Book excerpt: Addressing the important perspectives on xenotransplantation and human embryonic stem cell research, this book explores both the enthusiastic proponents and vehement resistance to these new biomedical technologies. Investigating the political, social, and ethical forces behind this kind of research and development, as well as the commercial actors and strong financial incentives that are necessary, these stories of hope, fear, and hype are matched by stories of success, failure, and fraud, showing how these technologies have become truly polarizing.