VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
2. The Origins of Life
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.
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)
Szostak, Jack. Systems Chemistry on Early Earth. Nature. 459/171, 2009. A commentary on the paper “Synthesis of Activated Pyrimidine Ribonucleotides in Prebiotically Plausible Conditions” in the same issue by University of Manchester chemists Matthew Powner, Beatrice Gerland and John Sutherland which is seen as a breakthrough in being able to explain how RNA “informational polymers” first formed via phosphate reactants and catalysts. Its importance was also noted by Nicholas Wade in “Chemist Shows How RNA Can Be the Starting Point for Life” in the N. Y. Times for May 14, 2009. But even more significance might accrue because nature’s primordial chemistry then seems primed for such “spontaneous assembly,” as the quote avers with British understatement. See also a later article by Wade in the NYT for June 16, 2009 on this and other Origin of Life advances.
Our findings suggest that the prebiotic synthesis of activated pyrimidine nucleotides should be viewed as predisposed. This predisposition would have allowed the synthesis to operate on the early Earth under geochemical conditions suitable for the assembly sequence. (Powner, et al 242)
Szostak, Jack. The Narrow Road to the Deep Past: In Search of the Chemistry of the Origin of Life. Angewandte Chemie International. 56/37, 2017. The Nobel chemist (2009) at the Howard Hughes Medical Institute, Center for Computational and Integrative Biology, Boston writes a popular update on his own work and on the long project to recover and quantify how living, evolving systems came to be. A salient aspect is the appearance of membrane-bounded protocell vesicles, which then play a role in forming vital RNA polymerase replicators. Once life got going, other catalytic biochemicals could complexify toward enzymes, metabolisms all the way to we curious curators.
The sequence of events that gave rise to the first life on our planet took place in the Earth's deep past, seemingly beyond our reach. Understanding the processes that led to the chemical building blocks of biology and how these molecules self‐assembled into cells that could grow, divide and evolve, nurtured by a rich and complex environment, seems insurmountably difficult. And yet, to my own surprise, simple experiments have revealed robust processes that could have driven the growth and division of primitive cell membranes. Even our efforts to combine replicating compartments and genetic materials into a full protocell model have moved forward in unexpected ways. Fortunately, many challenges remain, so the future in this field is brighter than ever! (Abstract)
Takeuchi, Nobuto and Paulien Hogeweg. Multilevel Selection in Models of Prebiotic Evolution II: A Direct Comparison of Compartmentalization and Spatial Self-Organization. PLoS Computational Biology. 5/10, 2010. In a follow up to their 2003 paper herein, Utrecht University bioinformaticians offer new pathways to help perceive and factor in these real, prior, endemic dynamics and resultant nested emergences for the welling evolutionary revision to complement and augment post selection.