Neoproterozoic Oxygenation Event: 100 million years of rising photosynthesis with lengthening days as Earth’s rotational speed slows, improving conditions for complex lifeĮarliest stem Cnidaria amongst the animals (early Ediacaran Period), ancestor of jellyfish and hydra: nervous system and sleep/wake cycle → without sleep we dieĮarliest bilaterian animals, with left-right symmetry ( Ediacaran Period): burrowing Ikaria with mouth and gut for scavenging, segmented Yilingia with paired legs and musculature for roamingĮxplosion in animal diversification over 20 million years (earliest Cambrian Period) emergence of modern body plans, including Deuterostomia amongst the bilaterians: tiny bag-like body with multiple openingsĮarliest chordates amongst the deuterostomes ( Early Cambrian): notochord and pharyngeal gill slitsĮarliest acute visual perception: compound and stalked eyes of stem arthropods ( Cambrian Period) → vision catalysing animal diversificationįirst colonisation of land by plants: algae of the Middle Cambrian, probably facilitated by fungi The Great Oxygenation Event: 1-10 million years of rapidly accumulating atmospheric oxygen ( Proterozoic Eon), a product of photosynthesis, and energy source for complex lifeĮarly multicellular life, with cell-to-cell signalling and coordinated responses ( Proterozoic Eon) → 37 trillion mutually-dependent cells in an adult human bodyĮarliest Eukaryotes amongst the Prokaryotes, arising from the merger of an archaeon with a bacterium: sexual reproduction with meiosis and recombination ( Proterozoic Eon)Įarliest Metazoa – animals – amongst the Eukaryotes: sponges ( Proterozoic Eon), prior to Snowball Earth episodes of worldwide glaciation
Photosynthesising bacteria amongst the Archaea ( Archean Eon), converting sunlight into chemical energy to fuel cellular activityĮarliest atmospheric oxygen, present at low levels ( Archean Eon)Įmergence of Earth’s first continents from the ocean ( Archean Eon, 3.2 to 3.3 billion years ago), supporting microbial mats in Earth’s first land ecosystem Ignition of hydrogen stars, bathing the Universe in first light of cosmic dawn → earliest galaxies of stars forming 400 million years after the Big Bang helium in stars fusing into carbon, leading to stellar nucleosynthesis of all elementsĪggregation of stars into the Milky Way galaxy: now a warped disc of 100 billion stars, one of 2 trillion galaxies in the observable UniverseĮarliest water: an interstellar vapour, and repository for oxygenįormation of the Sun and Solar System within the Milky Way, orbiting a supermassive black hole, Sagittarius A*, at its Galactic Centre every 220 million yearsįormation of the Moon from a giant impact with proto-Earthįormation of planet Earth with 510 million km² of surface area, orbiting the Sun on a yearly cycle, rotating eastward on a daily cycle around a tilted axis that perpetuates opposing polar seasonsįormation of Earth’s oceans and moist atmosphere, protected from solar wind and cosmic rays by Earth’s magnetosphere generated by its iron coreĮarliest subduction of Earth’s crust → continental plate tectonics by 3 billion years ago, unique to Earth in the Solar Systemīasaltic rock glass catalyses synthesis of RNA ( Hadean Eon): long-strand molecules carrying information across self-replicating generations and synthesising peptide proteins → pre-biotic RNA worldĮarliest life on Earth: single-celled prokaryotic Archaea ( Hadean Eon, 3.7-4.2 billion years ago), with RNA in ribosomes translating DNA in genes into proteins Discs fill with colour as time passes towards the present (further explanation below ⇓)īig Bang singularity, creation of all particles of matter and counterpart antimatter, and the laws of physics governing their interactions expansion and cooling of space → formation of the observable Universe, its galaxies, solar systems, stars, planets, moons, asteroids and comets
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