Each bead in this orange string represents one hundred million years, from the creation of the sun to the present. Descriptions are taken from the short version of the Great Story Timeline. Note that some of the beads are identical to those on the billions string that represent the same event.
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| 50 hundred million years ago (hmya) - A SHOCK WAVE from a nearby supernova explosion energizes the primordial cloud of hydrogen gas, now enriched with complex atoms, that will become our swirling solar system. Our SUN IGNITES. |
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| 46 hmya - EARTH and other planets in our solar system form by aggregating space debris in their orbital paths. Meteors and comets that crash into Earth become Earth. |
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| 45 hmya - The MOON is carved out of Earth by a huge meteor impact; its orbit around Earth gradually becomes more distant through time. |
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| 41 hmya - The Great Bombardment of meteors ends; Earth begins to cool and water vapor in the atmosphere falls as RAIN for the first time. OCEANS form. Let there be rain! |
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| 38 hmya - The first LIFE forms (Archaea, a heat-loving form of bacteria) evolve in a very hot environment, possibly at great depth within Earth's crust or at hydrothermal fissures in the floor of oceans. |
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| 32 hmya - Water-based PHOTOSYNTHESIS is invented by blue-green cyanobacteria to cope with a shortage of hydrogen atoms, previously scavenged from volcanic gases: pure hydrogen and hydrogen sulfide. The energy in sunlight is used to break apart water (H2O) molecules, thus opening up a virtually unlimited supply of hydrogen atoms. The amount of life on Earth (biomass) increases as a result. |
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| 28 hmya - Closed-cycle metabolisms of GAIA are now fully in place. Life mediates crucial links in the biogeochemical cycles of carbon, nitrogen, and oxygen, thereby maintaining an endless re-supply of Earth's finite reserves of elements vital for life. One form of life's waste is another's food. Several billion years later, humans will realize that they too must RECYCLE fully in order for their cultures to remain sustainable. (This fourfold Celtic knot represents to me the four interconnected systems of Gaia: lithosphere, hydrosphere, atmosphere, and biosphere.) |
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| 20 hmya - EUKARYA arise via symbiogenesis (in response to Oxygen Crisis and possibly a shortage of phosphorus?). Life becomes nested - one center of creativity within another, as oxygen-using mitochondria and photosynthesizing plastids cooperate with the larger host cells. Single-cell "protozoa" (protists) emerge. This bead looks to me like a protozoan as seen through a microscope. |
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| 15 hmya - MEIOTIC SEX emerges in eukarya, which is the first step in what will eventually evolve into a mode of reproduction that entails egg and sperm. Genetic exchange and reproduction are now linked into a single process. |
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| 10 hmya - Single-celled creatures invent PREDATION by developing flexible amoeba-like pseudopods that can surround a "prey" and secrete enzymes into that enclosed space (vacuole). (I know a ladybug is a far cry from a single-celled amoeba, but it is at least a fierce predator!) |
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| 5.6 hmya - The first multicellular life forms in the sea evolve distinctive body forms. MULTICELLULARITY is an innovation in which the offspring of dividing cells stay in bonded association with one another, resulting in synergies of community. |
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| 5.4 hmya - SIGHT is invented, and is most sophisticated in the compound eyes of trilobite arthropods, the lenses of which are transparent crystals of calcite. Earth begins to see! Sight will be invented afresh well more than a dozen times by different lineages of life. |
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| 4.4 hmya - A freshwater green alga and aquatic fungus pool their talents (symbiosis), merging into the first LAND PLANTS. Life thus embarks on the adventure of weather and gravity. The continents grow green with low-lying ancestors of today's MOSSES and liverworts, which lack roots, and so must go dormant in dry conditions. |
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| 2.9 hmya - PANGAEA forms, a single supercontinent. (This bead is green on one side, blue on the other.) |
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| 2.1 hmya - DINOSAURS, which originated in the Triassic, become the largest land animals of all time, in the form of the great herbivorous sauropods (e.g. Brachiosaurus, Diplodocus), which reach their zenith in size and diversity during the Jurassic. LARGE MARINE REPTILES (the snakenecked PLESIOSAURS and dolphinlike ICHTHYOSAURS) arise, as do the flying PTEROSAURS. (This bead is actually a crocodile; its belly is shown here.) |
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| 1.4 hmya - Early MAMMALS diversify, but have little ecological presence and get no bigger than squirrel-size. (This bead is a hedgehog.) |
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