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Researchers: Chemical evidence of life on Earth 3.2 billion years ago?

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3.2 bya sedimentary rock/R. Buick, UW

From ScienceDaily:

A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes — essential to viruses, bacteria and all other organisms — life on the early Earth would have been scarce.

The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.

“People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”

They’re just dreamin’ about the spark, of course. Life differs from non-life mostly by its high information content, and a spark won’t do that for us.

Even the oldest samples, 3.2 billion years old — three-quarters of the way back to the birth of the planet — showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.

“Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.”

Well, if it is not so difficult for them to evolve, why don’t we see life coming into existence from nothing during subsequent billions of years? Why are we confident that all life comes from life?

But, shrug, the researchers must at all costs keep the Darwin trolls quiet. Anyway, here’s the abstract from Nature:

Nitrogen is an essential nutrient for all organisms that must have been available since the origin of life. Abiotic processes including hydrothermal reduction1, photochemical reactions2, or lightning discharge3 could have converted atmospheric N2 into assimilable NH4+, HCN, or NOx species, collectively termed fixed nitrogen. But these sources may have been small on the early Earth, severely limiting the size of the primordial biosphere4. The evolution of the nitrogen-fixing enzyme nitrogenase, which reduces atmospheric N2 to organic NH4+, thus represented a major breakthrough in the radiation of life, but its timing is uncertain5, 6. Here we present nitrogen isotope ratios with a mean of 0.0 ± 1.2‰ from marine and fluvial sedimentary rocks of prehnite–pumpellyite to greenschist metamorphic grade between 3.2 and 2.75 billion years ago. These data cannot readily be explained by abiotic processes and therefore suggest biological nitrogen fixation, most probably using molybdenum-based nitrogenase as opposed to other variants that impart significant negative fractionations7. Our data place a minimum age constraint of 3.2 billion years on the origin of biological nitrogen fixation and suggest that molybdenum was bioavailable in the mid-Archaean ocean long before the Great Oxidation Event. (paywall)

See also:

Does nature just “naturally” produce life?

Can all the numbers for life’s origin just happen to fall into place?

Origin of life: Could it all have come together in one very special place?

Maybe if we throw enough models at the origin of life… some of them will stick?

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7 Replies to “Researchers: Chemical evidence of life on Earth 3.2 billion years ago?

  1. 1
    ppolish says:

    Oldest fossils are plants 3.5billion years old. Moses could not comprehend “microbial communities” – so he called them plants. Close enough.

  2. 2
  3. 3
    bornagain77 says:

    A few related notes: Roger Buick previously made a strong case for photosynthesis at 3.8 billion years ago

    When did oxygenic photosynthesis evolve? – Roger Buick – 2008
    Excerpt:,, U–Pb data from ca 3.8Ga 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.

    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. (also see comment #8 for more detailed notes on photosynthesis at 3.8 billion years ago)

    Supporting evidence

    Life’s history in iron – Nov. 7, 2014
    Excerpt: A new study examines how Earth’s oldest iron formations could have been formed before oxygenic photosynthesis played a role in oxidizing iron.,,,
    Microorganisms that photosynthesize in the absence of oxygen assimilate carbon by using iron oxide (Fe(II)) as an electron donor instead of water. While oxygenic photosynthesis produces oxygen in the atmosphere (in the form of dioxygen), anoxygenic photosynthesis adds an electron to Fe(II) to produce Fe(III).
    “In other words, they oxidize the iron,” explains Pecoits. “This finding is very important because it implies that this metabolism was already active back in the early Archean (ca. 3.8 Byr-ago).”

    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 (the Earth itself is estimated to be about 4.6 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.,,,

    The Sudden Appearance Of Life On Earth (3.9 billion years ago) – video

    When Did Life on Earth Begin? Ask a Rock (3.85 bya)

  4. 4
    bornagain77 says:

    Fine tuning of nitrogen cycle

    Engineering and Science Magazine – Caltech – March 2010
    Excerpt: “Without these microbes, the planet would run out of biologically available nitrogen in less than a month,” Realizations like this are stimulating a flourishing field of “geobiology” – the study of relationships between life and the earth. One member of the Caltech team commented, “If all bacteria and archaea just stopped functioning, life on Earth would come to an abrupt halt.” Microbes are key players in earth’s nutrient cycles. Dr. Orphan added, “…every fifth breath you take, thank a microbe.”

    Planet’s Nitrogen Cycle Overturned – Oct. 2009
    Excerpt: “Ammonia is a waste product that can be toxic to animals.,,, archaea can scavenge nitrogen-containing ammonia in the most barren environments of the deep sea, solving a long-running mystery of how the microorganisms can survive in that environment. Archaea therefore not only play a role, but are central to the planetary nitrogen cycles on which all life depends.,,,the organism can survive on a mere whiff of ammonia – 10 nanomolar concentration, equivalent to a teaspoon of ammonia salt in 10 million gallons of water.”

    Global Nitrogen Availability Consistent for Past 500 Years Linked to Carbon Levels – Mar. 21, 2013
    Excerpt: “Our best idea is that the nitrogen and carbon cycles were linked tightly back then and they are linked tightly today,” McLauchlan said. “Humans are now manipulating both nitrogen and carbon at the same time, which means that there is no net effect on the biosphere.”,,,

    as well:

    Long term terraforming of the earth for the habitability of higher lifeforms,,, for humans in particular

  5. 5
    Jim Smith says:

    It makes the Cambrian explosion even more inexplicable.

  6. 6
    Piotr says:

    As usual, a misleading title. There is chemical evidence of life much older than 3.2 Gy. The problem discussed in the article is is not how life originated (and what, if anything, sparks had to do with it), but how long ago microorganisms began to fix atmospheric N2 directly with the help of nitrogenases. But I have to admit you are making progress. At least you cite the Nature abstract in addition to ScienceDaily snippets!

  7. 7
    Joe says:


    There is chemical evidence of life much older than 3.2 Gy.

    Both the time and the evidence are suspect. The time is suspect because it relies on a an undemonstrated method of planet building. That in turn requires the planet to be so hot that no crystals from the material remained. That also cannot be tested. And the evidence for living organisms around before 3.2 bya may not be evidence for living organisms- it is debateable.

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