Do you want to be a doctor or a scientist? Yes, there is a difference. Medical doctors are trained to make patients feel better, and the best way to do this, generations of medical educators have judged, is to provide M.D.s with the practical skills and knowledge needed to diagnose and treat common ailments. M.D.s are the engineers of medical science.

Scientists, on the other hand, are often masters of detail, captivated by minute aspects of their chosen disciplines. Basic scientists are motivated by a desire to understand underlying mechanisms, to discover things that no one else knows. There is, often as not, another motivation: Many basic scientists hope that eventually their discoveries may make the world a better place. Eventually.

There have always been people who wanted to do both: make people feel better, and understand, at a fundamental level, the functions and malfunctions of the human body, and many of them have chosen to become physician-scientists. These physician-scientists have been uniquely successful at addressing the underlying science of human health and disease, often transforming that knowledge into practical treatments for human ailments.

Enter the M.D./Ph.D. track. Today, some 90 M.D./Ph.D. programs exist in the United States alone, and there are several more in Canada. These programs offer many advantages, not the least of which are generous scholarships, and those who participate often go on to very rewarding careers. But it's a long road, little known and poorly lit. Enter Science Careers, bearing a torch to light the way.

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Jim Austin is the editor of Science Careers. @SciCareerEditor on Twitter

Rod Ulane is Associate Dean for Graduate Biomedical Education at the New York University School of Medicine.