“Genome” is not a book about the efforts to sequence DNA. Rather, this “whistle-stop tour of some of the more interesting sites along the genome” is a book about the human condition, and the biology that underlies it. Ridley takes the common metaphor of genome-as-book more literally than most, structuring his volume in 23 chapters to mirror the 23 chromosomes in a human cell. But chromosomes are largely unorganized jumbles of often-unrelated genes, interspersed with reams of noncoding “junk” DNA (not unlike the advertising pages one has to wade through to get to the articles in a fashion magazine). The chapters of “Genome,” by contrast, each focus on clearly defined aspects of human nature and evolution–growth and development, personality and temperament, intelligence and aptitude–and a particular gene that influences each.
The most immediate benefits from genomic research will be medical, especially for diseases such as cancer, Alzheimer’s and Parkinson’s, which have resisted traditional medical approaches. “All of those illnesses have a genetic component,” says Francis Collins, who heads the U.S. government-funded sequencing effort. “Understanding hereditary contributions is going to provide the best clues we’ve ever had to what exactly is the cause.” But Ridley, emphasizing that “genes are not there to cause diseases,” looks well beyond medical applications to more fundamental aspects of what it means to be human. The result is a series of lucid essays on the biology of humanity or, says Ridley, “How we are, who we are and why we are.”
In his final two chapters, Ridley takes on two of the more troubling questions arising from genetic research: can we have free will if our genes shape our lives, and, if we know more about our genes, will we be more tempted to attempt to “perfect” humanity through eugenics? Using the example of a gene on chromosome 17 which helps control levels of the neurotransmitter serotonin (which can affect how calm or anxious a person is) in the brain, Ridley demonstrates how the action of genes can be influenced not just by the external environment but also by, for example, one’s own self-esteem. “We tend to think of genes as cause and behavior as effect,” says Ridley, “but sometimes it works the other way around.” So much for nature vs. nurture. Eugenics is more problematic, but as Ridley correctly asserts, this is more of a societal issue than a biological one. “I believe it will become a larger issue,” he says, “but I see no reason why we can’t capture the benefits of research while avoiding the pitfalls.”
By deftly blending anecdotes and case studies with clear descriptions of scientific inquiry, Ridley presents an engaging synopsis of what we know about genetics while demystifying the process by which we know it. The science is still in its infancy, and will continue to provide far more questions than answers for years to come. If scientists are able to answer even a fraction of the questions raised by new research, the sequels to “Genome” will be even more fascinating than the original.
