But aside from these determinants, one factor stands out which may not always be obvious because of it's negative connotation; and that is the good sense to realize one's weaknesses and the willingness to give up and marshal one's resources into a more productive endeavor. Admitting one's weaknesses is understandably an unpleasant task; nobody wants to admit what they are not good at, especially if they have worked at it for years. That kind of attitude does not get you job offers or impress interviewers. Yet being able to admit what qualities you lack can make your life take a radically successful direction. And lest we think that only mere mortals have to go through this painful process of periodic self-evaluation and subsequent betterment, we can be rest assured. It was none other than Linus Pauling who went through this soul-searching. And we are all the wiser for his decision.
When Pauling graduated from Oregon State University in 1922, he had already shown great promise. At that point he had had an excellent overall education in mathematics and physics and compared to his peers in the United States was mathematically quite outstanding. In 1926 he won a Guggenheim fellowship to study in Europe under the tutelage of Arnold Sommerfeld in Munich, with trips to the great centers of physics in Copenhagen, Gottingen and Zurich included as part of the package. There Pauling met the founders of quantum mechanics, almost all of whom were about the same age, and realized that maybe his talents in physics and mathematics were not as great as he thought. There is a story, probably apocryphal, that the famously acerbic Pauli dismissed one of his papers on quantum mechanics with two short words- "Not interesting".
At this point Pauling made what was one of the the wisest decisions of his life; he decided to focus not on physics but on chemistry. He swallowed his frustration at being beaten by the best and brightest of his generation in physics and realized the great value of striking out into new territory. Why? Because his mathematical and analytical abilities, while being of considerable value in physics, would be of wholly unique import in chemistry. At that point and to some extent even today, gifted mathematicians and quantitative thinkers are quite common in physics but less so in chemistry and biology. That is precisely what makes them more valuable in the latter disciplines. In addition, Pauling had always had an empirical and experimental bent, demonstrated by his earlier research in crystallography. So chemistry it was, and the rest is history. Pauling ended up making contributions to chemistry whose significance easily paralleled that of contributions made by Heisenberg, Pauli, Dirac and Schrodinger to physics.
There are two key lessons to be drawn from Pauling's story. The first lesson is to know when to let go, to know what path on the famed fork not to take. History would likely have been quite different if Pauling had decided to be stubborn and spent the rest of his career trying to outcompete his fellow theoretical physicists. But the bigger lesson is extremely valuable for scientists wanting to make discoveries. Take a skill-set which is valuable but not groundbreaking in one discipline, and then apply it to another discipline where it will lead to novel insights and real breakthroughs. Or to put in another way, move from a crowded field where you may share your particular talent with dozens of others to one which is sparser and where your talent will be more unique, productive and appreciated. The other related lesson is to capitalize on pairs of skills, each of which by itself may not be unique but whose combination turns out to be explosive in a particular field. For instance Pauling combined his deep grounding in physics with an encyclopedic memory and a remarkably wide knowledge of chemistry's empirical facts. There were a few chemists who could marshal one or the other talent, but almost nobody could serve up Pauling's powerful one-two punch. One can find similar analogies in combinations of diverse skills like computer science and molecular biology, or electrical engineering and neuroscience.
The history of science abounds with success stories stemming from this kind of recipe. Physicists venturing into biology constitute the best example. Francis Crick was a good physicist, but he probably would not have become a great one had he stayed in physics. Instead Crick had the wisdom to realize the value of applying his physicist's mind to problems in biology and became one of the greatest biologists of the century. Walter Gilbert trained under the theoretical physics virtuoso Julian Schwinger and would have been a first-rate physicist, but applying his talents to biology enabled him to become one of the founders of molecular biology. There are also more exotic examples. The quantum physicist Tjalling Koopmans who fathered a well-known theorem in quantum chemistry did so well in econometrics that he won a Nobel Prize. In fact just like biology, economics has been another field which has been thoroughly enriched by thinkers who would have been good mathematicians or physicists but who became great economists (although the application of strict mathematical modeling in economics can lead to a world of pain). There are more local and specialized examples too. A professor of mine who is world-renowned in the physical organic chemistry of surfactants and lipids told me that he considered working in protein chemistry but realized that the field was too crowded; lipids, on the other hand, were under-explored and could benefit from exactly the kind of talents he has.
This is precisely the reason why biology is such a fertile playing field for outsiders of all stripes, from biologists and computer scientists to engineers. The kind of complex systems that biology deals with can only be unraveled through a variety of talents which people from diverse disciplines bring to the table. On one hand you need reductionist, quantitative scientists to set biology on a rigorous theoretical basis but you also need 'higher-level' thinkers who can tie together threads from disparate empirical phenomena. That's why both mathematicians and doctors continue to make valuable contributions to the field. The same can be said of chemistry. Quantum chemists like Pauling did much to root chemistry in physics, yet the sheer complexity of chemistry (after all the Schrodinger equation can be solved exactly for no atom bigger than hydrogen) demands more intuitive thinkers who can devise approximations and include empirical parameters to improve chemical prediction. Similarly, organic chemists like Stuart Schreiber and Peter Schultz were excellent synthetic chemists, but it was in the application of synthetic chemistry to biology that they found unexplored terrain and great riches.
The lesson for young scientists seems to be clear. The most explosive discoveries can result from applying talents suitable for one field to a whole new different field. And perhaps this is not surprising. Nature is not hostage to the boundaries of disciplinary convenience devised by fallible human beings and does not divide itself into rigid compartments titled "Physics", "Biology", "Approximation" or "Analytical Solutions". Nature encompasses phenomena whose analysis spans a continuum. It is hardly surprising then that she yields her secrets best to those who are more than willing to use each and every tool of analysis to criss-cross her myriad domains.