 Clinical research attempts to address a relatively straightforward, and important challenge: how do we determine whether one medical intervention is better than another, whether it offers greater clinical benefit and/or poses fewer risks? Clinicians may one day be able to answer these questions by relying on computer models, thereby avoiding reliance on clinical research and the ethical concerns it raises. Until that day, clinical researchers begin by testing potential new medical interventions in the laboratory, and often in animals. While these methods can provide valuable information and, in the case of animal research, raise important ethical issues of their own, potential new interventions eventually must be tested in human beings. Interventions which work miracles in test tubes and in mice, often leave humans untouched, or worse off.