This is a question that has haunted mathematicians and physicists as well those in other high IQ professions. In 1927, physicist Paul Dirac, who won a Nobel Prize at age 31 for his work in quantum physics, wrote the following quatrain:
Age is, of course, a fever chill
That every physicist must fear.
He’s better dead than living still,
When once he’s past his thirtieth year.
In the 1940’s Raymond B. Cattell proposed that human intelligence is composed of two parts: fluid intelligence (measured by IQ) plus crystallized intelligence (accumulated knowledge and experience). It has been discovered that our fluid intelligence reaches its maximum in early adulthood and then enters a gradual decline into senescence. However, the decline in fluid intelligence is slow and is more than compensated for by an increase in crystallized intelligence as we age, so our total intelligence (called g) reaches a peak somewhere in middle age, depending on the skills measured.
The following excerpt from Intelligence, IQ & Perception (chapter 5) shows the ages at which those working in the natural sciences do their best work.
… in 1991, Simonton published a comprehensive study of 1825 scientists and inventors in which he used a variety of criteria to assess the ages at which the cognitive elite in a variet ,y of fields produced their first, best, and last creative work. Though assigning a precise time to the “best work” is somewhat subjective and therefore approximate, the trends have been identified by averaging these data for a significant number of individuals in each discipline. Table 5-3 presents the mean ages at which scientists in various domains of the natural sciences reached these three milestones in their careers.
Table 5-3 reveals that on average, a scientist’s creative productivity begins near age 30, attains a peak around the 40th year, and gradually comes to a close shortly after age 50. Furthermore, the mean age at which mathematicians do their best work is 38.8 years, with a standard deviation of 10.7 years. Assuming that these ages are normally distributed, we can conclude that about 45% of mathematicians do their best work at or slightly beyond 40 years of age. Similarly, almost half of the physicists and chemists achieve peak performance soon after age 40. Therefore, the belief that all researchers in science and technology are doomed to mediocrity after age 40 is not supported by the data. As Simonton observes, “many of these notions [from biographies and historical chronologies] in fact take the explicit form of ‘myths,’ such as the recurrent statement that physicists are ‘over the hill’ at age 30.”
We observe similar patterns in achievement in the arts, the social sciences, and chess, although the ages at which the best works are created varies across disciplines. The causes of the decline in fluid intelligence are attributed to a decrease in neural efficiency, though the physiological causes of this decrease are not well understood. Based on informal personal observation over the past few decades, I would suggest that those who engage regularly in high level intellectual tasks, suffer a slower decline in mental acuity than others, though I have no research data to support my conjecture.
