Quammen investigates the fascinating relationship between humans and what he calls "alpha predators": animals that hunt, kill, and eat humans. Likewise, he analyzes how humans, in turn, have revered, hunted, captured, and killed fascinating "man-eaters" throughout the centuries.

He explores "why big, fierce animals are rare."

Large, predatory animals, like tigers, lions, bears, sharks, and crocodiles, have brought both intrigue and fear to humans since their existence.

Among the earliest forms of human self-awareness was the awareness of being meat.

From his travels around the world, he shares insights into the coexistence of humans and animals in particular areas. One group of people he studied were the Malhardis, herders who live outside Bombay.

Life, as they choose to live it, is hard and elemental. It's harder still for their animals. A milk cow is no challenge to a hungry lion but, defended by a herder with the light tool known as a kuwadi that is commonly carried, the cow has at least a chance of escape.

Insofar as it's possible to make a categorical statement about the private lives of an extraordinary, little-studied group of people, here's one: Maldharis don't own guns. Their battles with the lions approximate hand-to-hand combat, not safari hunting or varmint eradication. Their chief weapon, the kuwadi, is barely more than a short-handled hoe. Their relationship to Panthera leo persica is wary but intimate. Rarely does a herder get hurt. Part of being a Maldhari, at least at Gir, is coping routinely with lions through the use of caution, bluff and an occasional kuwadi-thunk on the skull.

Quammen asserts that the socioeconomic status of a group of people can also affect its interactions with alpha predatory animals. He basically claims that the rich have a better chance to kill the animals, and the poor have a higher chance of being killed by the animals.

It's a general truth . . . sometimes noted but seldom quantified or analyzed: predation is costly and the costs are unevenly distributed. Large predators cause more material loss, inconvenience, terror, suffering and death among poor people (specifically poor people who live in rural circumstances within or adjacent to the habitat) and among native people adhering to traditional lifestyles on the landscape . . . than to anyone else. Proximity plus vulnerability equals jeopardy.

Quammen also studies how alpha predators hold an influential, sometimes spiritual, position in many native lands. The effect of killing such animals can be great, in many senses, for the people of the land.

Kill off the sacred bear. Kill off the ancestral crocodile. Kill off the myth-wrapped tiger. Kill off the lion. You haven't conquered a people, or their place, until you've exterminated their resident monsters.

Claiming that many intriguing alpha predators will be eliminated from the earth by either destruction of their habitat or hunting, Quammen predicts that many of these animals will no longer exist by 2150.

He warns that killing off these ''keystone species'' will affect the ecosystem as well as humans' dwelling on the earth. While humans have the power to wipe out many animal species, Quammen argues that this power is detrimental to all of life.

Nor are we the culmination of evolution, except in the sense that there has never been another species so bizarrely ingenious that it could create both iambic pentameter and plutonium.