I recently finished The Sixth Extinction, a Pulitzer-Prize winning book by Elizabeth Kolbert. Over the last half-billion years, there have been five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Kolbert posits that we are currently experiencing the planet’s sixth extinction. This time around, however, the cataclysm is not an asteroid or a natural event—but us. For the last thousands of years, at an accelerating pace, human existence has drastically been altering the environment.