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I’m surprised by this statement. Here is a quote from Nick Lane’s great text: Power, Sex, Suicide (p 153): > The early Earth, as envisaged by [Michael J] Russ

I’m surprised by this statement. Here is a quote from Nick Lane’s great text: Power, Sex, Suicide (p 153): > The early Earth, as envisaged by [Michael J] Russell, is a giant electrochemical cell, which depends in the power of the sun to oxidize the oceans. UV rays split water and oxidize iron. Hydrogen, released from the water, is so light that it is not retained by gravity, and evaporates into space. The oceans become gradually oxidized relative to the more reduced conditions of the mantle.” Lanes cites this paper “On the origins of cells: A hypothesis for the evolutionary transition from abiotic to nucleated cells”, 2003, by Martin and Russell https://pubmed.ncbi.nlm.nih.gov/12594918/ https://pubmed.ncbi.nlm.nih.gov/12594918/ Am I missing something? This text forces me to assume that solar UV splitting water is the cause of the O2 atmospheric flooding.

robwwilliams 2y ago
And not true at all that all organisms need O2 to pump protons. Microbes have quite a few alternative ways. Even we do when we run the Krebs cycle backwards.
lordgrenville 2y ago
I'm currently reading another of his books, Oxygen: The Molecule that made the World, which unsurprisingly has lots more about this topic.
jmcqk6 2y ago
I'm a huge fan of Nick Lane, and I'm not an expert, so I may have misunderstood. I have not read "Power, Sex, Suicide" but have read "The vital question", "transformer," and most importantly in this context, "Oxygen." My understanding, which could absolutely be wrong, is that there are pathways to where Oxygen can be generated without life, but for it to be maintained at high levels of concentration over time, that takes life. I would definitely defer to whatever Nick Lane has to say about it.
philipkglass 2y ago
Here's the full text of the "On the origins of cells..." paper via sci-hub: https://sci-hub.se/10.1098/rstb.2002.1183 https://sci-hub.se/10.1098/rstb.2002.1183 There's nothing in it about ultraviolet splitting of water or oceanic oxidation. If Nick Lane meant to paraphrase the paper in that cited passage, he did a poor job. Direct UV homolysis of water to release hydrogen requires a photon with more than 6.5 electron volts of energy [1], corresponding to a wavelength of 190 nm or shorter. As you can see here, solar irradiance is extremely low at wavelengths shorter than 240 nm: https://en.wikipedia.org/wiki/Solar_irradiance#/media/File:Solar_spectrum_en.svg https://en.wikipedia.org/wiki/Solar_irradiance#/media/File:S... There isn't enough energetic UV radiation emitted from the sun to directly oxygenate the Earth via water homolysis. It might be possible for an exoplanet in orbit around a hotter star that emits more energetic UV. EDIT: I forgot to account that the sun may have had a very different UV profile billions of years ago. "UV radiation from the young Sun and oxygen and ozone levels in the prebiological palaeoatmosphere" https://sci-hub.se/10.1038/296816a0 https://sci-hub.se/10.1038/296816a0 UV measurements of young T-Tauri stars, resembling the Sun at an age of a few million years, have recently been made with the International Ultraviolet Explorer. They indicate that young stars emit up to 10^4 times more UV than the present Sun. [1] https://en.wikipedia.org/wiki/Photocatalytic_water_splitting#Concepts https://en.wikipedia.org/wiki/Photocatalytic_water_splitting...
topaz0 2y ago
To reduce hydrogen, something needs to be oxidized, but it doesn't need to be oxygen. E.g. you could get more metal oxides. Not my field exactly, so I don't know either relative abundances of different stuff in early oceans or the exact ranking of which would be most readily oxidized, but that could explain the discrepancy. Edit: rereading the passage you quoted does make me think that metal oxides are the important factor here.

robwwilliams 2y ago

And not true at all that all organisms need O2 to pump protons. Microbes have quite a few alternative ways. Even we do when we run the Krebs cycle backwards.

lordgrenville 2y ago

I'm currently reading another of his books, Oxygen: The Molecule that made the World, which unsurprisingly has lots more about this topic.

jmcqk6 2y ago

I'm a huge fan of Nick Lane, and I'm not an expert, so I may have misunderstood. I have not read "Power, Sex, Suicide" but have read "The vital question", "transformer," and most importantly in this context, "Oxygen." My understanding, which could absolutely be wrong, is that there are pathways to where Oxygen can be generated without life, but for it to be maintained at high levels of concentration over time, that takes life. I would definitely defer to whatever Nick Lane has to say about it.

philipkglass 2y ago

Here's the full text of the "On the origins of cells..." paper via sci-hub: https://sci-hub.se/10.1098/rstb.2002.1183 https://sci-hub.se/10.1098/rstb.2002.1183 There's nothing in it about ultraviolet splitting of water or oceanic oxidation. If Nick Lane meant to paraphrase the paper in that cited passage, he did a poor job. Direct UV homolysis of water to release hydrogen requires a photon with more than 6.5 electron volts of energy [1], corresponding to a wavelength of 190 nm or shorter. As you can see here, solar irradiance is extremely low at wavelengths shorter than 240 nm: https://en.wikipedia.org/wiki/Solar_irradiance#/media/File:Solar_spectrum_en.svg https://en.wikipedia.org/wiki/Solar_irradiance#/media/File:S... There isn't enough energetic UV radiation emitted from the sun to directly oxygenate the Earth via water homolysis. It might be possible for an exoplanet in orbit around a hotter star that emits more energetic UV. EDIT: I forgot to account that the sun may have had a very different UV profile billions of years ago. "UV radiation from the young Sun and oxygen and ozone levels in the prebiological palaeoatmosphere" https://sci-hub.se/10.1038/296816a0 https://sci-hub.se/10.1038/296816a0 UV measurements of young T-Tauri stars, resembling the Sun at an age of a few million years, have recently been made with the International Ultraviolet Explorer. They indicate that young stars emit up to 10^4 times more UV than the present Sun. [1] https://en.wikipedia.org/wiki/Photocatalytic_water_splitting#Concepts https://en.wikipedia.org/wiki/Photocatalytic_water_splitting...

topaz0 2y ago

To reduce hydrogen, something needs to be oxidized, but it doesn't need to be oxygen. E.g. you could get more metal oxides. Not my field exactly, so I don't know either relative abundances of different stuff in early oceans or the exact ranking of which would be most readily oxidized, but that could explain the discrepancy. Edit: rereading the passage you quoted does make me think that metal oxides are the important factor here.