Low level of oxygen in Earth's middle ages delayed evolution for two billion years

February 2, 2017, University of Exeter
A composite image of the Western hemisphere of the Earth. Credit: NASA

A low level of atmospheric oxygen in Earth's middle ages held back evolution for 2 billion years, raising fresh questions about the origins of life on this planet.

New research by the University of Exeter explains how oxygen was trapped at such low levels.

Professor Tim Lenton and Dr Stuart Daines of the University of Exeter Geography department, created a computer model to explain how oxygen stabilised at low levels and failed to rise any further, despite oxygen already being produced by early photosynthesis. Their research helps explain why the '', which introduced oxygen into the atmosphere around 2.4 billion years ago, did not generate modern levels of oxygen.

In their paper, published in Nature Communications, Atmospheric oxygen regulation at low Proterozoic levels by incomplete oxidative weathering of sedimentary organic carbon, the University of Exeter scientists explain how organic material - the dead bodies of simple lifeforms - accumulated in the earth's sedimentary rocks. After the Great Oxidation, and once plate tectonics pushed these sediments to the surface, they reacted with oxygen in the atmosphere for the first time.

The more oxygen in the atmosphere, the faster it reacted with this , creating a regulatory mechanism whereby the oxygen was consumed by the sediments at the same rate at which it was produced.

This mechanism broke down with the rise of land plants and a resultant doubling of global photosynthesis. The increasing concentration of oxygen in the atmosphere eventually overwhelmed the control on oxygen and meant it could finally rise to the levels we are used to today.

This helped animals colonise the land, leading eventually to the evolution of mankind.

The model suggests atmospheric oxygen was likely at around 10% of present day levels during the two billion years following the Great Oxidation Event, and no lower than 1% of the we know today.

Professor Lenton said: "This time in Earth's history was a bit of a catch-22 situation. It wasn't possible to evolve complex life forms because there was not enough oxygen in the atmosphere, and there wasn't enough oxygen because complex plants hadn't evolved - It was only when land plants came about did we see a more significant rise in .

"The history of life on Earth is closely intertwined with the physical and chemical mechanisms of our planet. It is clear that life has had a profound role in creating the world we are used to, and the planet has similarly affected the trajectory of life. I think it's important people acknowledge the miracle of their own existence and recognise what an amazing planet this is."

Life on earth is believed to have begun with the first bacteria evolving 3.8 billion years ago. Around 2.7 billion years ago the first -producing photosynthesis evolved in the oceans. But it was not until 600 million years ago that the first multi-celled animals such as sponges and jellyfish emerged in the ocean. By 470 million years ago the first plants grew on land with the first land animals such as millipedes appearing around 428 million years ago. Mammals did not rise to ecological prominence until after the dinosaurs went extinct 65 million years ago. Humans first appeared on earth 200,000 years ago.

Explore further: Humble moss helped create our oxygen-rich atmosphere

More information: Nature Communications, DOI: 10.1038/NCOMMS14379

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16 comments

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Bart_A
1.5 / 5 (15) Feb 02, 2017
Of course this is all a bunch of BS if you don't subscribe to the extremely shaky theory of evolution. Life began by bacteria "evolving" 3.8 BY ago?? Evolving from what? Who believes this crap? This is not science. It is a made up religion.

You can have all of the oxygen and any other elements that you want, yet evolution remains a theory that has never been observed or repeated, despite scientists claims.



katesisco
1 / 5 (10) Feb 02, 2017
This will all overwhelm the existing paradigm eventually. With W Brown's book In The Beginning that notes the Earth had been 'shelled' with granite and the water below became super critical and blew out, and with W Thornhill's acknowledgement that the Earth has been 'shelled' with granite, possibly from a wash out from a dwarf star, the evidence that will push the old out is planetary granite accumulation as furnished by the JAMES WEBB telescope. If it ever makes it into orbit that is.
humy
4.6 / 5 (11) Feb 02, 2017
Who believes this crap? This is not science. It is a made up religion.

Bart_A

No, we all know it is science and it is you who believes in a load of made up religious crap and you are apparently far to stupid to see your moronic unintelligent rhetoric will convince none of us here.
You obviously unintelligent ineffectively verbally attack science because it obviously disproves your stupid religious beliefs.
Merrit
4.8 / 5 (17) Feb 02, 2017
@Bart you are confusing evolution with biogenesis. These are two very different things. Evolution does not try to explain the origin of life. Evolution takes life as a given, DNA life at that, and explains how said life became more complex and diversified etc.
Biogenesis is the theory for how life came to be on this planet and is still unknown, an open question. But, we have ideas for how we think it may have come to be.
Vidyaguy
5 / 5 (4) Feb 02, 2017
Nicely said, Merrit, properly avoiding confrontation or intellectual chest-pounding.
Osiris1
not rated yet Feb 03, 2017
Panspermia! The most likely culprit
arcmetal
3.7 / 5 (3) Feb 03, 2017
Of course this is all a bunch of BS if you don't subscribe to the extremely shaky theory of evolution. Life began by bacteria "evolving" 3.8 BY ago?? Evolving from what? Who believes this crap? This is not science. It is a made up religion.

You can have all of the oxygen and any other elements that you want, yet evolution remains a theory that has never been observed or repeated, despite scientists claims.

What? If you had said that the Earth was hollow and filled with crab people, it might have been more believable.
proxima_physorg
1 / 5 (1) Feb 03, 2017
this means on other planets that are almost completely water-covered, intelligent life can never evolve
Merrit
5 / 5 (1) Feb 03, 2017
@proxima it depends on the planet I would say. There was a oxygen sink thar needed to be overcome before a surplus could be made. I would think an intelligent ocean species would have trouble progressing technologically though because it tough to have a furnace under water to smelt with and create basic tools.
FredJose
1 / 5 (7) Feb 06, 2017
No, we all know it is science and it is you who believes in a load of made up religious crap

Really? Science? How does your science create an abstract entity [information] from purely materialistic processes? Life concerns INFORMATION. Without that information life cannot exist. So WHERE did the information come from?
In case you do not understand the fact of information - think signalling - coding and decoding - basic structural dimensional specification, basic functional specification and integration, material discovery, transport and transformation otherwise known as digestion and assimilation. Your abiogenesis myth and darwinian evolutionary religious FAITH suppresses the truth and is dictatorially oppressive.
FredJose
1 / 5 (7) Feb 06, 2017
This helped animals colonise the land, leading eventually to the evolution of mankind.

It did not - evolution is not possible: natural selection and random mutations are unable to CREATE the required complexity in the first instance and in the second instance whatever gets created is mostly destructive and life-threatening.
Right now it is VERY clear that all the genomes are in rapid devolution, i.e. they are falling apart at the seams because of the accumulation of genetic errors. This is REAL observational science confirmed by both sides of this divide - John Sanford for the creationists and Alexey Kondrashov for the evolutionists. Some people are now trying to downplay this genetic entropy by saying it's not as bad as expected - but they don't say the obvious - there's no improvement, only a rapid downhill to extinction. The error rates are such that we are not expected to last more than 10k years. So how can it be possible to have "evolved" over billions of years.
Whydening Gyre
5 / 5 (2) Feb 06, 2017
- evolution is not possible: natural selection and random mutations are unable to CREATE the required complexity in the first instance

It's not created. It's built
and in the second instance whatever gets created is mostly destructive and life-threatening.

Like many humans? Pretty good proof that it isn't intelligence driving it.
Notice it doesn't work in seamless straight line. Fits and starts, large and small, successful and not successful, driven by environmental variation..
Also notice that big changes only occur in the most active and, thusly challenging, environments...
Change happens. Adapt or die...
derphys
not rated yet Feb 08, 2017
More exactly a multicellular life started clearly with fossils 2 billions years ago big discovery in Gabon, but the question is why this life stopped over one and half billion years with nearly no oxygen ????
http://www2.cnrs....1753.htm
May be this explanation, no complex plants on land is valid ?
derphys
not rated yet Feb 08, 2017
Evolution is not a theory, but a reality with many experimental proofs with many fossils over billions years along this very difficult evolution !!
A multicellular life started clearly with fossils 2 billions years ago big discovery in Gabon,
http://www2.cnrs....1753.htm
And other multicellular fossils 1.5 billion years old in China :
http://www.nature...mms11500
Life has been very long to expand with the very slow beginning of the exponential expansion, because it is extremely slow to obtain by chance an efficient life..

humy
5 / 5 (2) Feb 10, 2017
"...Evolution is not a theory, but a reality .."

Be careful here.
I believe the more correct words would be something like;

"...Evolution is not merely a theory, but a proven theory thus reality .."
humy
5 / 5 (2) Feb 10, 2017
No, we all know it is science and it is you who believes in a load of made up religious crap

Really? Science? How does your science create an abstract entity [information] from purely materialistic processes? .

The information in the modern genetic code obviously came about by a combination of random mutation and natural selection.
This is extremely easy to understand and no mystery and we have evidence for this.
Note both random mutation and natural selection are purely materialistic processes and not requiring any Goddidit; again, this is no mystery.
What you find so hard to understand here?
This is extremely easy to comprehend; so easy I remember I understood it when I was 5 years old.

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