los modelos de simulación numérica, no dejan de ser más que modelos basados en las evidencias aludidas y asunciones teóricas siempre cuestionables. Con el tiempo, prácticamente todos estos estudios pasarán al baúl de los recuerdos. Esto no es ciencia, sino especulación tras especulación, y vuelta a empezar. No se puede confundir al ciudadano de forma tan indecente.

Hoy os presentamos varias noticias que no se ponen de acuerdo ni en cómo llegaron a la Tierra los diferentes elementos esenciales de la tabla periódica, ni cómo/cuando se formó. Y si esto ocurre, ¿cómo se puede insistir una y otra vez en dar cuenta de lo que pasó poco después? Lo más tragicómico del tema es que ya, hace varias décadas, se propusieron los mismos escenarios, que los que ahora salen a la palestra.  Hoy os vamos a mostrar varias noticias (con algún párrafo traducido), aunque nos centraremos en la primera redactada en español castellano: Un estudio afirma que meteoritos y lagunas de agua fueron el origen de la vida, que no las surgencias termales de los fondos oceánicos. Empero tal conjetura tiene más de ¡50 años! de antigüedad! Lo mismo ocurre con las primeras moléculas autoreplicantes, aunque soslayaremos hoy este tema. Es decir la última vuelta atrás es volver a incluir los protosuelos hídricos en la primera línea. De este tipo de edafotaxa ya os hemos hablado en más de una ocasión. ¿Y se trata en esencia de la última novedad?, pero…¡un momento!…… en el texto aludido puede leerse “señalaron que la vida empezó mientras la Tierra todavía estaba formándose, con continentes emergiendo de los océanos y meteoritos impactando en la superficie”. ¡Vale, ¿pero ya había charcas?. Al parecer sí, ya que seguidamente se nos ¿informa? de que….: ¡los meteoritos transportaron elementos esenciales para la vida, mientras que los ciclos secos y húmedos ayudaron a ensamblar los bloques básicos de la estructura molecular en moléculas de ARN. ¿Alternancia de ciclos secos y húmedos?. Si se piensa detenidamente en esta sentencia, resulta que ofrece pistas muy interesantes que los autores “indebidamente han soslayado”. Entendida literalmente, nos habla de periodos de sequía y periodos de humedad. Mutalis mutandis, la nota de prensa habría podido titularse a bombo y platillo: ¡La vida fue el resultado de un cambio  climático!. ¡Otra vez!. Tengo ¡ya pesadillas!: todos nuestros males son culpa del cambio climático: ¿aunque este fuera natural?. No necesariamente, bien pudo crearse por una civilización extraterrestre y su portentosa ingeniería planetaria. ¿Acaso no pretendemos hacer lo mismo en otros planetas con nuestra gloriosa geoingeniería planetaria?, es decir ¿la denominada Terraformación?. Pues bien, ya tengo mi propuesta, ¡una más! made in “Un universo invisible bajo nuestros pies!.

Os dejo primero la noticia en castellano que propone los suelos/protosuelos como candidato más verosímil. ¡Da igual!. En estos temas sucede como en muchas  elecciones políticas: al final ninguna partido/propuesta alcanza el número de votos suficientes como para tener una cómoda legislatura, necesitando hacer pactos con otros  partidos/propuestas. Pues eso consenso, necesitamos consenso. ¿Consenso de qué?. ¡Ya me he perdido!.

Juan José Ibáñez

Continua…..

Un estudio afirma que meteoritos y lagunas de agua fueron el origen de la vida

La vida se inicio en la Tierra hace entre 4.500 y 3.700 millones de años gracias al impacto de meteoritos en pequeñas lagunas de la superficie terrestre, según un estudio canadiense que se acaba de publicar.

El texto explica que los meteoritos transportaron elementos esenciales para la vida, mientras que los ciclos secos y húmedos ayudaron a fusionar los bloques básicos de la estructura molecular en moléculas de ARN (ácido ribonucleico) capaces de autorreproducirse. Estas moléculas de ARN constituyeron el primer código genético de la vida en la Tierra.

El estudio, publicado en la revista científica Proceedings of the National Academy of Science, ha sido realizado por investigadores de la Universidad McMaster de Canadá y el Instituto Max Planck de Alemania. Sus principales autores, Ben K.D. Pearce y Ralph Pudritz del Origins Institute de la Universidad McMaster, señalaron que la vida empezó mientras la Tierra todavía estaba formándose, con continentes emergiendo de los océanos y meteoritos impactando en la superficie. Para llegar a estas conclusiones, los investigadores realizaron una serie de cálculos de astrofísica, geología, química y biología, entre otras disciplinas.

Los autores indicaron que la creación de polímeros de ARN, el componente esencial de moléculas orgánicas conocidas como nucleótidos, transportados por los meteoritos, alcanzaron una concentración crítica en lagunas de agua. Los polímeros eran imperfectos “capaces de mejorar gracias a la evolución darwiniana“, precisaron los investigadores en un comunicado. Pearce afirmó que “ese es el Santo Grial de los orígenes de vida química experimental“.

La creación del ARN dio lugar con el tiempo al desarrollo de ADN (ácido desoxirribonucleico). Pudritz manifestó que “el ADN es demasiado complejo para haber sido el primer aspecto de la vida que apareció. Tuvo que iniciarse con algo distinto, que fue el ARN”. Sus cálculos señalan que las lagunas de agua templada que existieron en la Tierra, y no chimeneas hidrotermales en el fondo de los océanos que defiende otra teoría sobre el origen de la vida, son el lugar más probable donde se desarrolló el ARN inicial.

Además, el polvo espacial tampoco sería la fuente de los nucleótidos, los ladrillos del material genético. Aunque este contenía los materiales necesarios no pudo llegar a la Tierra con la suficiente velocidad. Para los autores es más probable que los meteoritos, que eran mucho más comunes en aquellas etapas del Sistema Solar, fueran los vehículos más probables para los ingredientes de la vida.

The volatile processes that shaped the Earth
by Staff Writers
Oxford UK (SPX) Oct 02, 2017

Oxford University scientists have shed new light on how the Earth was first formed. Based on observations of newly-forming stars, scientists know that the solar system began as a disc of dust and gas surrounding the centrally-growing sun. The gas condensed to solids which accumulated into larger rocky bodies like asteroids and mini-planets. Over a period of 100 million years these mini-planets collided with one another and gradually accumulated into the planets we see today, including the Earth.

Los científicos de la Universidad de Oxford han arrojado nueva luz sobre cómo se formó la Tierra por primera vez. Basados en observaciones de estrellas recién formadas, los científicos saben que el sistema solar comenzó como un disco de polvo y gas que rodea al sol de crecimiento central. El gas se condensaba en sólidos que se acumulaban en cuerpos rocosos más grandes como asteroides y mini-planetas. Durante un período de 100 millones de años estos mini-planetas chocaron entre sí y gradualmente se acumuló en los planetas que vemos hoy, incluyendo la Tierra

Although it is widely understood that Earth was formed gradually, from much smaller bodies, many of the processes involved in shaping our growing planet are less clear. In a new study featured on the cover of the latest edition of Nature, researchers from the University of Oxford’s Department of Earth Sciences untangle some of these processes, revealing that the mini-planets added to Earth had previously undergone melting and evaporation. They also address another scientific conundrum: the Earth’s depletion in many economically important chemical elements.

It is well known that the Earth is strongly depleted, relative to the solar system as a whole, in those elements which condensed from the early gas disc at temperatures less than 1000 C (for example, lead, zinc, copper, silver, bismuth, and tin).

The conventional explanation is that the Earth grew without these volatile elements and small amounts of an asteroidal-type body were added later. This idea cannot, however, explain the “over abundance” of several other elements – notably, indium, which is now used in semiconductor technologies, as well as TV and computer screens.

Postgraduate student Ashley Norris and Bernard Wood, Professor of Mineralogy at Oxford’s Department of Earth Sciences, set out to uncover the reasons behind the pattern of depletion of these volatile elements on Earth and for the “overabundance” of indium. They constructed a furnace in which they controlled the temperature and atmosphere to simulate the low oxidation state of the very early Earth and planetesimals. In a particular series of experiments they melted rocks at 1300 C in oxygen-poor conditions and determined how the different volatile elements were evaporated from the molten lava.

During the experiments each of the elements of interest evaporated by different amounts. The lava samples were then rapidly cooled and the patterns of element loss determined by chemical analysis. The analyses revealed that the relative losses (volatilities) measured in the molten lava experiments agree very closely with the pattern of depletion observed in the Earth. In particular, indium volatility agrees exactly with its observed abundance in the Earth – its abundance, turns out not to be an anomaly.

Professor Bernard Wood said: ‘Our experiments indicate that the pattern of volatile element depletion in the Earth was established by reaction between molten rock and an oxygen-poor atmosphere. These reactions may have occurred on the early-formed planetesimals which were accreted to Earth or possibly during the giant impact which formed the moon and which is believed to have caused large-scale melting of our planet.’

Nuestros experimentos indican que el patrón de agotamiento de elementos volátiles en la Tierra se estableció por reacción entre la roca fundida y una atmósfera pobre en oxígeno. Estas reacciones pueden haber ocurrido en los primeros planetesimales formados que se acrecentaron a la Tierra o posiblemente durante el impacto gigante que formó la Luna y que se cree que causó el derretimiento a gran escala de nuestro planeta.

Having focused their original experiments on 13 key elements, the team are in the process of looking at how other elements, such as chlorine and iodine, behave under the same conditions. Ashley Norris said: ‘Our work shows that interpretation of volatile depletion patterns in the terrestrial planets needs to focus on experimental measurement of element volatillities.’

 Study: 3.95 billion-year-old rocks contain earliest traces of life

Estudio: 3,95 mil millones de años de edad, las rocas contienen las primeras huellas de la vida

Washington (UPI) Sep 27, 2017
A team of Japanese researchers believe they’ve discovered the oldest known evidence of life on Earth. The scientists found signs of biological activity in 3.95 billion-year-old rocks from Labrador in northeast Canada. The rock samples were formed when Earth was 500 million years old. During the Eoarchaean Era – the first during which Earth featured a curst – the planet was covered wit … read more

Life may have gained a foothold on Earth more than 4bn years ago, according to researchers who believe that fragments of carbon found in rocks in Canada are remnants of ancient organisms.Researchers in Japan analysed graphite particles in rocks from the Saglek region of northern Labrador and found that they contained potential traces of life. In work last year, the team dated the band of rocks to 3.95bn years old. Carbon found in 3.95bn-year-old rocks is remnant of ancient life – researchers. Graphite particles suggest that the first organisms emerged on Earth more than 4bn years ago during one of the most violent periods in our planet’s history

 Life may have gained a foothold on Earth more than 4bn years ago, according to researchers who believe that fragments of carbon found in rocks in Canada are remnants of ancient organisms. Researchers in Japan analysed graphite particles in rocks from the Saglek region of northern Labrador and found that they contained potential traces of life. In work last year, the team dated the band of rocks to 3.95bn years old. Oldest fossils on Earth discovered in 3.7bn-year-old Greenland rocks. The claim that these rocks contain remnants of life now faces intense scrutiny from other scientists, but if the research published in Nature stands up, it suggests that the first organisms to emerge on Earth did so during one of the most violent periods in the planet’s history. Until 3.8bn years ago, the Earth was pounded by asteroids and comets left over from the formation of the solar system.

La vida pudo haber ganado un pie en la tierra hace más de 4bn años, según los investigadores que creen que los fragmentos del carbón encontrados en rocas en Canadá son restos de organismos antiguos.

Investigadores en Japón analizaron partículas de grafito en rocas de la región de Saglek, en el norte de Labrador, y encontraron que contenían potenciales rastros de vida. En el trabajo el año pasado, el equipo fechó la banda de rocas a 3.95 millones de años.Fósiles más antiguos de la Tierra descubiertos en 3,7 mil millones de años de rocas de Groenlandia

La afirmación de que estas rocas contienen restos de la vida ahora se enfrenta a un escrutinio intenso de otros científicos, pero si la investigación publicada en la naturaleza se levanta, sugiere que los primeros organismos a surgir en la Tierra lo hizo durante uno de los períodos más violentos de la historia del planeta . Hasta hace 3.8bn años, la tierra fue golpeada por los asteroides y los cometas sobrantes de la formación del sistema solar.

Oldest fossils on Earth discovered in 3.7bn-year-old Greenland rocks

The claim that these rocks contain remnants of life now faces intense scrutiny from other scientists, but if the research published in Nature stands up, it suggests that the first organisms to emerge on Earth did so during one of the most violent periods in the planet’s history. Until 3.8bn years ago, the Earth was pounded by asteroids and comets left over from the formation of the solar system.

Meteors splashing into warm ponds sparked life on Earth
by Staff Writers
Miami (AFP) Oct 2, 2017

 UTA study sheds new light on evolution

by Staff Writers
Arlington TX (SPX) Oct 05, 2017

Research from the University of  Texas at Arlington and the Wadia Institute of Himalayan Geology suggests that hydrogen, oxygen, water and carbon dioxide are being generated in the earth’s mantle hundreds of kilometers below the earth’s surface.

This discovery is important as it shows how earth’s planetary evolution may have happened,” said Asish Basu, UTA professor of earth and environmental sciences and co-author of the cover paper published in Geology in August.

The researchers focused their attention on a seven-kilometer thick portion of the earth’s upper mantle now found in the High Himalayas, at altitudes between 12,000 and 16,000 feet. This section of the mantle was pushed upwards to the top of the mountains as a result of the Indian Plate pushing north into Asia, displacing the ancient Tethys ocean floor and underlying mantle to create the Himalayan Mountain Belt around 55 million years ago.

This is important as it means that we can analyze the nature of the mantle under the earth’s crust, at depths where drilling cannot reach,” Basu explained. “One key initial discovery was finding microdiamonds whose host rocks originated in the mantle transition zone, at depths between 410 and 660 kilometers below the earth’s surface.”

By studying the host rocks and associated minerals, the scientists had a unique opportunity to probe the nature of the deep mantle. They found primary hydrocarbon and hydrogen fluid inclusions along with microdiamonds by using Laser Ramon Spectroscopic study. The discovery also showed that the environment in the deep mantle transition zone depths where the diamond is formed is devoid of oxygen.

The researchers suggest that during the advective transport or mantle up-welling into shallower mantle zones, the hydrocarbon fluids become oxidized and precipitate diamond, a mechanism that may also be responsible for forming larger diamonds like the world’s most valuable, Koh-i-Noor or Mountain of Light diamond, now in the Queen of England’s crown.

We also found that the deep mantle upwelling can oxidize oxygen-impoverished fluids to produce water and carbon dioxide that are well-known to produce deep mantle melting,” said Souvik Das, UTA post-doctoral research scholar.

“This means that many of the key compounds affecting evolution like carbon dioxide and water are generated within the mantle,” he added.

Research Report: “In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone”

How did life on Earth begin? A study out Monday backs the theory that meteorites splashing into warm ponds leached essential elements that gave rise to the building blocks of life billions of years ago. The report is based on “exhaustive research and calculations” in astrophysics, geology, chemistry and biology, according a summary provided by McMaster University.

“Because there are so many inputs from so many different fields, it’s kind of amazing that it all hangs together,” said co-author Ralph Pudritz of the McMaster’s Origins Institute and its Department of Physics and Astronomy. “Each step led very naturally to the next. To have them all lead to a clear picture in the end is saying there’s something right about this.”

The life-giving potential of these so-called “warm little ponds” was raised by the famed biologist Charles Darwin, who developed the theory of evolution, in a letter to a friend in 1871.”But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts, light, heat, electricity et cetera present, that a protein compound was chemically formed, ready to undergo still more complex changes,” he wrote at the time. Since then, researchers have debated whether life emerged in ponds, or in hydrothermal vents along the ocean floor.

The latest study finds ponds were far more likely, because a cycle from wet to dry was needed to bond basic molecular building blocks in the ponds into self-replicating ribonucleic acid (RNA) molecules. These RNA molecules constituted the first genetic code for life on the planet, and came before DNA, said the findings.

“In order to understand the origin of life, we need to understand Earth as it was billions of years ago,” said co-author Thomas Henning from the Max Planck Institute for Astronomy.

“As our study shows, astronomy provide a vital part of the answer. The details of how our solar system formed have direct consequences for the origin of life on Earth.” Between 3.7 and 4.5 billion years ago, the Earth was being bombarded by meteors, at a rate about eight to 11 times higher than it does today.

The atmosphere back then was “dominated by volcanic gases, and dry land was scarce as continents were rising out of the global ocean,” said the PNAS report.

Eventually, the ingredients needed to form RNA polymers reached sufficient concentrations in pond water, and bonded together as water levels fell and rose through cycles of precipitation, evaporation and drainage. These early RNA life forms evolved, and gave rise to the development of DNA, the genetic blueprint of higher forms of life. “DNA is too complex to have been the first aspect of life to emerge,” said Pudritz. “It had to start with something else, and that is RNA.”

The full study appears in the Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed US journal.

Could interstellar ice provide the answer to birth of DNA?

York UK (SPX) Sep 15, 2017
Researchers at the University of York have shown that molecules brought to earth in meteorite strikes could potentially be converted into the building blocks of DNA. They found that organic compounds, called amino nitriles, the molecular precursors to amino acids, were able to use molecules present in interstellar ice to trigger the formation of the backbone molecule, 2-deoxy-D-ribose, of … read more

Evidence suggests life on Earth started after meteorites splashed into warm little ponds

by Staff Writers; Hamilton, Canada (SPX) Oct 05, 2017

Life on Earth began somewhere between 3.7 and 4.5 billion years ago, after meteorites splashed down and leached essential elements into warm little ponds, say scientists at McMaster University and the Max Planck Institute in Germany. Their calculations suggest that wet and dry cycles bonded basic molecular building blocks in the ponds’ nutrient-rich broth into self-replicating RNA molecules that constituted the first genetic code for life on the planet.

The researchers base their conclusion on exhaustive research and calculations drawing in aspects of astrophysics, geology, chemistry, biology and other disciplines. Though the “warm little ponds” concept has been around since Darwin, the researchers have now proven its plausibility through numerous evidence-based calculations.

Lead authors Ben K.D. Pearce and Ralph Pudritz, both of the McMaster’s Origins Institute and its Department of Physics and Astronomy, say available evidence suggests that life began when the Earth was still taking shape, with continents emerging from the oceans, meteorites pelting the planet – including those bearing the building blocks of life – and no protective ozone to filter the Sun’s ultraviolet rays.

“No one’s actually run the calculation before,” says Pearce. “This is a pretty big beginning. It’s pretty exciting.”

“Because there are so many inputs from so many different fields, it’s kind of amazing that it all hangs together,” Pudritz says. “Each step led very naturally to the next. To have them all lead to a clear picture in the end is saying there’s something right about this.”

Their work, with collaborators Dmitry Semenov and Thomas Henning of the Max Planck Institute for Astronomy, has been published in the Proceedings of the National Academy of Science.

“In order to understand the origin of life, we need to understand Earth as it was billions of years ago. As our study shows, astronomy provide a vital part of the answer. The details of how our solar system formed have direct consequences for the origin of life on Earth,” says Thomas Henning, from the Max Planck Institute for Astronomy and another co-author.

The spark of life, the authors say, was the creation of RNA polymers: the essential components of nucleotides, delivered by meteorites, reaching sufficient concentrations in pond water and bonding together as water levels fell and rose through cycles of precipitation, evaporation and drainage. The combination of wet and dry conditions was necessary for bonding, the paper says.

In some cases, the researchers believe, favorable conditions saw some of those chains fold over and spontaneously replicate themselves by drawing other nucleotides from their environment, fulfilling one condition for the definition of life. Those polymers were imperfect, capable of improving through Darwinian evolution, fulfilling the other condition.

“That’s the Holy Grail of experimental origins-of-life chemistry,” says Pearce.

That rudimentary form of life would give rise to the eventual development of DNA, the genetic blueprint of higher forms of life, which would evolve much later. The world would have been inhabited only by RNA-based life until DNA evolved.

“DNA is too complex to have been the first aspect of life to emerge,” Pudritz says. “It had to start with something else, and that is RNA.”

The researchers’ calculations show that the necessary conditions were present in thousands of ponds, and that the key combinations for the formation of life were far more likely to have come together in such ponds than in hydrothermal vents, where the leading rival theory holds that life began in roiling fissures in ocean floors, where the elements of life came together in blasts of heated water. The authors of the new paper say such conditions were unlikely to generate life, since the bonding required to form RNA needs both wet and dry cycles.

The calculations also appear to eliminate space dust as the source of life-generating nucleotides. Though such dust did indeed carry the right materials, it did not deposit them in sufficient concentration to generate life, the researchers have determined.

At the time, early in the life of the solar system, meteorites were far more common, and could have landed in thousands of ponds, carrying the building blocks of life. Pearce and Pudritz plan to put the theory to the test next year, when McMaster opens its Origins of Life laboratory that will re-create the pre-life conditions in a sealed environment.

“We’re thrilled that we can put together a theoretical paper that combines all these threads, makes clear predictions and offers clear ideas that we can take to the laboratory,” Pudritz says.

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