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Planets with oxygen not necessarily good candidates for ET life?


Researchers have found that the presence of oxygen in a planet’s atmosphere may not be a strong indicator of life:

Simulating in the lab the atmospheres of planets beyond the solar system, researchers successfully created both organic compounds and oxygen, absent of life.

The findings, published Dec. 11 by the journal ACS Earth and Space Chemistry, serve as a cautionary tale for researchers who suggest the presence of oxygen and organics on distant worlds is evidence of life there.

“Our experiments produced oxygen and organic molecules that could serve as the building blocks of life in the lab, proving that the presence of both doesn’t definitively indicate life,” says Chao He, assistant research scientist in the Johns Hopkins University Department of Earth and Planetary Sciences and the study’s first author. “Researchers need to more carefully consider how these molecules are produced.”

The research team found multiple scenarios that produced both oxygen and organic molecules that could build sugars and amino acids—raw materials for which life could begin—such as formaldehyde and hydrogen cyanide.

“People used to suggest that oxygen and organics being present together indicates life, but we produced them abiotically in multiple simulations,” He says. “This suggests that even the co-presence of commonly accepted biosignatures could be a false positive for life.”
Johns Hopkins University, “Alien imposters: Planets with oxygen don’t necessarily have life” at Phys.org

Paper. (paywall)

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See also: Oxygen on the early Earth: More potential plot twists than a long-running soap…

But if this find holds up, it could link up with detection of life forms very early in the planet’s history.

See also: Researchers: Earth’s oxygen rose and fell several times before the Great Oxidation Event 2.2 bya

Photosynthesis pushed back even further. Time to revisit the “Boring Billion” claim

Researchers: Extreme fluctuations in oxygen levels, not gradual rise, sparked Cambrian explosion Explanations of the dramatic Cambrian explosion of life forms (540 million years ago) are a cottage industry, with arguments about oxygen a staple of the discussion. At times, it feels like trying to understand World War II without allowing for the possibility that any intention underlay any of the events. Maybe that’s why the issues can’t be resolved.

Maverick theory: Cambrian animals remade the environment by generating oxygen

Did a low oxygen level delay complex life on Earth?

There was only a small oxygen jump

Animals didn’t “arise” from oxygenation, they created it, researchers say

Theory on how animals evolved challenged: Some need almost no oxygen

New study: Oxygenic photosynthesis goes back three billion years

Enough O2 long before animals?

Life exploded after slow O2 rise?

The Total Myth of Ocean Acidification, Part Deux: The Scientific Basis David Middleton / June 13, 2018 Conclusion (after in-depth analysis of data) The Earth isn’t behaving any differently over the past 150 years than it has behaved over the past [fill in the blank] years. Same as it ever was… https://wattsupwiththat.com/2018/06/13/the-total-myth-of-ocean-acidification-part-deux-the-scientific-basis/
https://www.oceanscientists.org/index.php/topics/ocean-deoxygenation Mung
The Place of Life and Man in Nature: Defending the Anthropocentric Thesis - Michael J. Denton - February 25, 2013 Summary (page 11) Many of the properties of the key members of Henderson’s vital ensemble —water, oxygen, CO2, HCO3 —are in several instances fit specifically for warm-blooded, air-breathing organisms such as ourselves. These include the thermal properties of water, its low viscosity, the gaseous nature of oxygen and CO2 at ambient temperatures, the inertness of oxygen at ambient temperatures, and the bicarbonate buffer, with its anomalous pKa value and the elegant means of acid-base regulation it provides for air-breathing organisms. Some of their properties are irrelevant to other classes of organisms or even maladaptive. It is very hard to believe there could be a similar suite of fitness for advanced carbon-based life forms. If carbon-based life is all there is, as seems likely, then the design of any active complex terrestrial being would have to closely resemble our own. Indeed the suite of properties of water, oxygen, and CO2 together impose such severe constraints on the design and functioning of the respiratory and cardiovascular systems that their design, even down to the details of capillary and alveolar structure can be inferred from first principles. For complex beings of high metabolic rate, the designs actualized in complex Terran forms are all that can be. There are no alternative physiological designs in the domain of carbon-based life that can achieve the high metabolic activity manifest in man and other higher organisms. http://bio-complexity.org/ojs/index.php/main/article/view/BIO-C.2013.1/BIO-C.2013.1 Privileged Species – video (2015) https://youtu.be/VoI2ms5UHWg Dr. Michael Denton Interview Excerpt Question 14: 14. Q: ,,,you also detail that nature isn’t fine-tuned for just any kind of life, but life specifically like human life. Would you expound on this for our readers? A: there are certain elements of the fine-tuning which are clearly for advanced being like ourselves. We are warm-blooded, terrestrial aerobes; we use oxidation to get energy, we’re warm-blooded and we breathe air. We get our oxygen from the air.,,, Or consider the generation and utilization of oxygen. We use oxygen, but many organisms don’t use oxygen; for a lot of organisms it’s a poison. So how do we get our oxygen? When we look at the conditions in the universe for photosynthesis, we find a magical collusion between of all sorts of different elements of fitness. First of all the atmospheric gases let through visual light which has got the right energy for biochemistry, for photosynthesis. And what are the gases in the atmosphere that let through the light? Well, carbon dioxide, water vapor, oxygen, and nitrogen. And what are the basic reactants which are involved in photosynthesis? Well, oxygen, water, and CO2. The same compounds that let through the light are also the main ‘players’ in photosynthesis. And then you might wonder what about the harmful radiations? UV, Gamma rays, microwaves? Well to begin with the sun only puts out most of its electromagnetic radian energy in the visual region (light) and near infrared (heat) and puts out very little in the dangerous regions (UV’s, gamma rays, X-rays etc.). And wonder on wonder, the atmospheric gases absorb all these harmful radiations. And so on and on and on, one anthropocentric biofriendly coincidence after another. And what provides the necessary warmth for photosynthesis, indeed for all life on earth. What keeps the average temperature of the earth above freezing? Well water vapor and carbon dioxide. If it wasn’t for water vapor and CO2 in the atmosphere the temperature of the earth would be -33 centigrade. Now when you consider all these factors necessary for the generation of oxygen via photosynthesis knowing that not all organisms use oxygen implying that all these coincidences are irrelevant to the vast majority of all species (most of the biomass on the planet may well be anaerobic unicellular life occupying the hot deep biosphere in the sub surface rocks) never use oxygen, its clear that the special fitness of nature for oxygen utilization is for us. http://successfulstudent.org/dr-michael-denton-interview/ Fine tuning of Light, to Atmosphere, Water, Photosynthesis, and Human Vision (etc.) - video https://www.youtube.com/watch?v=WiN9dU0W6rQ Paper: https://docs.google.com/document/d/1LuWUW26yc_as4QUHau4Q83-4VBjWMMAdQgGv513_YuU/edit
U-rich Archaean sea-£oor sediments from Greenland - indications of > 3700 Ma oxygenic photosynthesis - 2003 Minik T. Rosing, Robert Frei Excerpt conclusion: The high biomass productivity of planktonic organisms, the strongly 13C-depleted carbon isotopic signature and the evidence for the presence of oxidized aquatic environments all suggest that oxygenic photosynthesis had developed before 3700 Ma. http://citeseerx.ist.psu.edu/viewdoc/download?doi= When did oxygenic photosynthesis evolve? - Roger Buick - 2008 Excerpt:,, U–Pb data from ca 3.8?Ga metasediments suggest that this metabolism could have arisen by the start of the geological record. Hence, the hypothesis that oxygenic photosynthesis evolved well before the atmosphere became permanently oxygenated seems well supported. http://rstb.royalsocietypublishing.org/content/363/1504/2731.long New study: Oxygenic photosynthesis goes back three billion years - September 26, 2013 - vjtorley Excerpt: If Buick is correct here, then oxygenic photosynthesis goes right back to the very dawn of life. https://uncommondesc.wpengine.com/intelligent-design/new-study-oxygenic-photosynthesis-goes-back-three-billion-years/ Breathing new life into Earth: New research shows evidence of early oxygen on our planet – August 2011 Excerpt: Waldbauer and Summons surmise that oxygen production and consumption may have occurred in the oceans for hundreds of millions of years before the atmosphere saw even a trace of the gas. They say that in all likelihood, cyanobacteria, blue-green algae living at the ocean surface, evolved the ability to produce O2 via sunlight in a process known as oxygenic photosynthesis. But instead of building up in the oceans and then seeping into the atmosphere, O2 may have been rapidly consumed by early aerobic organisms. Large oceanic and atmospheric sinks, such as iron and sulfide spewing out of subsea volcanoes, likely consumed whatever O2 was left over. http://www.physorg.com/news/2011-08-life-earth-evidence-early-oxygen.html Iron in Primeval Seas Rusted by Bacteria – Apr. 23, 2013 Excerpt: The oldest known iron ores were deposited in the Precambrian period and are up to four billion years old. ,,, This research not only provides the first clear evidence that microorganisms were directly involved in the deposition of Earth’s oldest iron formations; it also indicates that large populations of oxygen-producing cyanobacteria were at work in the shallow areas of the ancient oceans, while deeper water still reached by the light (the photic zone) tended to be populated by anoxyenic or micro-aerophilic iron-oxidizing bacteria which formed the iron deposits.,,, http://www.sciencedaily.com/releases/2013/04/130423110750.htm
Of related note as to just how amazing this is:
"There is no question about photosynthesis being Irreducibly Complex. But it’s worse than that from an evolutionary perspective. There are 17 enzymes alone involved in the synthesis of chlorophyll. Are we to believe that all intermediates had selective value? Not when some of them form triplet states that have the same effect as free radicals like O2. In addition if chlorophyll evolved before antenna proteins, whose function is to bind chlorophyll, then chlorophyll would be toxic to cells. Yet the binding function explains the selective value of antenna proteins. Why would such proteins evolve prior to chlorophyll? and if they did not, how would cells survive chlorophyll until they did?" Uncommon Descent Blogger Evolutionary biology: Out of thin air John F. Allen & William Martin: The measure of the problem is here: “Oxygenetic photosynthesis involves about 100 proteins that are highly ordered within the photosynthetic membranes of the cell." http://www.nature.com/nature/journal/v445/n7128/full/445610a.html Of note: anoxygenic (without oxygen) photosynthesis is even more of a complex chemical pathway than oxygenic photosynthesis is: "Remarkably, the biosynthetic routes needed to make the key molecular component of anoxygenic photosynthesis are more complex than the pathways that produce the corresponding component required for the oxygenic form."; Early Life Remains Complex By Fazale R. Rana (FACTS for FAITH Issue 7, 2001)
Terraforming just became a little easier. They should start sending payloads of the chemicals to Mars- designed to mix and disperse upon landing./
Life existed on earth for a long time before aerobic life appeared.
Right. And allegedly it produced the O2, the bulk of it anyway (allegedly), that metazoans need. Anaerobic environments are good for microbes but nothing else. ET
Being a chemist, I know that the term “organic molecule” does not denote a product of life. It is used more out of tradition than out of fact. The fact that we use oxygen biases our perception of what life requires. Life existed on earth for a long time before aerobic life appeared. Ed George

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