Earth coalesced from molten, interstellar debris about 4.6 billion years ago. Within 1 billion years, its crust had cooled into a puzzle of tectonic plates, a mosaic of continents and oceans covered its surface and life had appeared in its primordial seas. It would be another 3.2 billion years before primitive plants and animals colonized the land and almost 3.6 billion years before the first humans gazed upon their home planet.
Throughout that long history of evolution, the tectonic plates have been in constant motion, spreading apart, subducting, colliding and scraping against one another. In concert, oceans have opened and closed, continents have merged and rifted apart and the planet has witnessed an endless chain of tectonic activity, producing volcanism, earthquakes, tsunamis and climate change. All of these events have had an impact on Earth's landscape and on the life forms that inhabit this planet, including humans. Indeed, our species was nearly obliterated by the eruption of the Toba supervolcano, on Sumatra, 74 thousand years ago.
Contrary to the views instilled by various religions, the Earth was not created in preparation for human occupation. We, like other species, evolved in concert with our planet and this evolutionary process, governed by tectonic forces and natural selection, continues today. The log of recent earthquakes, tsunamis and volcanic eruptions clarifies this point and warns us that natural cataclysms, whether along the San Andrea Fault, at Yellowstone or via a wayward meteor, will continue to mold the future of both our planet and our species.
