by Tim Flannery
March 6th, 2009
Subtitled "An ecological history of North America and its peoples", this book presents the story of North America's flora and fauna since the asteroid impact 65 million years ago. Although the asteroid hit the Yucutan peninsula, it was moving at a grazing angle and most of the "splash" of the impact hit North America. While the rest of the world was strangled in a kind of nuclear winter, North America was first scorched from the rain of falling superheated debris. This is why the KT boundary layer is so much thicker in North America than elsewhere: there was a thick layer of carbon from all the burned vegetation.
Flannery goes on to relate the story of how North America rebuilt its biosphere in isolation from the rest of the world, creating a biome every bit as unique as Australia's is today. However, at a later date, North America linked up with Asia over the Bering land bridge, and species began to exchange. Interestingly, lots of Eurasian species came to colonize North America, but no North American species ever colonized Eurasia -- with the notable exception of the horse. Almost all of North America's present fauna are colonists from Eurasia.
Another notable point is the extinction of megafauna about 13,000 years ago. I knew that there were extinctions at that time, but I did not realize how complete they were. Basically, almost everything bigger than a dog was wiped out. What caused this cataclysm? There are three hypotheses. The least likely is that there was a period of sudden and dramatic climate change that the big animals couldn't cope with. This hypothesis is unlikely because flora move more slowly than fauna, and so you'd expect the extinction to hit trees much harder than big animals. And that didn't happen. A second hypothesis is that there was some sort of asteroid impact at that time that was big enough to wipe out the North American megafauna but not the smaller animals, and didn't affect the megafauna anywhere else. Again, this seems far-fetched. The most popular hypothesis is that a new wave of Eurasian humans poured into the continent, possibly armed with bows and arrows, and they simply wiped out everything they could eat.
Sadly, Flannery bogs down badly when he gets to the modern era. Nearly half the book is devoted to the sad tale of how European colonists wiped out a number of species for the sheer fun of killing. Not only is the material "a real downer", but Flannery drags on and on about it. And his writing dripped with moral outrage that simply cannot be sustained over 100+ pages. Yes, we know that the white man slaughtered the passenger pigeon and the buffalo. Yes, it was really bad. But do you have do devote so many chapters to this?
With the exception of this latter part of the book, Flannery's writing is rich and lively. Time and again I shook my head while reading, thinking, "I wish I could write as well as this guy."