When Did Life Likely Emerge on Earth in an RNA‐First Process?

Benner, Steven A.; Bell, Elizabeth A.; Biondi, Elisa; Brasser, R.; Carell, Thomas; Kim, Hyo‐Joong; Mojzsis, Stephen J.; Omran, Arthur; Pasek, Matthew A.; Trail, Dustin

doi:10.1002/syst.202000009

Cited by 20 publications

(21 citation statements)

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“…Potential pathways for RNA formation on the early Earth suggest that a major post-Moon forming impact was necessary to provide a suitably reducing atmosphere, which then facilitated rapid RNA formation by ca. 4.36 Ga (Benner et al, 2020).…”

Section: Primordial Earth: Initial Felsic Crust Formation-ca 445-380 Gamentioning

confidence: 99%

Secular Evolution of Continents and the Earth System

Cawood

Chowdhury

Mulder

et al. 2022

Reviews of Geophysics

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Our planet is unique in the solar system in having a bimodal distribution of crustal types (continental and oceanic), the presence of liquid water at its surface, an oxygenated atmosphere, and a prolific and diverse biosphere. The evolving yet linked nature of these elements, across the range of spatial and temporal scales that operate on the planet, indicates complex and dynamic cycling between the solid (lithosphere, mantle, and core) and surficial (oceans, atmosphere, and biosphere) reservoirs. This linked evolution occurs in response to heat dissipation from the planet's interior, modulated by input of solar energy to the surficial reservoirs. During its very early history the Earth lacked these crustal and surficial features and, after initial accretion from the solar nebula, likely consisted of a magma ocean (e.g., Elkins-Tanton, 2012). Cooling, density settling, and crystallization resulted in rapid differentiation of the Earth, perhaps over a few tens of millions of years, and included formation of core, mantle, proto-crust, and atmosphere (Figure 1; Elkins-Tanton, 2008. Establishing the cascading succession of

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Section: Primordial Earth: Initial Felsic Crust Formation-ca 445-380 Gamentioning

confidence: 99%

Secular Evolution of Continents and the Earth System

Cawood

Chowdhury

Mulder

et al. 2022

Reviews of Geophysics

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“…Over the past half-century, a great deal of experimental effort has been devoted to attempts to demonstrate a feasible prebiotic synthesis of canonical RNA nucleotides, the initial oligomerization of these nucleotides, and the nonenzymatic, template-directed replication of RNA oligomers. Despite this effort, no scenario exists that displays all of these phenomena . The results reported here suggest that alternative ancestral proto-nucleotides and oligomers have the potential to resolve some of these difficulties.…”

Section: Discussionmentioning

confidence: 89%

Depsipeptide Nucleic Acids: Prebiotic Formation, Oligomerization, and Self-Assembly of a New Proto-Nucleic Acid Candidate

et al. 2021

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The mechanism by which informational polymers first formed on the early earth is currently unknown. The RNA world hypothesis implies that RNA oligomers were produced prebiotically, before the emergence of enzymes, but the demonstration of such a process remains challenging. Alternatively, RNA may have been preceded by an earlier ancestral polymer, or proto-RNA, that had a greater propensity for self-assembly than RNA, with the eventual transition to functionally superior RNA being the result of chemical or biological evolution. We report a new class of nucleic acid analog, depsipeptide nucleic acid (DepsiPNA), which displays several properties that are attractive as a candidate for proto-RNA. The monomers of depsipeptide nucleic acids can form under plausibly prebiotic conditions. These monomers oligomerize spontaneously when dried from aqueous solutions to form nucleobase-functionalized depsipeptides. Once formed, these DepsiPNA oligomers are capable of complementary self-assembly and are resistant to hydrolysis in the assembled state. These results suggest that the initial formation of primitive, self-assembling, informational polymers on the early earth may have been relatively facile if the constraints of an RNA-first scenario are relaxed.

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“…56 Although a large impact would have been catastrophic for any life that was already present on Earth, it could have potentially seeded Earth's postimpact surface with fatty acids and other necessary biomolecules, enabling life to subsequently emerge. 57 Ground-breaking experiments by Nooner and Oro modeled a postimpact scenario for fatty acid synthesis. 23,50 It remains uncertain how the yield of fatty acids depends on experimental parameters such as partial pressure and temperature.…”

Section: Surfacesmentioning

confidence: 99%

“…Catalytic metal surfaces would be required to produce fatty acids, so future research in this area will be especially valuable if it constrains the location and quantity of reduced metals after such impacts . Although a large impact would have been catastrophic for any life that was already present on Earth, it could have potentially seeded Earth’s postimpact surface with fatty acids and other necessary biomolecules, enabling life to subsequently emerge …”

Section: Catalysis Of Fatty Acid Synthesis By Metal Surfacesmentioning

confidence: 99%

“…Next, we consider fatty acid synthesis on metal surfaces in the wake of a large Vesta-sized (∼10 20 kg) asteroid impact on the early Earth. Such an impact would deliver iron to Earth’s surface, which could both act as a catalyst for fatty acid synthesis and generate a H 2 -rich atmosphere by reactions with steam from the vaporized ocean, as in eq : normalH 2 normalO + Fe → normalH 2 + FeO An H 2 -rich atmosphere appears to be required for fatty acid synthesis by metal catalysts (Table ). Such a massive asteroid impact would generate a high enough surface temperature to destroy most organic molecules on Earth; then, as the Earth cooled, the synthesis of fatty acids could occur in the H 2 -rich atmosphere.…”

Section: Estimating the Contribution Of Each Source To The Early Eart...mentioning

confidence: 99%

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Plausible Sources of Membrane-Forming Fatty Acids on the Early Earth: A Review of the Literature and an Estimation of Amounts

Cohen

Todd

Wogan

et al. 2022

ACS Earth Space Chem.

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The first cells were plausibly bounded by membranes assembled from fatty acids with at least 8 carbons. Although the presence of fatty acids on the early Earth is widely assumed within the astrobiology community, there is no consensus regarding their origin and abundance. In this Review, we highlight three possible sources of fatty acids: (1) delivery by carbonaceous meteorites, (2) synthesis on metals delivered by impactors, and (3) electrochemical synthesis by spark discharges. We also discuss fatty acid synthesis by UV or particle irradiation, gas-phase ion–molecule reactions, and aqueous redox reactions. We compare estimates for the total mass of fatty acids supplied to Earth by each source during the Hadean eon after an extremely massive asteroid impact that would have reset Earth’s fatty acid inventory. We find that synthesis on iron-rich surfaces derived from the massive impactor in contact with an impact-generated reducing atmosphere could have contributed ∼102 times more total mass of fatty acids than subsequent delivery by either carbonaceous meteorites or electrochemical synthesis. Additionally, we estimate that a single carbonaceous meteorite would not deliver a high enough concentration of fatty acids (∼15 mM for decanoic acid) into an existing body of water on the Earth’s surface to spontaneously form membranes unless the fatty acids were further concentrated by another mechanism, such as subsequent evaporation of the water. Our estimates rely heavily on various assumptions, leading to significant uncertainties; nevertheless, these estimates provide rough order-of-magnitude comparisons of various sources of fatty acids on the early Earth. We also suggest specific experiments to improve future estimates. Our calculations support the view that fatty acids would have been available on the early Earth. Further investigation is needed to assess the mechanisms by which fatty acids could have been concentrated sufficiently to assemble into membranes during the origin of life.

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When Did Life Likely Emerge on Earth in an RNA‐First Process?

Cited by 20 publications

References 0 publications

Secular Evolution of Continents and the Earth System

Secular Evolution of Continents and the Earth System

Depsipeptide Nucleic Acids: Prebiotic Formation, Oligomerization, and Self-Assembly of a New Proto-Nucleic Acid Candidate

Plausible Sources of Membrane-Forming Fatty Acids on the Early Earth: A Review of the Literature and an Estimation of Amounts

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