The diversity of life on Earth is profound, but evidence implies it may have arisen from non-living matter only once in our deep history. What conditions and circumstances led it to begin on Earth? From what properties and pathways of chemistry can life arise naturally? And do other planets have these same chemicals and conditions, serving host to life throughout the universe?
Life’s origins can now be explored by modern science, with interdisciplinary studies that connect the formation of planets, the evolution of early Earth, the complex chemistry and delivery of the fundamental organic molecules that serve as the building blocks of early life, and how they can establish complex, self-replicating systems of cells and genetic material.
The Origins of Life speaker series, hosted by the University of Chicago Physical Sciences Division, explores these ideas with lectures by leading thinkers in their fields. The lectures are open to the public. Videos of 2020 speakers are available on our YouTube channel.
May 23, 2022, 3:45 p.m., Kent 120 or Zoom
Medical Research Council Laboratory of Molecular Biology, Cambridge
"Origins of the RNA-Protein World – Lost in Translation?"
The RNA-protein double act at the heart of biology raises several intriguing origins questions that can be addressed by prebiotic chemistry. Beyond the obvious ‘which came first?’, one can also wonder about the extent to which chemistry shaped the process of translation according to the genetic code. In this lecture I will describe some mixed hydrogen cyanide-hydrogen sulfide chemistry that produces nucleotides and amino acids. Some degree of control is necessary for this ‘cyanosulfidic’ chemistry to proceed most efficiently and ways in which environmental factors could exercise this control will be suggested. Synergies in the assembly of nucleotide and amino acid building blocks into higher order structures will then be discussed as will experimental hints of a previously proposed second genetic code. Finally, it will be shown how the strength of codon-anticodon binding likely influenced the partial initial assignment of the primary genetic code.
October 28, 2021, 2 p.m.
Phillips Professor of Astronomy, Director of the Origins of Life Initiative, Senior Advisor in the Sciences for Advanced Study, Harvard University
"Environments for the Origins of Life: Photons, Electrons, and Chemistry in Muddy Lakes"
From Mars to far beyond, our search is intensifying for evidence that life is not unique to planet Earth. I will show intersections between astro- and geochemical environments and prebiotic chemistry, which help us understand potential pathways to life - in the Solar System or exoplanets.
Nobel Laureate, 2009
Professor of Chemistry and Chemical Biology, Harvard University
Professor, Department of Genetics, Harvard Medical School
Alex Rich Distinguished Investigator, Department of Molecular Biology, Massachusetts General Hospital
Investigator, Howard Hughes Medical Institute
"The emergence of RNA from prebiotic mixtures of nucleotides”
The first genetic polymers may have been nucleic acids with significant heterogeneity in the chemistry of their nucleobases, sugar components, and backbone connectivity. I will describe our ongoing efforts to explore the chemistry, structure and properties of potentially prebiotic versions of RNA, with particular emphasis on the effects of such variations on the process of nonenzymatic RNA replication. Our findings suggest a model for the transition from early heterogeneous nucleic acids to a more homogeneous form that is closer to modern RNA.
Scientia Lecturer, Soft Matter and Biophysics Group Leader, School of Chemistry, University of New South Wales, Sydney
"Hierarchical self-assembly of model primitive cells"
This seminar will give an overview of how concepts from colloidal science and self-assembly can contribute to our understanding of how life originated from simple molecules. As a case study, the discussion will cover one process thought to be extremely favourable for the emergence of life: the ability for primitive cells to form networks and adhere, leading to robust communities that can share nutrients and genetic advantages. We first self-assemble solutions of giant unilamellar vesicles using fatty acids to use as a model system. The membranes are highly dynamic compared to phospholipid membranes, leading to interesting outcomes in self-assembly. The membranes also readily encapsulate RNA, and can store elastic energy. We will then discuss how the same membranes can also self-assemble into networks ranging from pairs to three-dimensional rafts. At first, the ability for the membranes to adhere appears confounding: like-charged membranes typically repel in the absence of fusogens or adhesives. We find that the observed aggregation can also be attributed to the dynamic properties of the bilayer system.
Associate Professor, School of Earth and Space Exploration &
Deputy Director, Beyond Center for Fundamental Concepts in Science, Arizona State University
External Faculty, Santa Fe Institute
"Inferring the 'Laws of Life' at a Planetary Scale"
In 1943, Erwin Schrodinger famously delivered a set of lectures at the Dublin Institute for Advanced Studies aiming to tackle the question “What is Life?” from the first-principles approach of a theoretical physicist. Over 70 years later, we’ve still made little headway in coming up with a general theory for what life is. While many definitions for life do exist, these are primarily descriptive, not predictive, and they have so far proved insufficient to explain the origins of life from non-living matter, or to provide rigorous constraints on what properties are universal to all life, even that on other worlds. Yet, as NASA and other space agencies are setting sights on life detection as a goal of upcoming robotic missions and space observatories, more rigorous understanding of the universal properties of living matter are becoming increasingly vital to uncover. This talk will discuss new approaches to understanding what universal principles might underlie living matter and how to generate it, based on studying biochemical networks on Earth from the scale of individual organisms to the planetary scale.
NASA Hubble-Sagan Postdoctoral Fellow, Department of the Geophysical Sciences, University of Chicago
"Astronomical insights on the delivery of organic building blocks to new worlds"
The viability of prebiotic chemistry on a nascent planet is dependent on the inventory of organic building blocks incorporated during the planet's formation, particularly the elements C,N,O,P,S. This raises the questions: how did Earth come to obtain its prebiotic precursors, and how commonly do other planets also inherit the ingredients for prebiotic chemistry? By studying the volatile/organic chemistry at play in the evolutionary progenitors of planetary systems (protostars and protoplanetary disks), we gain a valuable window into the initial chemical conditions of planet formation. This talk will discuss advances in characterizing the organic chemistry ongoing during the assembly of planetary systems, largely thanks to the unprecedented sensitivity and spatial resolution of the ALMA interferometer. Despite recent progress, we still cannot directly probe the volatile material relevant for terrestrial planet formation, and this discussion will highlight how complementary simulations and laboratory experiments have been critical for interpreting the observations. We will also discuss future avenues for progress, in particular the upcoming James Webb Space Telescope, which will directly probe the composition of icy material relevant for planet and planetesimal formation.
Associate Director for Strategic Science, NASA Goddard Space Flight Center
"Meteorite Delivery of Prebiotic Organics: An Inventory for the Origin of Life"
Meteorites provide a record of the chemical processes that occurred in the early solar system before life began on Earth. The delivery of complex organic compounds by carbonaceous chondrites to the early Earth and other planetary bodies could have been an important source of prebiotic organic compounds required for the emergence of life. Of particular interest is the study of meteoritic amino acids and their enantiomeric compositions since these molecules are the monomers of proteins common to all life on Earth. The single chirality observed in biological molecules - left-handed amino acids and right-handed sugars - is a property important for molecular recognition processes and is thought to be a prerequisite for life. In contrast to biology, all known non-biological reactions result in equal mixtures of left- and right-handed (L = D) amino acids and sugars. Therefore, how the nearly exclusive production of one hand of such molecules arose from what were presumably equal mixtures of L and D molecules in a prebiotic world has been an area of intensive research. A predominance of left- over right-handed amino acids (up to ~60%) has been found in some meteorites, but how this large amino acid asymmetry came about remains unclear. This talk will discuss the possible chemical origins of amino acids and other prebiotic organic compounds in meteorites and the implications for the origin of homochirality in life on Earth and the search for chemical evidence of life elsewhere.
Programme Leader, Medical Research Council Laboratory of Molecular Biology, Cambridge
"Origins of Life Systems Chemistry"
By reconciling previously conflicting views about the origin of life – in which one or other cellular subsystem precedes, and then ‘invents’ the others – we suggested a new modus operandi for its study. Guided by this, we uncovered a cyanosulfidic protometabolism which uses UV light and the stoichiometric reducing power of hydrogen sulfide to convert hydrogen cyanide, and a couple of other prebiotic feedstock molecules which can be derived therefrom, into nucleic acid, peptide and lipid building blocks. We are now considering the transition of systems from the inanimate to the animate state through intermediate stages of partial ‘aliveness’, and recent progress in the elaboration of building blocks into larger (oligomeric) molecules and systems in this context will also be described.
Distinguished Professor of Biogeochemistry, Director of the Alternative Earths Astrobiology Center, University of California, Riverside
Member, Virtual Planetary Laboratory, University of Washington
Honorary Professor, University of St. Andrews
"Constraining prebiotic chemistry through a better understanding of Earth’s earliest environments"
Any search for present or past life beyond Earth should consider the initial processes and related environmental controls that might have led to its start. As on Earth, such an understanding lies well beyond how simple organic molecules become the more complex biomolecules of life, because it must also include the key environmental factors that permitted, modulated, and most critically facilitated the prebiotic pathways to life’s emergence. Moreover, we ask how habitability, defined in part by the presence of liquid water, was sustained so that life could persist and evolve to the point of shaping its own environment. Researchers have successfully explored many chapters of Earth’s coevolving environments and biosphere spanning the last few billion years through lenses of sophisticated analytical and computational techniques, and the findings have profoundly impacted the search for life beyond Earth. Yet life’s very beginnings during the first hundreds of millions of years of our planet’s history remain largely unknown. This talk will center on one key point: that the earliest steps on the path to life’s emergence on Earth were tied intimately to the evolving chemical and physical conditions of our earliest environments. Yet, a rigorous interdisciplinary understanding of that relationship has not been explored adequately. Studies of the emergence of life require a mix that expands the traditional platform of prebiotic chemistry to include geochemists, atmospheric chemists, geologists and geophysicists, and planetary scientists, among others. This talk will outline the emerging targets and strategies in this pursuit, including efforts within the framework of NASA’s Prebiotic Chemistry and Early Earth Environments Research Coordination Network.