The book begins near the beginning of evolution - when amphibians started to begin forming. Frogs, which are the most common type of amphibian, had ancestors dating back to 400 million years. These little creatures have persisted for longer than the dinosaurs, yet today, their numbers are dwindling. A particular example noted in the book is that of a species of frog native to Panama. These frogs are now dying because of a fungus not native to the region, which could only have been brought their by the extensive networks of humanity's interregional trade.
The book continues to discuss some previous extinctions, such as the mastodon. George Cuvier believed that these large mammals had to have died from some sort of catastrophe, as they were naturally adept and fit to survive natural circumstances. Therefore, something truly fast and tragic had to have happened to kill them out.
Finally, we approach the modern day and the devastating effects of the Industrial Revolution. Since the 1800's, water and carbon dioxide levels have been rising, which has led to the extinction of many animals prone to pollution. Furthermore, interregional trade has quickly spread diseases and invasive species to new parts of the world, much like when Europeans brought diseases like smallpox to the Americas for the first time.
