This book tells the story behind one of the most difficult--and ultimately rewarding--scientific endeavors in modern history: a multibillion-dollar international undertaking that will revolutionize our understanding of the human body. Exons, Introns, and Talking Genes is a scientist's view of the Human Genome Project. Wills explains the science as no layperson could, telling the story of the scientists involved in the project, the biomedical breakthroughs that led up to it, and how the new information it generates will change the way we understand and treat disease. Ever since Watson and Crick discovered the structure of DNA, scientists have been trying to "read" the human genetic code locked in the millions and millions of bases that make up DNA. But over the past thirty years, as many new questions have been raised as answered. Why, for example, do we carry long, repeating stretches of DNA that play no discernible role in heredity and that are currently referred to simply as "junk DNA"? Is it really true that much of human DNA is actually viral DNA-remnants, that is, of past infections? And why is most of the DNA that codes for genes quickly removed as useless "introns," leaving only the tiny but key "exons"? When completed in the next century, the Human Genome Project will have determined every gene sequence in the human body, illuminating for scientists some of the outstanding problems in human biology: the genesis of cancer, how embryos and fetuses develop, the mechanisms of aging, and the origin of mutations.