In 1848 a young naturalist named Alfred Russell Wallace sailed from England to Brazil to gather specimens in the Amazonian rain forest in the hope of finding clues to the origin of species. On the return voyage, the ship caught fire and sank, and much of Wallace's collection was lost. Undaunted, he set sail two years later for the East Indies, where he collected more specimens on the Malay Archipelago. In 1858, Wallace wrote a letter outlining a radical new theory of natural selection that he sent to an older colleague who had established his reputation in the field with a similar voyage some years before on the H.M.S. Beagle. Wallace knew his colleague was interested in the origin of species but did not realize Charles Darwin had been quietly working on the same theory for 25 years. Wallace's letter spurred Darwin to action. Papers by each man were read jointly at the Royal Society, but Darwin's findings claimed precedence, and he is now credited with the theory of evolution.
Evolution is merely one of many notable scientific discoveries that occurred more than once. Newton and Leibniz quarreled over which of the two deserved credit for the calculus, which each had developed independently using different notation. Julius Robert von Mayer and James Prescott Joule had rival claims on work leading up to the principle of the conservation of energy, which was formulated by Hermann Helmholtz in the 1840s. At about the same time, Urbain Leverrier and John Couch Adams separately predicted the discovery of Neptune, based on irregularities in the orbit of Uranus. And Alexander Graham Bell and Elisha Gray filed telephone patents on the same day, triggering legal disputes that were not resolved until both patents were purchased by the same company.
The sociologist Robert Mertons believed the phenomenon of multiple scientific discovery is more the rule than the exception. In our time and culture, we look to the one who is inspired rather than to the source of inspiration. And yet, were it not for accidents of history, we might just as easily be celebrating the genius of a Wallace, a Leibniz or an Elisha Gray, rather than remembering them as also-rans. In the scientific realm especially, the process of discovery tends to be cumulative. Once the groundwork has been laid through prior discoveries, the next breakthrough is just waiting around for someone to stumble upon it.
But not just anyone, it would appear. While in theory you can equip a bunch of monkeys with typewriters and eventually get the works of Shakespeare, the reality is that Shakespeare's plays were not even produced by a bunch of Elizabethan playwrights; they were the work of a solitary genius. Multiple scientific discovery can describe a single breakthrough achieved by more than one person or a single person who achieves more than one breakthrough. Einstein's work of a single year (1905) probably deserved three Nobel Prizes, and the one he was awarded had nothing to do with the theory of relativity.
Inspiration literally means "breathing in," and there is certainly a sense that new ideas are in the air, waiting to be taken in. Since we all breathe the same air, it is not surprising that some ideas can prove contagious -- or that it can be difficult later to determine who caught them first. Some of us are clearly more susceptible to this kind of contagion than others. But we would do well to remember that even if we breathe more rarified air than the rest, we do not supply the oxygen.