This one had been on my reading list for a while as I was waiting for the audiobook, which is read by the author. It follows some of the interesting bits I have been seeing about the new findings in archeology that support a very different view of pre-Colombian America. Mann does a good job of synthesizing the findings, which appear only occasionally in the general media but are gaining widespread acceptance in academia.
To begin, the Americas were thickly populated when discovered. Mesoamerica has tens of millions of people. The Incas were not the only culture in South America, since even the Amazon was full of people. New England was so packed with villages that early settlers had no place to land. This matches the reports of the earliest European explorers, which had been considered unbelievable.
The Indians (for lack of a better name) invented agriculture several times, with potatoes in the Andes, corn in Mesoamerica, yams and more elsewhere in South America and a couple of different tree based societies. A remarkable achievement, since corn, yams and potatoes are indispensable to modern agriculture. By contrast, Europeans are latecomers to agriculture and owe most of their crops to other cultures.
The view that Indians lived in harmony with the land is true in general, but needs to be qualified. They modified nature to suit their purposes. To deny this is to make them simple victims of their environment and forbid them a history. They burned to keep the land free of trees so they could harvest their favorite animals. They built canals in the Amazon, islands in the swamps of Mexico, pyramids in Illinois and generally modified the landscape as humans have done everywhere they spread. Not noble savages, but merely very inventive humans facing different circumstances. After 30,000 years, there were very few "wild" landscapes they had not felt heir hands.
Why did early settlers find so few Indians, most of them wandering hunters? Europeans diseases probably killed 90-95% of them. Early explorers to the American South found the land thickly populated, with the Mississippi River crowded with villages. Within 100 years, they were all gone, destroyed by the diseases brought by those explorers. The Pilgrims settled on an abandoned village and thanked God for destroying the Indians by illness to clear a place for them. Indians were not only virgin soil for the diseases; they were also less genetically diverse than Eurasians, who had been wandering around a very large continent for far longer. If the population of Wisconsin went from 5,000,000 to about 250,000, the survivors would probably wander around in disorder too.
Not as technical or original as Jared Diamond's Guns, Germs and Steel, this is nevertheless an excellent survey for non-specialists of the current state of affairs in understanding the pre-Columbian Americas.