ELSI organize some events around the theme "Origins of Life" form of a few seminars followed by a three-day round-table workshop.

June 12, 10:00:

Speaker: Nick Hud, Georgia Institute of Technology
Title: Self-replication and the RNA World Hypothesis
Abstract: Genetic information and control of chemical reactions are two fundamental characteristics of life. The discovery that RNA can catalyze chemical reactions, as well as function as a genetic material, has focused much attention on the hypothesis that RNA came before DNA and proteins. Some researchers have even suggested that RNA was the first polymer of life, and that RNA-based replicators spontaneously emerged on the early Earth. Given the difficulties associated with forming RNA polymers by plausible prebiotic reactions, our laboratory is exploring the hypothesis that the chemical structure of RNA is the product of evolution, and that RNA is a latter member of a continuous linkage of informational polymers that are descendants of an ancestral RNA-like polymer (or proto-RNA) that spontaneously assembled from molecular building blocks on the early Earth. We are also exploring how regular geological cycles (e.g. day-night, tidal, seasonal) could have driven pre-RNA polymers between times of replication and functional activity, and thereby promoted the buildup of
such polymers and facilitated the early evolution of functional sequences.

June 12, 11:00:

Speaker: Rogier Braakman, Santa Fe Institute
Title: A metabolic tree of life
Abstract: Metabolism generates all monomer building blocks of living systems, and embeds the biosphere within geochemistry. The early evolutionary history of metabolism thus provides important context for understanding the emergence of life. Integrating metabolic and phylogenetic reconstructions, we can start building a metabolic tree of life. Such a tree consists of lineages of functional metabolic networks, reaching from earlier and more universal features of metabolism near the base of the tree, to highly varied and specialized metabolisms at its leaves. I will discuss a tree of carbon-fixation -- the metabolic foundation of the biosphere -- that relates all extant pathways to a single ancestral form. Our results identify clear environmental driving forces for most divergences, and suggest that biogeochemical perturbations acting on carbon-fixation resulted in much of the deep structure in the tree of life. Finally, the reconstructed root network contains features that suggest why it may have been selected among alternative abiotic networks, as well as hints on the mapping between early geochemistry and early metabolism. Together these results highlight key physical-chemical constraints that have operated continuously on the biosphere, and that plausibly reach back prior to the emergence of life.

June 12, 14:00:

Speaker: Omer Markovitch, Weizmann Institute of Science
Titel: Compositional Lipid Assemblies as Evolving Proto Cells
Abstract: Life is complex, and its origin is about how sufficient chemical complexity emerged to afford replication. A crucial aspect of replication is the faithful transmission of sufficient information to progeny. The graded autocatalysis replication domain (GARD) model, in the realm of the lipid world scenario, offers a possible route for such pursuit. In this framework, non-covalent assemblies of amphiphiles, such as lipid micelles or vesicles, can acquire adequate endogenous complexity, mediated by a set of catalyzed chemical reactions akin to metabolism. Our computer simulations show that GARD assemblies carry and transmit compositional information through catalyzed homeostatic growth followed by random fission. Key in GARD dynamics are composomes, spontaneously-forming replication-prone quasi-stationary states. A group of composomes, gleaned by clustering, is termed compotype, and may be regarded as species in the framework of lipid world and GARD. Indeed, such GARD species were recently shown to display a significant measure of Darwinian evolution, and their populations are capable of displaying ecological dynamics. Thus, the GARD formalism allows one to delineate a
well-defined chemically-rigorous path from random chemical environments ("primordial soup") to replicating and evolving protocellular structures. Importantly, it also affords a quantitative delineation of a transition from compositional to polymer-based sequential information, thus supporting the concept of metabolism as a precursor for RNA world.

June 12, 15:00:

Speaker: Nigel Goldenfeld, University of Illinois at Urbana-Champaign
Title: Universal biology and the evolution of life prior to LUCA.
Abstract: Relics of early life, preceding even the last universal common ancestor of all life on Earth, are present in the structure of the modern day canonical genetic code -- the map between DNA sequence and amino acids that form proteins. The code is not random, as often assumed, but instead is now known to have certain error minimisation properties. How could such a code evolve, when it would seem that mutations to the code itself would cause the wrong proteins to be translated, thus killing the organism? Using digital life simulations, I show how a unique and optimal genetic code can emerge over evolutionary time, but only if horizontal gene transfer -- a network effect -- was a much stronger characteristic of early life than it is now. These results suggest a natural scenario in which evolution exhibits three distinct dynamical regimes, differentiated respectively by the way in which information flow, genetic novelty and complexity emerge. Possible observational signatures of these predictions are discussed. Finally, I argue that this work is an explicit example of how universal principles about the emergence of life can be extracted from the instantiation of life that we have on Earth.

June 13-14 10:00-12:00, 14:00-17:00: Open discussions