In humanity's more than 100,000 year history, we have evolved from vulnerable creatures clawing sustenance from Earth to a sophisticated global society manipulating every inch of it. In short, we have become the dominant animal. Why, then, are we creating a world that threatens our own species? What can we do to change the current trajectory toward more climate change, increased famine, and epidemic disease?

Renowned Stanford scientists Paul R. Ehrlich and Anne H. Ehrlich believe that intelligently addressing those questions depends on a clear understanding of how we evolved and how and why we're changing the planet in ways that darken our descendants' future. The Dominant Animal arms readers with that knowledge, tracing the interplay between environmental change and genetic and cultural evolution since the dawn of humanity. In lucid and engaging prose, they describe how Homo sapiens adapted to their surroundings, eventually developing the vibrant cultures, vast scientific knowledge, and technological wizardry we know today.

But the Ehrlichs also explore the flip side of this triumphant story of innovation and conquest. As we clear forests to raise crops and build cities, lace the continents with highways, and create chemicals never before seen in nature, we may be undermining our own supremacy. The threats of environmental damage are clear from the daily headlines, but the outcome is far from destined. Humanity can again adapt: if we learn from our evolutionary past.

Those lessons are crystallized in The Dominant Animal. Tackling the fundamental challenge of the human predicament, Paul and Anne Ehrlich offer a vivid and unique exploration of our origins, our evolution, and our future.

"Since the 1968 publication of Paul and Anne Ehrlich's The Population Bomb, they have played a major role in generating awareness of looming ecological crisis. While their more dire predictions (millions dead in famines before the end of the 20th century) have not come to pass, the correctness of their fundamental thesis-that we are in danger of undermining 'the ability of Earth's environment to support much of life-including our own,' is now widely accepted. Forty years later, they consider scientific, technical and cultural developments (especially in the fields of genetics and information technology), and how they've raised the stakes, perhaps 'putting all of humanity on a course resembling the fate of ancient civilizations that collapsed.' They argue clearly and convincingly the pressing need for a global shift away from the ever-expanding siren call of consumerism, the culpability of corporate interests that have promoted resource-draining suburban sprawl, and the self-serving wastefulness of 'the most affluent fifth of the U.S. population.' Tough hopeful that such widespread transformation is possible, the Ehrlichs contend that it's only the encroaching crisis that will inspire it — unless, that is, this fascinating, inspiring book gets the wide audience it deserves." Publishers Weekly (Copyright Reed Business Information, Inc.)

Canadians joke that, given their vile winters, they are the only people in the world who welcome global warming. But some things are too serious for humor. The world is in a crisis because of rising temperatures. Climate patterns have been disrupted, with devastating effects on lands near and far. Regions that once produced food in abundance are now arid deserts. Australians, for instance, are starting... Washington Post Book Review (read the entire Washington Post review) to realize that their steady succession of droughts may not be a statistical blip but something more serious and permanent. The polar regions north and south are melting and breaking up, leading not just to short-term effects for animals but also to fears of rising ocean levels and the consequent flooding of today's dry land. Miami could find itself the Venice of the future, a city surrounded by waters.

No one has more authority to write on these matters than the husband-and-wife team of Stanford biologists Paul and Anne Ehrlich. For decades now they have been documenting and warning of humans' effects on the environment. Their new book, "The Dominant Animal," continues their chronicle of the damage we have done to our home. And although they write in prose of a high quality that is rare among academics, let alone scientists, gloomy reading is what they offer. But they want to do more than simply wail, Cassandra-like. They also want to dig into how and why we got into the predicament in which we find ourselves.

For the Ehrlichs, human evolution is the cause of our technological triumphs and tragedies. They emphasize that it is a mistake to think, however, that the causes of such evolution can be reduced simplistically to single factors. We must take into account both genetics and culture. The underlying foundation of human thought and behavior may be innate and rooted in our DNA, but the peculiar thing about Homo sapiens is how we lay culture and learning on top of all our biology. A prime example is controlling population growth. As the Ehrlichs point out, from an evolutionary perspective, nothing is more important than having babies. Until fairly recently, human numbers were kept in check by the natural misfortunes that befall almost all animals and plants, such as diseases, predators and food failures. But, thanks to culture, especially in the 20th century, human population exploded: A billion people were added in the two decades from 1950 to 1970. This was a direct function of technological advances, especially pesticides (leading to larger harvests) and antibiotics (leading to fewer deaths from disease).

These huge increases put pressures on people to produce even greater amounts of food, more housing and everything else needed for living. The most rational thing would be for us to notice that life has changed and to restrict our family sizes. But it isn't that simple. The Ehrlichs stress that human evolution at the cultural level is "sticky." We don't just change behaviors, throwing over beliefs, because circumstances are different. Patterns of behavior and thought get engrained and are hard to modify, and there are good biological reasons for this. If something works well over the course of time, then it makes sense that it should be protected against change: Stay with the tried and trusted because on average this will pay off the biggest dividends.

This stickiness has clearly contributed to our ecological crisis. Cultural patterns in such areas as agriculture have led to the great success of humankind, but these same patterns are leading us to strip rain forests and pump out greenhouse gases, leading to today's mess. Getting an understanding of how the interactions of biology and culture affect human behavior is itself reason to read this book.

I wish, however, that the Ehrlichs had made more of their profound insights. The last part of "The Dominant Animal" addresses how we might improve our position, for instance, by eschewing fossil fuels and relying much more on renewable sources of energy. But there is not enough about how we are to overcome our sticky cultural assumptions and do what is in our long-term interest. Houston, for example, recycles less than 3 percent of its waste, whereas San Francisco recycles nearly 70 percent. This is not because the people of Houston are less evolved than the people of San Francisco, but because the infrastructure and incentives are just not there. We need to be discussing how our inclinations to choose the quick and easy fix can be replaced by other cultural imperatives. In wartime, for instance, people can be persuaded to make sacrifices for the sake of the nation. Should we be thinking about a war on environmental destruction?

This is an important book, with much information and some really stimulating ideas. We need to build on these ideas, because the world is in an environmental mess and things are not getting better.

Reviewed by Michael Ruse, co-editor of the forthcoming 'Evolution: The First Four Billion Years', Washington Post Book World (Copyright 2006 Washington Post Book World Service/Washington Post Writers Group)
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