That way the student can use the lecture to gain insight into difficult material rather than spending the lecture hectically transcribing the lecturer’s comments onto the notebook page. The latter is best accomplished if the student reads the appropriate text chapter before coming to lecture rather than after. In this text, we stress critical thinking, an approach that emphasizes understanding over memorization, experimental proof over the pronouncements of authorities, problem solving over passive reading, and active participation in lectures. We provide solved problems at the end of each chapter to help. After the student has worked out the problems, he or she can refer to the answer section in Appendix A. All problems within the body of the text and a selection at the end of the chapters should be worked through as they are encountered. This text provides a larger number of problems to help the student learn and retain the material. There is no substitute for work with pad and pencil. Because genetics is the first analytical biology course for many students, some may have difficulty with its quantitative aspects. Throughout this text, we examine the implications for human health and welfare of the research conducted in universities and research laboratories around the world boxed material in the text gives insight into genetic techniques, controversies, and breakthroughs. Genetic controversies-such as the pros and cons of the Human Genome Project, the potential ethical and medical risks of recombinant DNA and cloning of mammals, and human behavioral genetic issues such as the degree of inheritance of homosexuality, alcoholism, and intelligence-have captured the interest of the general public. An understanding of genetics is crucial to advancements in medicine, agriculture, and many industries. A comprehensive glossary and index will help maintain continuity if the instructor chooses to change the order of the chapters from the original. For this reason, the chapters have been grouped as units that allow for flexibility Other teachers, however, may prefer to begin with molecular genetics. Many genetics teachers feel that a historical approach provides a sound introduction to the field and that a thorough grounding in Mendelian genetics is necessary for an understanding of molecular and population genetics-an approach this text follows. Genetics is commonly divided into three areas: classical, molecular, and population, although molecular advancements have blurred these distinctions. For an understanding of the concepts in this text, however, the motivated student will need to have completed only an introductory biology course and have had some chemistry and algebra in high school. Most readers of this text will have taken a general biology course and will have had some background in cell biology and organic chemistry. This text provides a balanced treatment of the major areas of genetics in order to prepare the student for upper-level courses and to help share in the excitement of research. Genetic concepts provide the framework for the study of modern biology. No area of biology can truly be appreciated or understood without an understanding of genetics because genes not only control cellular processes, they also determine the course of evolution. The science of genetics includes the rules of inheritance in cells, individuals, and populations and the molecular mechanisms by which genes control the growth, development, and appearance of an organism. Some students will contribute to the answers. What lies in the future? What will the twenty-first century, the century of genomics, bring? Will geneticists a hundred years from now speak of a complete cure for cancer, heart disease, and mental illness? Will we have a cure for autoimmune diseases such as diabetes and arthritis? Will aging be slowed or even prevented? Will we have a complete understanding of the process of development and a concurrent elimination of birth defects and developmental problems? Will genetics put an end to world hunger? How will we live, and what will be the quality of our lives? The students who now are taking genetics will learn the answers to these questions as time progresses. PREFACE he twentieth century began with the rediscovery of Mendel’s rules of inheritance and ended with the complete sequence of the human genome, one of the most monumental scientific accomplishments of all time. Tamarin: Principles of Genetics, Seventh Edition