One of the most critical and relevant areas of scientific inquiry in our time has been aimed at understanding how and why the Earth came to be a hospitable abode for life, while the other rocky planets, even Earth’s near twin Venus, did not. One of the most critical forces may have been life itself. The appearance of plants, for example, was responsible for contributing substantial amounts of oxygen—the sine qua non for life—to Earth’s original heavily carbon dioxide­based atmosphere. Carbon dioxide, which dominates Venus’s atmosphere, is in large part responsible for that planet’s hostile temperatures.
