When students of the future memorize the touchstone dates of scientific discovery, they are likely to rank the year 2000 along with 1859, the year Charles Darwin published The Origin of Species. The beginning of the millennium will stand out because a new biological milestone is imminent - the decoding of the human genome.

Matt Ridley's Genome: The Autobiography of a Species in 23 Chapters is an earnest appraisal of the implications of this mighty endeavor. In both style and content, the book recalls classic reports by war correspondents or adventurous journalists accompanying explorers into unexplored regions. For Ridley, the unlocking of the genetic code is a transforming event like a decisive battle or other standout moment in history. Humankind is not going to be the same.

The author's zeal is not misplaced. His perceptive, often witty account of humanity's "autobiography" vigorously espouses the importance of genetic research. Ridley, however, does not describe the institutional history of the Human Genome Project, which is leading the government's effort to describe every human gene. Rather, he focuses on the likely consequences of the research as well as on the "causes" that can be traced to the project's results.

The use of "causes" here has nothing to do with causality and everything to do with contention. Genetic research, particularly since the rise of the biotechnology industry, has become one of the most controversial fields in all of science.

The work of the Human Genome Project is adding new fuel to the flames. The deciphering of the genetic code raises both expectations of cures for long-standing illnesses and parallel fears of creating new, unimaginable diseases. Ethical considerations are raised over the right of "ownership" of an individual's genetic information. Fears of new Nazi-like experiments are being voiced. These fears go so far as to include "perverted science" that raises the threat of societies composed of genetically programmed humans rather than beings of free will.

Faced with a vast and divisive subject, Ridley organizes his narrative in an unusual and effective manner. Each of his chapters is matched with one of the twenty-three pairs of chromosomes on which the human genome is stored in a chemical code consisting of three-letter "words" spelled with the DNA alphabet - A, C, G, and T.

With 8,000 currently identified genes (of an estimated 80,000) to choose from, Ridley made the wise decision to emphasize one gene of particular importance in each chapter. He notes that his selections are "emblematic" of the whole genome, salient points in the expanse of human evolution.

Chapter 1 considers the symbiotic relationship of DNA and RNA and the origins of life. The author focuses on a short filament located on chromosome 1. Here a small gene, a 120-letter sequence known as 5s RNA, is copied and recopied. This is part of the crucial chemical process whereby the genetic information of our DNA is replicated. It is essential to all living things and hearkens back to the first stirrings of life on earth. "This short paragraph," Ridley writes, "is perhaps as close as we can get to an echo of the original word."

Ridley's treatment of the DNA and RNA connection conveys the essence of his literary style. It is both evocative and incisive. He writes in a manner that the general reader can readily understand, yet the science enthusiast will appreciate the power of his prose.

In later chapters, however, Ridley encounters a recurrent problem: How to treat genetic disease. At several points in his narrative, he writes in boldface print, "genes are not there to cause disease." Yet the human genome is partly the end product of our species' responses to the maladies that assail us.

Genetic change, for instance, produced the sickle-cell mutation in people of West African descent, a mutation that enables them to resist malaria. Unfortunately, those with two copies of this gene frequently die from the sickling and collapse of their red-blood cells, which clog their blood vessels, depriving their cells of oxygen.

"Sickle-cell disease is a high price paid today for malaria resistance in the past," Ridley writes. Moreover, genetic resistance to other diseases also comes at a price. People with heightened genetic resistance to tuberculosis, for example, are susceptible to osteoporosis. And those with genetic resistance to typhoid are susceptible to cystic fibrosis.

It is particularly chilling that the genetic alterations leading to many dread genetic diseases are seemingly slight and usually impossible to cure. Huntington's chorea is a good example. On chromosome 4 can be found the genetic word CAG, standing for the amino acid glutamine. As Ridley notes, in most people CAG is repeated 10 to 15 times. A person with 35 repetitions will successfully evade Huntington's, but a person with just four more is doomed to suffer the devastating neurological breakdown produced by this inherited condition.

Given the complexity and delicacy of our genetic makeup, it is understandable that fears have arisen about tampering with the basic structure of life. Ridley, however, is a resolute opponent of those who seek to limit genetic research and its applications in agriculture and medicine. He persuasively argues that the application of our knowledge of the genome will lead to enhanced nutrition and to forms of health care adapted to the treatment of each individual's genes.

Ridley also maintains that the "Frankenstein" scenario has more frequently been exemplified by governmental policies that target nurture, rather than by experiments with nature. Ranging from behavior modification to the eugenics crusade, attempts to create "superior" citizens reflect political repression in pseudoscientific guise.

Exactly the opposite is true of genetic science. "Again and again the genome drives home the lesson of our individuality," Ridley declares. "The diversity of humanity is its greatest message."

Matt Ridley's Genome is a tract for our times, offering insight on scientific discoveries of momentous importance. It is also an essay on the nature of human freedom. Far from being slaves to our genes or prisoners of our upbringing, we are the unique end product of both. There are many lessons in this memorable book to ponder. But this one in particular is of transcendent significance. Our unique genetic and social heritage is quite literally our birthright.