For August, suggested by Howard, we'll be reading 1491: New Revelations of the Americas before Columbus by Charles C Mann. Written in 2006, this book takes an in depth look at the Pre-Columbian Americas and explains how everything you learned in school is wrong. Note that this is a lengthy read so those interested in attending this discussion would be advised to start soon.
From the Amazon review:
1491 is not so much the story of a year, as of what that year stands for: the long-debated (and often-dismissed) question of what human civilization in the Americas was like before the Europeans crashed the party. The history books most Americans were (and still are) raised on describe the continents before Columbus as a vast, underused territory, sparsely populated by primitives whose cultures would inevitably bow before the advanced technologies of the Europeans. For decades, though, among the archaeologists, anthropologists, paleolinguists, and others whose discoveries Charles C. Mann brings together in 1491, different stories have been emerging. Among the revelations: the first Americans may not have come over the Bering land bridge around 12,000 B.C. but by boat along the Pacific coast 10 or even 20 thousand years earlier; the Americas were a far more urban, more populated, and more technologically advanced region than generally assumed; and the Indians, rather than living in static harmony with nature, radically engineered the landscape across the continents, to the point that even "timeless" natural features like the Amazon rainforest can be seen as products of human intervention.
Mann is well aware that much of the history he relates is necessarily speculative, the product of pot-shard interpretation and precise scientific measurements that often end up being radically revised in later decades. But the most compelling of his eye-opening revisionist stories are among the best-founded: the stories of early American-European contact. To many of those who were there, the earliest encounters felt more like a meeting of equals than one of natural domination. And those who came later and found an emptied landscape that seemed ripe for the taking, Mann argues convincingly, encountered not the natural and unchanging state of the native American, but the evidence of a sudden calamity: the ravages of what was likely the greatest epidemic in human history, the smallpox and other diseases introduced inadvertently by Europeans to a population without immunity, which swept through the Americas faster than the explorers who brought it, and left behind for their discovery a land that held only a shadow of the thriving cultures that it had sustained for centuries before.