Origin of Life

Notes on how life might have emerged from non-living chemistry: definitions of life, phase transitions, and open questions still unresolved.

· Updated May 25, 2024

On this page
  • Attributes of most life forms
    • It adapts to it's environment
    • It has metabolism to keep itself going
    • Reproduction
Life

Given the incredible variety of species, definitions for life are, by necessity, very broad. But one such definition by big historian Fred Spier, is, and I quote "a regime that contains a hereditary program for defining and directing molecular mechanisms that actively extract matter and energy from the environment, with the aid of which, matter and energy are converted into building blocks for its own maintenance, and if possible, reproduction."

Earth Science

Biology

Chemistry

Physics

Questions

  • How easy or hard is it for life to emerge in situation earth was in?
    • Historically <- Assumed to be hard, very specific circumstances are required.
    • All Life we know of traces back to single ancestor.
    • Life emerged pretty quickly after water I guess. It only arose once but very early.
    • Can we recognize alt-life? not made up of cells and DNA?
  • What do we mean by life?
    • life as we know it on this planet, cellular life.
    • Some features are DNA/RNA, Proteins with same 20 L-amino acids, Genetic code, Ribosomes, Biochemistry etc.
    • A reflection of common ancestor -> LUCA(Last Universal Common Ancestor)
    • General Features
      • Growth & Development
      • Reproduce
      • Heredity of traits
      • Homeostasis
      • Metabolism
      • Cellular structure & composition
      • Respond to environment
    • Def NASA uses to lookup life -> Life is a self-sustaining chemical system capable of undergoing Darwinian evolution.
    • Self Propagation and Evolution are key
  • Phase Transitions are different from ordinary thermodynamic response.
    • Like sudden change of water to Ice, change in properties.
    • It's one way natural systems "Spontaneously form" order.
    • Order is robust due to mutual reinforcement.
  • What are order parameters for life?
    • Chemical cycles and individuality
  • Chemical Complexity
    • Nucleotide Molecule
      • Triphosphate
      • Ribose
      • Adenine <- Molecular Interactions
  • Geological Conditions, Change and Chaos
    • The Geologic Record
    • Limited direct rock data, we need complementary lab data
  • What properties and processes are easy to obtain through physical dynamics alone?
    • Reaction diffusion equations
    • Pattern Formation
  • What does the composition, structure, and function of modern life tell us about origin of life?
    • The central dogma of biology. From DNA -> Protein
    • Ribosom
    • Landauer Bound <- Efficiency
      • Life is only 20 times less efficient than physical limit, computers are 100 million times worse.
    • Similarities between different forms of life -> L-Amino Acids, D Sugars, Membranes, Proteins
    • Phylogenic Trees
  • Selection Theory