essentially inedible precursors such as teosinte was significant because it enabled the production of crop surpluses, growing populations and complex cultures, and was pivotal to the rise of civilizations such as the Olmec. Mann notes that Mesoamericans did not have the luxury of "stealing" or adopting inventions from others, since they were geographically isolated in comparison to the cultures of Eurasia. There a large, relatively open landmass had resulted in extensive trading and warfare, both of which dispersed cultural inventions. In the Americas, cultures were somewhat more isolated. They did not invent the wheel and mostly lacked domesticated large animals. Part Three: Landscape With Figures In the third section, Mann attempts a synthesis. He focuses on the Maya, whose population growth appears to have been as rapid as its decline. The canonical theory about the disappearance of Mayan civilization, a pattern common among many Native American cultures, was stated by Sylvanus Morley as: "the Maya collapsed because they overshot the carrying capacity of their environment. They exhausted their resource base, began to die of starvation and thirst, and fled their cities 'en masse', leaving them as silent warnings of the perils of ecological hubris." Mann discusses the growing evidence that shows Native Americans did transform their lands. Most Native Americans shaped their environment with fire, using slash-and-burn techniques to create grasslands for cultivation and to encourage the abundance of game animals. Native Americans domesticated fewer animals and cultivated plant life differently from their European counterparts, but did so quite intensively. Ancient cultures in South America have been found to have constructed elaborate irrigation systems and terraced steep mountains to produce crops and defensively protected settlements. The author suggests that Europeans' limited and often racist views about the indigenous peoples, in addition to lack of a common language among the indigenous peoples, often resulted in a failure by Europeans to recognize how Native Americans managed their lands. Some historians drew conclusions such as the "law of environmental limitation of culture" (Betty J. Meggers); that is, Native Americans practices before slash and burn worked because vast expanses of healthy forest appeared to have existed before Europeans arrived. Mann argues that, in fact, Native Americans were a keystone species, one that "affects the survival and abundance of many other species". By the time the Europeans arrived in number to supplant the indigenous population in the Americas, the previous dominant people had been almost