The Sixth Extinction Themes
The Sixth Extinction: An Unnatural History is the Pulitzer Prize-winning nonfiction book by journalist Elizabeth Kolbert. It examines the modern "Anthropocene extinction," the titular ongoing "sixth extinction," which is being prompted by human actions and behaviors. Thematically, the book takes an unflinching look at the various contributors to extinction events throughout the history of the earth.
The theory of catastrophism, which suggests that the earth has been shaped by violent, sudden, catastrophic events, is examined as a mechanism of extinction. This theme is investigated in chapter two, "The Mastodon's Molars," in which Kolbert concludes that the American mastodon died out as a result of a catastrophe. Their size and phenotypes otherwise supported its survival.
The Impact of Humans on Other Species
Human involvement in the reduction and extinction of species is examined through many lenses throughout the book: through the introduction of invasive species (chapter one, "The Sixth Extinction" and chapter ten, "The New Pangaea"), through the overexploitation of resources (chapter three, "The Original Penguin"), through deforestation and fossil fuel combustion (chapter five, "Welcome to the Anthropocene" and chapter six, "The Sea Around Us"), through ocean acidification due to emission intensities (chapter seven, "Dropping Acid"), through habitat fragmentation (chapter eleven, "The Rhino Gets an Ultrasound"), and through the sheer existence of human beings (chapter twelve, "The Madness Gene").
Global warming is discussed within the context of a species' ability or inability to migrate as a response to shifts in climate conditions. This is examined in chapter eight, "The Forest and the Trees," as a means of suggesting that plants and trees (which are incapable of moving) will be unable to tolerate the disruptions they are facing.
Ultimately, the book serves as a reminder to mankind of our impact and responsibility when it comes to ensuring the survival and conservation of species.