Ancient rocks show life could have flourished on Earth 3.2 billion years ago

February 16, 2015
The oldest rock samples, from 3.2 billion years ago, were collected in the desert in northwestern Australia. Credit: R. Buick / Univ. of Washington

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 to support more widespread 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 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."

The results were published Feb. 16 in Nature.

The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.

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."

Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.

"This is hard evidence that pushes it back a further billion years," Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of -fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth - before the atmosphere contained oxygen to weather rocks - is more mysterious.

The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of that reacted with the to release molybdenum to the water.

"We'll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited," Buick said. "Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago."

Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.

Explore further: Large bacterial population colonized land 2.75 billion years ago

More information: Isotopic evidence for biological nitrogen fixation by molybdenum-nitrogenase from 3.2 Gyr, Nature, DOI: 10.1038/nature14180

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18 comments

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Shootist
3.8 / 5 (9) Feb 16, 2015
It becomes more and more clear; life has been here since the first great magma ocean crystallized. It might have even been wiped out and re-ignited/re-established/re-seeded.

Perhaps Ceres dwarf planet holds a clue? Perhaps Vesta, where we see evidence of water action on the surface . . . https://planetary...ess.com/
Wake
5 / 5 (6) Feb 16, 2015
Why did it require something special to generate life on Earth? Just having the right conditions - water, carbon and the correct temperatures to engender chemical reactions weren't enough?
Shootist
1 / 5 (2) Feb 16, 2015
Why did it require something special to generate life on Earth? Just having the right conditions - water, carbon and the correct temperatures to engender chemical reactions weren't enough?
\

Where do you see a requirement for "special"?
verkle
Feb 16, 2015
This comment has been removed by a moderator.
Vietvet
4.2 / 5 (11) Feb 16, 2015
@verkle

Everything thats comes out of your mouth is garbage.
jsdarkdestruction
4 / 5 (8) Feb 17, 2015
Verkle, what about all the scientists who are Christian or another religion that support the theory of evolution? What about those that are agnostic?
altizar
1.7 / 5 (6) Feb 17, 2015
3.2 billion years of evolution and Obama's the best we got? Looks like we need another 3.2 Billion . . .
Mike_Massen
4.1 / 5 (9) Feb 17, 2015
verkle claimed
Obviously lightning did not create the first life here
Wrong !
It is well known electric fields & discharge products hasten many types of chemical reactions as well as adding heat. One example of nature producing a DNA base pair is formamide which leads to Guanine.

Other DNA base pairs can thus arise from subsidiary discharges altering structures of Guanine to produce intermediate reaction species to easily produce Cytosine, Thymine, Adenine etc

If you have an open non-dogmatic blind religiously twisted mind U will see these are all "amino" acids, EACH has an NH2, which is consistent with early Earth's ammonia rich atmosphere...

verkle claimed
Lightning kills life, does not create it
At the highest central curren thread sure but around it No, it does the opposite and especially so when it discharges through sea, ground, through mineral complexes etc...

cont
Mike_Massen
4.5 / 5 (8) Feb 17, 2015
verkle continues unscientific claims with NIL evidence
Evolution is the greatest lie that so-called scientists have ever thought up
Prove it.
Explain why thousands of micro-biologists use it routinely all over the world ?

verkle claims
It is not science
Prove it.
Genetics is based on sound mathematics. Evolution observed & induced is also based on probability, how is that not Science ?

How much probability/biology did U ever study ?

verkle claims
It is garbage
To a feeble & uneducated intellect, sure.

verkle claims
It cannot be replicated
Biologists can at short time scales too.

verkle claims
has never been observed
It has & over longer periods re so called higher life forms, U not included.

verkle claims
and solely lies in the imagination of atheist scientists
U have been shown the above before yet continue the same inane prattle.

verkle, like prophets of all religions ONLY make claims.

Catholic church accepts evolution :-)
Steve 200mph Cruiz
4.4 / 5 (8) Feb 17, 2015
Verkle, did you know Charles Darwin originally went to school to become a priest and remained religious his whole life?
The idea you can't be religious and a scientist is a farce.

The only reason you have a problem is because you try and use it as a science book instead of using it to give meaning to the natural world.

That's why you don't get anything out of science or religion. God doesn't make you happy or understanding because you deny God's creation. You spend all your time with your hands over your eyes and ear. You are like Helen Keller, and that's why you're actually mad at scientists.
Vietvet
3.7 / 5 (9) Feb 17, 2015
@Steve 200

Darwin quietly became an agnostic while still respecting the religious beliefs of others.
Torbjorn_Larsson_OM
5 / 5 (6) Feb 17, 2015
Since there are stromatolites from 3.5 Gyrs ago, and cyanobacteria makes them today and fix nitrogen as well, that is reasonable. But it would push today's molecular clock datings of the lineage from 3 Gyrs ago to 3.5+ Gyrs.

"Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth - before the atmosphere contained oxygen to weather rocks - is more mysterious."

Mo, or possibly W, is the central metabolic engine in Russell et al submarine alkaline hydrothermal emergence. (The forgotten pathway in the list of "a lightning bolt, interstellar dust, or a subsea volcano".) It is an early catalyst, in any case.
Osiris1
2 / 5 (4) Feb 17, 2015
Life was here on this world, we are going to find, within a hundred million years after it was formed. That is to say as soon as it had a non molton crust with a temperature of less than six hundred degrees. We find extremophiles near undersea volcanic vents living in water at extreme pressures over 600 degrees F. We also find life inside of rocks at great depths. Life is, we are also going to find, ubiquitous throughout the universe; and probably came here in the very planetesimals that formed our early Earth. The real question is: given our origin abt4.6BYA and first crust 4.5BYA; and from there a half billion years before giant impact, what life and evolution occurred THEN. The life what was wiped out in the collision. All our evolution took place in .3BY. There was time for intelligent life to evolve THEN too! Oxygen or not! What happened to Earth's forgotten children?. Be nice to think they escaped what they had to know was coming.
Torbjorn_Larsson_OM
5 / 5 (4) Feb 17, 2015
FWIW, astrobiology transitioned from making (an embarrassment of richness of) pathways to testing them about 20 years ago. The trolls do not know what they speak of re testing (and in other news dog bites man).

@Wake: In some early suggested pathways, being in the habitable zone is pretty much enough. Soup theories: "a lightning bolt", "interstellar dust", et cetera, where non-equilibrium thermodynamics makes a pool ("soup") of organics that early life consumes while it evolves metabolism.

But those are today put in tension, because a) thermodynamics of replicators have been shown to require non-equilibrium thermodynamics as well [Russell, Pross, Pascal, England,...] and b) we can now track homologies back to our ancestral geophysical systems. It turns out that because we share so many traits with submarine alkaline hydrothermal systems, those so called "dirty" RNA worlds are ~ 2*10^13 times more likely to be our ancestors than "pure" RNA worlds of "soup".

[tbctd]
Torbjorn_Larsson_OM
5 / 5 (2) Feb 17, 2015
[ctd] The window of opportunity for life is, due to replicator thermodynamics, when the planet transitions from too hot for liquid water into habitable climate. In the first instance the whole planet can reduce the primordial carbon dioxide atmosphere (produced by volcanism) to hydrocarbons, primarily methane. In the new phase it is only locally around vents that metabolism evolves, where metabolic engines can do that catalysis, else the energy barrier demands visible light and/or hundreds of degrees heat. ["The Drive for Life on Wet and Cold Worlds", Russell et al, Astrobiology 2014]

We know from the oldest Jack Hill zircon oxygen isotope data that Earth was cold and wet ~4.4 billion years ago. We also know from that zircon data set that the late bombardment was survivable. So that we can date the first lineage split (bacteria/archaea) to 4 billion years by molecular dating, and the first cyanobacteria to perhaps 3,5 billion years as here, is consistent with such early life.
Torbjorn_Larsson_OM
5 / 5 (2) Feb 17, 2015
Errata: "But those are today put in tension." - But those are today put in tension by observation,.
Mike_Massen
4.2 / 5 (5) Feb 17, 2015
Ren82 with evident bias asked with satire
. most important fundamental question whose answer puts boundary between the lies and the truth is, what is the main condition that can allow evolution process with provided appropriate physical and chemical conditions?
There are Obviously several, short list:-

a.Are all the source reactants/constituents found in life present at all times ?
b.Are all those stated in a. readily available always ?
c.Is there sufficient energy for reactants to reach activation energy ?
d.Are there varieties of environments where reactive intermediate species are stable ?
e.Is there ample environmental permutations in conjunction with a,b,c & d ?
f. Is there ample time for compounds to form ?
e.Do early "non-life" compounds have verifiable chemical paths to life's building blocks eg DNA

Obviously Ren82, the answer yes applies to all of the above AND then some U haven't considered such as metalloid crystalline protein patterning ;-)

etc etc
greenonions
5 / 5 (1) Feb 17, 2015
altizar
3.2 billion years of evolution and Obama's the best we got? Looks like we need another 3.2 Billion . . .


Surely this is powerful evidence of the process of evolution. In one generation - we go from dopey the clown - to Magna Cum Laude from Harvard law school.....

http://www.answer...ama's_IQ

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