He reviews a number of controversial test cases. Was the extinction of many large animals in North America's fabulous bestiary due to over- hunting by Indians' remotest ancestors, "mythical Pleistocene hit men", as one Indian writer sarcastically called them in rejecting this theory? Did the Hohokum people of Arizona engineer their own annihilation by building the continent's most extensive canal system, and then fill it with water too saline for their crops? Were deliberate fires, employed by many Indians for hunting, clearing ground, communicating and waging war, used with a true "ecological" understanding of the consequences? Were Indians who trapped beaver to just short of extinction driven to abandon traditional conservation by the need to trade with Europeans and a lethal thirst for their brandy? And are Native Americans today as ecologically sound as their ancestors?
In each case, Krech rejects explanations with a single cause, showing the interplay between the many Indian peoples and their many environments was always subject to changing pressures. In some cases, he refuses to reach a conclusion, insisting the historical record is insufficient for any theory. Again and again, he demonstrates the need to check fashionable generalisations against specific instances.
The Ecological Indian would seem to have been exemplified by the Plains Indians, who were dependent on the buffalo. Their understanding of ecological balance is often contrasted with the gross destructiveness of white hunters who brought the national herd (of, perhaps, 30 million) to the brink of extinction in the 1870s. But Krech suggests the buffalo was in difficulty already due to disease, drought and competition for grazing from the Indians' own ponies. And, he hints that by the 19th century, Indian demands alone were perhaps becoming unsustainable by the buffalo population.
He goes on to show that Indians used methods of hunting that could be horrifically wasteful, as when they drove buffalo over cliffs and butchered only the topmost layer of crippled animals. But, in a frustratingly brief passage, he puts this in a cultural context. Such slaughters were ecologically justified, in the sense that the Indians believed any escaping buffalo would warn others to stay away in future. They also believed buffalo emerged each spring in "countless throngs" from caves, having passed the winter on prairies beneath the lakes.
The religious relationship between the Plains Indians and the buffalo was carefully managed through ritual. Thus they can be called conservationists only if it is accepted that they were at greater pains to conserve their spiritual kinship with the buffalo than any actual herd. The "Ecological Indian" is not a credible figure unless his own, essentially religious, concept of ecology is taken into account.
Bringing this humane and judicious survey to a close, Krech reports that not all today's Indians can afford to be environmentally progressive. Driven by the need for revenue and employment, some tribes have allowed reservations to be used for dumping trash and even nuclear waste. But, the beaver owes its present healthy state to the discipline of its Indian hunters, whose ancestors prior to the 19th century had no interest in what we would recognise as conservation.
Despite the vigorous revival of traditional religions, there are Native Americans who are suspicious of the "Ecological Indian", arguing that it is only another patronising image to keep Indians locked up in the past. If that has been the effect of the myth, then Krech's respectful revisionism should counteract it. Perhaps the sagest judgement on the debate came from a contemporary Choctaw. "Just because I don't want to be a white man," he said, "doesn't mean I want to be some kind of mystical Indian either. Just a real human being."