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Art Hobson, [email protected] NWA Times, 16 June 2013 A brief history of a glorious universe A contradiction stalks the modern age. If we applied our excellent brains to the humane use of modern technology, all humans could be living like kings and queens. But our culture remains mired in medieval beliefs harking back to an era when life was nasty, brutish, and short. The crying need of modern times is for our culture to get over the middle ages. Magical thinking is serving us miserably. In particular, our ignorance of planetary history is an anachronism. The universe started from a high-energy sub-microscopic quantum physics event 14 billion years ago (Bya). We have direct evidence of this big bang all around us in microwave radiation that bears its details. The first stars and galaxies formed during the first billion years. Our knowledge of how stars age informs us that our Milky Way galaxy's earliest stars developed 13 Bya. Eight billion years later, the sun and Earth were born. Here's how: A gas cloud in the Milky Way collapsed into many tens of stars, including massive stars that soon exploded and contributed their heavy chemical elements to the stillforming smaller stars. Some gases gravitated together to become our sun. Heated by infalling material, the sun eventually warmed sufficiently to ignite nuclear reactions, providing energy that then radiated through the solar system. A disk of left-over material coalesced, under gravity, into the planets. We know all this from other star-forming regions, meteorites, and computer simulations. Dating of ancient meteorites show that Earth emerged 4.6 Bya. Life was impossible in the turbulent early solar system. It is striking that, as soon as things quieted down sufficiently, life began as shown by the earliest chemical evidence 3.8 Bya and the earliest fossil evidence 3.3 Bya. Radioactive dating gives us these ages. All life on Earth is related chemically, and probably originated from a single source 3.8 Bya. The details are lost in deep time. Numerous origin-of-life experiments, beginning from such early-Earth ingredients as steam, water, carbon, and nitrogen, show that a wide variety of plausible energy sources generate amino acids and nucleic acids--the building blocks of life. Numerous scenarios show how these can form into simple biological cells. Single-cell microorganisms multiplied in the oceans for 3 billion years. Photosynthesizing bacteria evolved, supplying oxygen (a byproduct of photosynthesis) to the atmosphere. Complex "eukaryotic" cells appeared 2 Bya, making sexual reproduction possible. This increased the evolution rate, resulting in the first multicellular organisms. Atmospheric oxygen accumulation allowed formation of the ozone layer (ozone is a form of oxygen), which shielded the planet from the sun's high-energy radiation, allowing complex life to survive on land. Organisms proliferated in a creative burst called the Cambrian explosion during 580-500 million years ago (Mya). The rate of evolution increased by a factor of ten, the diversity of life began to resemble that of today, and life moved onto land. Higher oxygen levels permitted large, active animals. Animals with vertebrae evolved. Dinosaurs and mammals appeared at about the same time, 225 Mya. A comet or asteroid impact in the Gulf of Mexico 66 Mya made nearly all dinosaurs extinct. Only a few bird dinosaur bird species, the source of all of today's birds, survived. Mammals suffered losses, but many survived and then diversified. The first primates, tree-living animals including lemurs and monkeys, evolved 75 Mya. Apes diverged (formed a separate evolutionary line) from the monkeys 25 Mya. 6 Mya, a new type of ape evolved, one that came down from the trees to stand erect on two feet. These are called "hominids," meaning any species on our side of the ape-human divergence. There have been over 20 separate hominid species. All stood on two feet. These include genus Sahelanthropus evolving 6 Mya, genus Ardipithecus 4.4 Mya, 8 species of genus Australopithecus during 4.2-2.1 Mya, and at least 9 species of the genus Homo, including Homo habilis 2.4 Mya, Homo erectus 1.8 Mya, archaic Homo sapiens 0.5 Mya, Homo sapiens neanderthalensis 0.23 Mya, and modern Homo sapiens evolving 0.20 Mya (200,000 years ago)--the only hominid left standing today. Nine of these hominid species survived far longer than we have so far. This history has an unmatched grandeur. It's time to bring education into the modern age, and to begin to understand who we are. We have a far deeper natural inheritance, and inhabit a far more majestic universe, than we could possibly have imagined. Standard history courses extend to the ten thousand years since the agricultural revolution; this represents only an instant of our true heritage.