Yesterday evening, I finished reading The Sixth Extinction, a relatively light, rather chatty and anecdotal, but nevertheless quite interesting book by Elizabeth Kolbert. There have been five great extinctions – periods of time short by geological standards when as much as fifty or sixty or even ninety percent of all extant species of living things disappeared. Most of these extinctions were the result of gradual changes in the world’s environment – a rise or drop in temperature, for example. The last and most famous, the Late Triassic extinction that wiped out the dinosaurs and made ecological room for the expansion of the mammalian population [and eventually, for us], was the result quite literally of an event, the crashing into the earth of a five mile wide asteroid.
Kolbert’s thesis is that human beings are producing a sixth great extinction by their expansion across the planet, their rearrangement of ecological spaces [by clearing forests, building cities, and subdividing old growth areas into parcels too small to support many species, for example], and by raising the planet’s temperature so rapidly that species do not have time to adapt.
This is presented by her as a disaster, but that depends on one’s point of view. Several years ago, there were reports that the lions in Kruger National Park in South Africa were dying of pneumonia. This was widely viewed as a crisis, but it was, of course, a success story for the virus or bacterium causing the disease. E. O. Wilson likes to tell us how successful ants are as a family but not many of us have learned to adopt a formicaedean standpoint.
Anyway, the book is perfect summer reading. Enjoy.