I’ve read Nick Lane’s book, but I’m not familiar with Eric Smith’s stuff (yet).
Lane agrees that life started from a geochemical disequilibrium, in Lane’s model it’s serpentinization.
Lane’s book spends a lot of time talking about the Acetyl-CoA cycle, which is a key part of the Citric Acid cycle, as well as many other metabolic cycles. But he doesn’t mention the reverse Krebs cycle or adenine specifically, AFAICT. He cites Eric Smith favorably as going into more details on the specific biochemistry involved.
Regarding membranes, his model is that the first membranes were very leaky with respect to ions. Which is a good thing in the disequilibrium environment, since otherwise the cell would get too full of ions, and die! But there are two big problem for cells with such membranes: 1. their gradient will quickly equilibriate if they leave the sea vent, thus killing them. 2. Evolving a less leaky membrane will reduce their ability to use the sea-vent gradient, and thus by itself will not be selected for. A proton pump will not give an advantage in this case (the argument is a bit complex). The key is that a Sodium antiporter pump needed to come after the leaky membrane. This by itself gives an advantage, by also creating an Na+ gradient across the membrane, and this advantage is strengthened by making the membrane incrementally less leaky. (Lane explicitly claims that the oceans were high in Sodium ions, and low in Potassium ions 4 billion years ago, FWIW.)
But just the Sodium pump wasn’t enough to allow the cells to survive autonomously, since it trades positive ions for positive ions one to one. However, it now makes it advantageous to evolve a proton pump. And that was what finally facilitated the ability for cells to become fully autonomous. He goes on to claim that the direction the proton pump was “installed” across the membrane creates different problems, and that Bacteria and Archea are the result of this happenstance.
If I had a hunch it would route through the idea of metal atoms that fit into larger enzymes like rock knives wielded by squishy caveman hands.
As wikipedia says of inorganic biochemical co-factors:
In nutrition, the list of essential trace elements reflects their role as cofactors. In humans this list commonly includes iron, magnesium, manganese, cobalt, copper, zinc, and molybdenum.
So the thing I would naively do, to find candidate minerals, would be to try to sift conserved co-factors, especially with a focus on ribozymes that do the same trick, and then these “metalloribozymes” (some of which do exist in evolved systems still) might suggest typical mineral environments where things first started and never stopped being essential…
...but I don’t seem much mention of Olivine playing well with copper or zinc, and [manganese olivine] goes to its own name: Tephroite. But there was no mention of Tephroite in the review.
So this is where my own naive priors would send me looking: for minerals full of elemental cofactors common to ancient metalloribozymes. Lots of data sifting seems likely to be useful, over ribozyme and enzyme databases, and mineral databases, which I have not done.
Did Nick Lane do this kind of data sifting to find the name “Olivine”, or did he use some other method?
One idea is that he got the name from the literature, and perhaps cites whoever proposed Olivine? When I search [olivine biogenesis] I get Serpentinization results which echo the link you offered (and youtube on [serpentization] gives a fun experimental video that is interesting but sheds no particular light for me).
Synthesizing this… maybe the practical upshot is just “most normal mantle material reacting with seawater” could be loosely called “something-like-olivine turning to something-like-serpentine” and since there is so much mantle, and so much seawater, priors say that “this general reaction” is the key reaction at a high and fuzzy level of description. Maybe?
It looks like he got it from Mike Russell, though he disagrees with Russell on the details.
Regarding cofactors, the important thing (in Lane’s version of this model) about serpentinization is that it is alkaline. This would cause iron to precipitate out (as iron hydroxides and iron sulphates), and dissolve minerals such as nickel and molybdenum.
He points out nickel-doped greigite (Fe5NiS8) as a mineral with a crystal structure similar to several ancient metalloribozymes, and which he thinks was likely to have deposited on the walls of pores in the rock (serpentine?).
I’ve read Nick Lane’s book, but I’m not familiar with Eric Smith’s stuff (yet).
Lane agrees that life started from a geochemical disequilibrium, in Lane’s model it’s serpentinization.
Lane’s book spends a lot of time talking about the Acetyl-CoA cycle, which is a key part of the Citric Acid cycle, as well as many other metabolic cycles. But he doesn’t mention the reverse Krebs cycle or adenine specifically, AFAICT. He cites Eric Smith favorably as going into more details on the specific biochemistry involved.
Regarding membranes, his model is that the first membranes were very leaky with respect to ions. Which is a good thing in the disequilibrium environment, since otherwise the cell would get too full of ions, and die! But there are two big problem for cells with such membranes: 1. their gradient will quickly equilibriate if they leave the sea vent, thus killing them. 2. Evolving a less leaky membrane will reduce their ability to use the sea-vent gradient, and thus by itself will not be selected for. A proton pump will not give an advantage in this case (the argument is a bit complex). The key is that a Sodium antiporter pump needed to come after the leaky membrane. This by itself gives an advantage, by also creating an Na+ gradient across the membrane, and this advantage is strengthened by making the membrane incrementally less leaky. (Lane explicitly claims that the oceans were high in Sodium ions, and low in Potassium ions 4 billion years ago, FWIW.)
But just the Sodium pump wasn’t enough to allow the cells to survive autonomously, since it trades positive ions for positive ions one to one. However, it now makes it advantageous to evolve a proton pump. And that was what finally facilitated the ability for cells to become fully autonomous. He goes on to claim that the direction the proton pump was “installed” across the membrane creates different problems, and that Bacteria and Archea are the result of this happenstance.
Thanks! Does he explain “why Olivine”?
If I had a hunch it would route through the idea of metal atoms that fit into larger enzymes like rock knives wielded by squishy caveman hands.
As wikipedia says of inorganic biochemical co-factors:
So the thing I would naively do, to find candidate minerals, would be to try to sift conserved co-factors, especially with a focus on ribozymes that do the same trick, and then these “metalloribozymes” (some of which do exist in evolved systems still) might suggest typical mineral environments where things first started and never stopped being essential…
...but I don’t seem much mention of Olivine playing well with copper or zinc, and [manganese olivine] goes to its own name: Tephroite. But there was no mention of Tephroite in the review.
So this is where my own naive priors would send me looking: for minerals full of elemental cofactors common to ancient metalloribozymes. Lots of data sifting seems likely to be useful, over ribozyme and enzyme databases, and mineral databases, which I have not done.
Did Nick Lane do this kind of data sifting to find the name “Olivine”, or did he use some other method?
One idea is that he got the name from the literature, and perhaps cites whoever proposed Olivine? When I search [olivine biogenesis] I get Serpentinization results which echo the link you offered (and youtube on [serpentization] gives a fun experimental video that is interesting but sheds no particular light for me).
Synthesizing this… maybe the practical upshot is just “most normal mantle material reacting with seawater” could be loosely called “something-like-olivine turning to something-like-serpentine” and since there is so much mantle, and so much seawater, priors say that “this general reaction” is the key reaction at a high and fuzzy level of description. Maybe?
It looks like he got it from Mike Russell, though he disagrees with Russell on the details.
Regarding cofactors, the important thing (in Lane’s version of this model) about serpentinization is that it is alkaline. This would cause iron to precipitate out (as iron hydroxides and iron sulphates), and dissolve minerals such as nickel and molybdenum.
He points out nickel-doped greigite (Fe5NiS8) as a mineral with a crystal structure similar to several ancient metalloribozymes, and which he thinks was likely to have deposited on the walls of pores in the rock (serpentine?).