Continent that grew on blood, bones and shadows of forgotten souls

Despite the best efforts of archaeologists and other scholars, the popular image of the Americas before 1492 remains little more than a pastiche of Native American tribes wandering across a virgin continent. Charles Mann's Ancient Americans is a timely reminder that the history of the Western hemisphere did not begin with Columbus and Cortés but at least 15,000 years earlier.

Mann wisely elected not to write a systematic account of cultural and social development before 1492 or an intellectual history of the new perspectives shared by scholars involved in ancient America. Instead, he focuses on three major issues: Native American demography, the perennial mystery of the first Americans and Native American ecology. All three are enormous subjects in their own right, and Mann admits that he has been selective in his choice of cultures and peoples, using either what he calls the "most intriguing" or those that are among the best documented. He uses a classic journalistic approach - a meld of interviews and personal experience with wide reading in the complex and often confusing academic literatures of numerous disciplines. The result is an intriguing synthesis of hard data and personal perceptions that gives the reader an entertaining impression of the many controversies and uncertainties surrounding all three of his chosen issues.

No one denies that European diseases such as measles and smallpox took a terrible, if unintended, toll of Native Americans. Generations of demographers have tried to calculate how many people lived in the New World in 1491. Conservative estimates are as low as a few million, the most generous are as high as 112 million. The subject has become a politically loaded issue, with higher numbers now in fashion.

Mann takes us on an open-ended journey through the controversies but is clearly in favour of a higher number, referring back to the 16th-century Dominican friar Bartolomé de las Casas, who estimated that 40 million Native Americans perished in the half century after Columbus landed in the Indies.

In part two, "Very old bones", Mann devotes a chapter to a survey of the perennial debates over the first Americans, where he explores familiar arguments over pre-Clovis and Clovis, and devotes space to the current debates over coastal routes and DNA.

I particularly enjoyed the next chapter where the author skilfully mingles a discussion of the importance of fishing and cotton to the development of civilisation on the Peruvian coast with a dissertation on tortilla-making and the history of maize from its origins in a wild grass, teosinte. He then takes us on a brief journey through Olmec society and through Maya writing and calendars, before returning to the Andes to the little-known highland polities of Wari and Tiwanaku. Here he confronts us with the reality that modern-day observers can never hope to understand the intricacies of the ancient cosmos.

"Landscape with figures" examines the ecology of ancient America, starting with the Maya collapse of the 10th century AD that has become somewhat of an ecological cautionary tale for green activists. The same folk also frequently assume that Native American societies lived in spiritual balance with the environment. Mann points out that Native American interactions with the environment were as diverse as their many societies.

Native Americans did not live lightly on the land and often cultivated it on a large scale. He cites the example of Cahokia in the Mississippi Valley, where a crisis of legitimacy erupted 900 years ago, and takes us to the Maya heartland with its great cities, where leaders failed to find political solutions to ecological problems. Most important, he takes us to Amazonia, a historically much neglected part of the continent, where he argues from new perceptions of the environment that the Native Americans were an essential component in the formation of the present-day rainforest.

He dismisses any notions of an environmental utopia. "Native Americans ran the continent as they saw fit. Modern nations must do the same. If they want to return as much of the landscape as possible to its state in 1491, they will have to create the world's largest gardens."

Ancient Americans is historical and scientific journalism at its best, a beautifully written and provocative introduction to the New World before Columbus.

Brian Fagan is emeritus professor of anthropology, University of California, Santa Barbara, US, and the author of many general books on history and archaeology.