VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
2. The Origins of Life
Schuster, Peter and Peter Stadler. Networks in Molecular Evolution. Complexity. 8/1, 2003. With a subtitle “A Common Theme at All Levels,” this paper claims that the way biochemicals evolved into organic complexity is by a hierarchy of autocatalytic systems.
Schwartzman, David and Charles Lineweaver. The Hyperthermophilic Origin of Life Revisited. Biochemical Society Transactions. 32/2, 2004. Since microorganisms are now found exist at temperatures exceeding 1200 C, the case for a hot biogenesis and widespread prevalence of life grows stronger.
Seckbach, Joseph, ed. Origins: Genesis, Evolution and Diversity of Life. Dordrecht: Kluwer Academic, 2004. Not yet seen, here is an excerpt from the publisher’s website. This new volume of "Origins: Genesis, Evolution and Biodiversity of Microbial Life in the Universe" is the sixth unit of the book series "Cellular Origins, Life in Extreme Habitats and Astrobiology" edited by Joseph Seckbach. Forty eminent scientists review their studies in the fields of Life from the beginning to the "Fact of Life." The history of Origin of Life and Astrobiology is well covered by these authors. Reviews cover the standard and alternative scenarios of the genesis of Life, while the chapters of "The First Cells" leading to the biodiversity and extremophiles of microbial Life.
Seoane, Luis and Ricard Sole. Information Theory, Predictability and the Emerge of Complex Life. Royal Society Open Science. February, 2018. MIT Center for Brains, Minds + Machines (Google) and ICREA-Complex Systems Lab, Universitat Pompeu Fabra, Barcelona polymaths propose a broader synthesis to help quantify and explain how genomic life came to evolve and arise by way of dynamic ecological interactivities.
Despite the obvious advantage of simple life forms capable of fast replication, different levels of cognitive complexity have been achieved by living systems in terms of their potential to cope with environmental uncertainty. Against the inevitable cost associated with detecting environmental cues and responding to them in adaptive ways, we conjecture that the potential for predicting the environment can overcome the expenses associated with maintaining costly, complex structures. We present a minimal formal model grounded in information theory and selection, in which successive generations of agents are mapped into transmitters and receivers of a coded message. Our agents are guessing machines and their capacity to deal with environments of different complexity defines the conditions to sustain more complex agents. (Abstract)
Shapiro, Robert. A Simpler Origin for Life. Scientific American. June, 2007. The veteran NYU researcher moves beyond the Replicator First persuasion, via the sudden appearance of a large self-copying molecule, in favor of life’s metabolic dynamics as initially expressed by energy-driven networks of small molecules. By so doing, still another recognition that interrelations between objects are equally relevant is achieved. The journal article is paired with an interactive, longer online version. At this SA blog, reviewers can ask questions, some of which have been answered in print. A good example of how real science works as widely collaborative and in constant review.
Shapiro, Robert. Small Molecule Interactions were Central to the Origin of Life. Quarterly Review of Biology. 81/2, 2006. The New York University researcher highlights this feature towards the convergent understanding of how cellular organisms came to be.
I have provided only a framework, and not a specific recipe, to illustrate how a coupled free-energy source could initiate the process of self-organization in a complex mixture of organic monomers. (122)
Shenhav, Barak and Doron Lancet. Prospects of a Computational Origin of Life Endeavor. Origins of Life and Evolution of the Biosphere. 34/1-2, 2004. A proposal to apply bioinformatic methods to emphasize the independent activity of “mutually catalytic networks” which served to complexify entities such as biopolymer replicator molecules.
Siebert, Charles. The Genesis Project. New York Times Sunday Magazine. September 26, 2004. The author notes that at the same time earth is beset by violent fundamentalisms, a concerted global effort, especially by NASA’s Astrobiology Institute, is revealing the true creation of life both here and in the universe. A good current summary of the collaborative enterprise.
Stankiewicz, Johanna and Lars Henning Eckardt. Chemobiogenesis 2005 and Systems Chemistry Workshop. Angewandte Chemie. 45/342, 2006. Frontier insights into an innately dynamic materiality which leads on to biological precursors are arising in central Europe as evidenced by this conference report. Leading researchers such as Peter Schuster, Eors Szathmary, Antonia Lazcano, Reza Ghadiri, and Steen Rasmussen were in attendance. A “prebiotic robustness” via the spontaneous coevolution of peptides and chemical energetics is seen to cause the emergence of homochirality (molecules of similar handedness) and nucleotides. Self-organizing catalytic networks will spawn non-Brownian self-reproducing vesicles. Such protocells can then be seen as a “supersystem” phase of a complex nonlinear chemistry. Chembiogenesis 2007 is to be held in Dubrovnik, Croatia in May.
Stubbs, Trent, et al. A Plausible Metal-free Ancestral Analogue of the Krebs cycle Composed Entirely of Alpha-ketoacids. Nature Chemistry. October, 2020. NSF-NASA Center for Chemical Evolution (Google) researchers including Greg Springsteen (Furman University) delve deeper into early biochemical phases so to reconstruct endemic ways that life’s emergent course could have plausibly taken place. Our late observance and accomplishment again implies a phenomenal fertility of an organically procreative ecosmos.
Efforts to decipher the prebiotic roots of metabolic pathways have focused on recapitulating modern biological transformations, with metals serving in place of cofactors and enzymes. Here we show that the reaction of glyoxylate with pyruvate under mild aqueous conditions produces a series of α-ketoacid analogues of the reductive citric acid cycle without the need for metals or enzyme catalysts. The transformations proceed in the same sequence as the reverse Krebs cycle, resembling a protometabolic pathway, with glyoxylate acting as both the carbon source and reducing agent. (Abstract excerpt)
Subramanian, Hemachander and Robert Gatenby. Evolutionary Advantage of a Broken Symmetry in Autocatalytic Polymers Explains Fundamental Properties of DNA. arXiv:1605.00748. Moffitt Cancer Center and Research Institute, Tampa, FL physicians appear to describe an inherent, primordial propensity for a fertile nature to live, evolve, and learn so that one fine day cognizant peoples might be able to self-realize, heal, save, select, and enhance.
The macromolecules that encode and translate information in living systems, DNA and RNA, exhibit distinctive structural asymmetries, including homochirality or mirror image asymmetry and 3'-5' directionality, that are invariant across all life forms. Here we construct a simple model of hypothetical self-replicating polymers to show that asymmetric autocatalytic polymers are more successful in self-replication compared to their symmetric counterparts in the Darwinian competition for space and common substrates. This broken-symmetry property, called asymmetric cooperativity, arises when the catalytic influence of inter-strand bonds on their left and right neighbors is unequal. Asymmetric cooperativity also leads to simple evolution-based explanations for a number of other properties of DNA that include four nucleotide alphabet, three nucleotide codons, circular genomes, helicity, anti-parallel double-strand orientation, heteromolecular base-pairing, asymmetric base compositions, and palindromic instability, apart from the structural asymmetries mentioned above. (Abstract excerpts)
Szathmary, Eors. Coevolution of Metabolic Networks and Membranes: the Scenario of Progressive Sequestration. Philosophical Transactions of the Royal Society B. 362/1781, 2007. As the extended Abstract notes, the Eotvos University, Budapest, biologist presses the view that enclosed proto-vesicles was a crucial feature of life’s original advance. Evolution is then a story of their sequential ramification via hierarchies of wholes nested within wholes, lately a worldwide humankind. See also in the same issue Tristan Rocheleau, et al. Emergence of Protocellular Growth Laws.
Many regard metabolism as one of the central phenomena (or criteria) of life. Yet, the earliest infrabiological systems may have been devoid of metabolism: such systems would have been extreme heterotrophs. We do not know what level of complexity is attainable for chemical systems without enzymatic aid. Lack of template-instructed enzymatic catalysis may put a ceiling on complexity owing to inevitable spontaneous decay and wear and tear of chemodynamical machines. Views on the origin of metabolism critically depend on the assumptions concerning the sites of synthesis and consumption of organic compounds. If these sites are different, non-enzymatic origin of autotrophy is excluded. Whether autotrophy is secondary or not, it seems that protocell boundaries may have become more selective with time, concurrent with the enzymatization of the metabolic network. Primary heterotrophy and autotrophy imply pathway innovation and retention, respectively. The idea of metabolism–membrane coevolution leads to a scenario of progressive sequestration of the emerging living system from its exterior milieu. Comparative data on current protein enzymes may shed some light on such a primeval process by analogy, since two main ideas about enzymatization (the retroevolution and the patchwork scenarios) may not necessarily be mutually exclusive and the earliest enzymatic system may have used ribozymes rather than proteins. (1781)