How did we get from the Big Bang to today's staggering complexity, in which seven billion humans are connected into networks powerful enough to transform the planet? And why, in comparison, are our closest primate relatives reduced to near-extinction? Big History creator David Christian gives the answers in a mind-expanding cosmological detective story told on the grandest possible scale. He traces how, during eight key thresholds, the right conditions have allowed new forms of complexity to arise, from stars to galaxies, Earth to homo sapiens, agriculture to fossil fuels. This last mega-innovation gave us an energy bonanza that brought huge benefits to mankind, yet also threatens to shake apart everything we have created.