Every once in a while someone will publish a list of the top 10 or 100 smartest people in the world and this time it's the Huffington Post's turn. While admitting that IQ is subjective, the article treats us to a list of ten people who most of us would agree are on the right tail end of the spectrum of intelligence. As usual, what's interesting is what is left out. The list seems to lean disproportionately toward child prodigies with high IQs and the scientific side leans completely toward physicists and mathematicians. This is not unusual; if you are talking about science and ask a layman who he thinks are the most brilliant scientists in history, you are more likely to hear the names of Einstein, Feynman and Hawking rather than Darwin, Crick and Pauling.

I have always though this kind of math-centric view of intelligence to be a little biased and exclusionary. Chemists and biologists would overwhelmingly agree that Linus Pauling and Charles Darwin were geniuses akin to Einstein and Feynman in their own fields. The same would be true for T S Eliot in literature and Edward Gibbon in history. Yet for some reason, partly based on some rather valid historical facts of twentieth century physics which we will shortly explore, people's ideas about intelligence in science are biased toward mathematical fields in which raw IQ and innate talent can sometimes matter to a disproportionate extent.

The inclusion of child prodigies in assessments of intelligence is another highly context-dependent metric that can sometimes mislead. It's common to point to someone getting into MIT at age 15 as a necessary and sufficient indicator of their intelligence. But it's far more common to find child prodigies in math and physics than in other fields (I know only one chemist for instance who can be regarded as a truly chemical child prodigy: R B Woodward). This lack of correlation between child prodigies and accomplishments is even truer for non-scientific fields; when was the last time you heard about a child prodigy in history? The fact is that prodigies are often likely to make major contributions later in their life, but the converse is not true; most accomplished scientists in fact were not child prodigies when they were growing up. And although much of their stories are apocryphal, some such as Einstein and Edward Teller were rumored to be alarmingly stunted in their early intellectual development. Even among theoreticians at the far end of the scale, child prodigies are not as common as we think.

A third kind of bias leads to equating youth with intelligence, and this is again a metric that applies mainly to mathematical fields along with a few other areas like computer science and, occasionally, entrepreneurship. Here's a point of reference: many Nobel laureates in physics were between 25 and 35 years of age and predominantly theoreticians whereas the youngest economics Nobel laureate (Kenneth Arrow) is 51. Ironically, the youngest Nobel laureate in physics (Lawrence Bragg at age 25) was not a theoretician but a lowly experimentalist. Francis Crick was a notoriously old scientist in his mid-thirties when he c0-discovered the structure of DNA, a discovery following which he rose to become the leading light of molecular biology. My own scientific field of drug discovery provides another example of a profession in which people who are regarded as very smart overwhelmingly tend to be older, experienced scientists rather than young researchers, let alone child prodigies. You will be hard pressed to find a 20 year old who discovered a bestselling drug. In fields other than math and theoretical physics, older accomplished scientists routinely tend to be the rule rather than the exception. In fact a recent analysis in the Proceedings of the National Academy of Sciences confirmed this trend by looking at the mean age of Nobel Prize winners; not surprisingly, the authors found that younger winners are disproportionately represented in the physical sciences compared to economics and the biological sciences.

Why is the relationship between raw IQ, child prodigies and youth truer for math-oriented fields? One simple answer is that success in fields other than math and theoretical physics depends much more on factors other than innate talent, flashes of inspiration and abstraction and number crunching. For instance it often depends on extensive data-gathering which can only come from practice and experience. The reason why it's difficult to find young accomplished scientists in drug discovery is because discovering a new drug is a complex, multidisciplinary process requiring teamwork, intuition and a hodgepodge of diverse skill sets that benefit more from those proverbial 10,000 hours of practice than from incisive mathematical analysis. Mathematics also needs its ten thousand hours, but raw powers of abstraction can also contribute much to mathematical success. The essential role of experiment in certain fields also makes it difficult for child prodigies to succeed; for instance, even a prodigy with a stratospheric IQ would not be able to discover a new protein involved in photosynthesis since this discovery would require access to sophisticated instrumentation which he or her would likely not have until college. The disconnection is even more true for the humanities like history or literature where constant practice and a studied appreciation of the human condition is essential to understanding and success; Richard Rhodes and James Michener for instance produced their best work only in their 40s. All these skills are of course not inapplicable to mathematical fields, it's just that they are often essential for success in non-mathematical fields.

There could be many reasons for why our evaluation of intelligence is still biased toward mathematical disciplines, but one that comes to my mind is a historical accident culminating in the extraordinary success of twentieth century physics. Consider that the person synonymous with the word genius is Albert Einstein, not Linus Pauling or T S Eliot. Especially in the twentieth century, the insights revealed by physics were so philosophically startling (relativity, quantum theory) and practically devastating (nuclear weapons) that it was easy to think of physicists - some of whom were indeed geniuses - as magicians who simply sat in their chair thinking and discovered great truths about the universe, and not just ones which could probe the deepest recesses of the atom but which could fashion thermonuclear weapons. Physicists become role models for intelligent people. One would have thought that the spectacular development of molecular biology would have catapulted its practitioners to the same hallowed status but this does not seem to have happened at least in the earlier stages, probably because discoveries in physics still held enormous sway and partly because even molecular biology benefited from the kind of reductionist approach that proved so fruitful in the physical sciences. Another reason why assessments of intelligence leaned toward physicists was also because the advent of quantum theory made it possible even for "lesser" minds to make major discoveries. This did not mean that the lesser minds were dim bulbs, but the cornucopia of experimental data that could suddenly be explained by quantum theory meant, in Paul Dirac's words, that even "second-rate physicists could make first-rate discoveries." The simple fact of the matter is that when a whole host of phenomena in a field suddenly become amenable to explanation using a newly discovered paradigm and tool, even scientists of modest gifts can potentially make major contributions. This is what happened with physics in the early twentieth century.

It is time for our assessments of intelligence and genius to become more inclusionary. The authors of the aforementioned study also point out the curious fact that even among Nobel laureates in the physical sciences, the average age of the winner increased from the early years of the twentieth century to its later years. One simple reason was that science was in a sense becoming harder, requiring more sophisticated instrumentation, collaboration and grantsmanship. Even in a field like theoretical physics the bar has been set high; there has been no truly groundbreaking discovery for forty years and the best candidate for a reworking of physics, string theory, is not just tenuously connected to experiment but also suffers from criticisms regarding its lack of concrete testability. In other fields the requirements for interdisciplinary approaches, teamwork and extensive data analysis are even more extensive. Yet another reason which I speculated about earlier is that much of the modern practice of science is inductive rather than deductive, leading an older person with a wealth of facts and experience at his or her disposal to have a better chance of making connections and crossing interdisciplinary boundaries. Finally, the sheer scope of science has enormously expanded, making it impossible even for a genius to digest the wealth of scientific facts available. Young people will continue to bring valuable spirit and innovation to research but it's likely that they won't be in a wholly privileged position to influence scientific discoveries.

All this may mean that the list of the ten smartest people in 2050 may not include just the Math Olympiad Gold Medalist who went to graduate school at Harvard at age 15. Science may just not work that way then.