The oxygen content of earth's ocean has changed dramatically through time, beginning with essentially no oxygen and rising to present-day levels, with important consequences for the evolution of life. Oxygen levels in modern oceans are also shifting as a consequence of global warming. Learn how low-oxygen settings in the modern ocean can inform us about the "explosion" of animal life more than half a billion years ago, mass extinctions, and the future our ocean. Recorded on 3/9/2015. (#29255)