mspohr writes: A special issue of Science magazine devoted to 'Vanishing Fauna' publishes a series of articles about the man-caused extinction of species and the implications for ecosystems and the climate. Quoting: "During the Pleistocene epoch, only tens of thousands of years ago, our planet supported large, spectacular animals. Mammoths, terror birds, giant tortoises, and saber-toothed cats, as well as many less familiar species such as giant ground sloths (some of which reached 7 meters in height) and glyptodonts (which resembled car-sized armadillos), roamed freely. Since then, however, the number and diversity of animal species on Earth have consistently and steadily declined. Today we are left with a relatively depauperate fauna, and we continue to lose animal species to extinction rapidly. Although some debate persists, most of the evidence suggests that humans were responsible for extinction of this Pleistocene fauna, and we continue to drive animal extinctions today through the destruction of wild lands, consumption of animals as a resource or a luxury, and persecution of species we see as threats or competitors." Unfortunately, most of the detail is behind a paywall, but the summary should be enough to get the point across.