Discovering genius: The neurobiological substrate of intelligence

Helena Ljulj
Zagreb, Croatia


Depiction of physiognomy. Profiled Series by Ken Gonzales-Day, 2009. Getty Museum. Image courtesy of the artist and Luis De Jesus Los Angeles.
Left: Bust of an African Woman by Henry Weeks, 1859.
Right: Bust of Mm. Adélaïde Julie Mirleau de Newville, née Garnier d’Isle by Jean-Baptiste Pigalle, 1750s.

“It is by the shape and size of the forehead that we are to judge of the extent of a man’s understanding… When the frontal vein appears distinctly in the midst of a forehead, open, uniform, and regularly arched, it announces extraordinary talent.”1


According to the eighteenth century physiognomist Johann Caspar Lavater, these are the physical characteristics of a brilliant man.

Attempts to find the neurobiological substrate of intelligence date back to at least 400 BC. Hippocrates and Galen recognized that the origin of mental processes resides in the brain rather than in the heart,2,3 raising such questions as to whether a bigger brain implies “extraordinary talent” and whether geniuses are born or made.

Lavater in The Pocket Lavater, or, The Science of Physiognomy,4 explains how “the various thoughts which arise in the mind, the different passions which agitate the soul of man, are respectively connected with his features and the external parts of his frame.”5 In other words, physical appearance indicates intelligence.

In the early nineteenth century, German physician Franz Joseph Gall sparked the pseudoscience of phrenology, which, in a similar vein to Lavater, linked the external features of the skull with personality traits and intelligence.6 He believed that intelligence could be evaluated by examining the skull and feeling for the presence of the so-called “organs of the mind.” Specifically, he felt that genius demanded a maximal development of these organs: “Genius is the result of a very fine constitution, great activity, and a large development of the brain. In a universal genius, all of these elements must be combined; while in a partial genius, only some of the organs may be large.”7 He further suggested that, in particular, the size of the anterior lobe is the measure of intellect.”8

The French neurologist Paul Broca, however, disagreed and showed that different parts of the brain had different functions. He studied the relationship between brain size and intelligence in workers and in 1861 reported that people engaged in more complex tasks had larger brains than those working on less complex ones.9 His findings led to an interest in brain size, and the exterior physical appearance of the head and face became unimportant. The question remained: does a larger brain indicate genius?

Lateral view of Einstein’s brain, prior to sectioning. Harvey Collection, National Museum of Health and Medicine.

At the turn of the twentieth century, scientists probed the brain of intellectual giant Carl Friedrich Gauss10 and, later, that of Albert Einstein,11 for a biological indicator of intelligence. As early as 1907, a paper12 summarized the weights and patterns of cortex gyrification of 137 distinguished persons. In another study it was found that Gauss’s brain weighed 1,492 grams and was heavier and more gyrified on its surface than that of the average male.13 Einstein’s brain weighed only 1,230 grams, less than the average male brain.13,14 However, its dissection revealed an absence of the parietal opercula, a bilateral confluence of the Sylvian fissure and the postcentral gyrus,11 and a more developed corpus callosum, perhaps accounting for his great mathematical and visuospatial cognition.15 The question shifted once more: if the weight of a brain and its neuroanatomical landmarks are no longer the markers of intelligence, is it possible that each genius possesses a unique neuroanatomy?

In the late twentieth century, the development of magnetic resonance imaging led to new studies.16,17 These shed light on an underexplored factor: environment. According to Dr. Osvaldo Cairό, “The fundamental study of key scientific findings seems to show that genotypes are responsible for defining the theoretical limits of intelligence, but the experience (environment) is largely responsible for determining whether those limits will be reached or surpassed.”17 Put differently, intelligence genius would result from unique interplay of genetics and environment.

If environmental influence is so significant in determining intelligence, can anyone become a genius? Psychologist Frank Lawlis of Mensa writes, “The geniuses ask questions. They don’t know the answers, but they know a lot of questions and their curiosity takes them into their fields.”18 This capacity for inquiry is something all humans possess, especially at a young age.19 If this capacity for curiosity develops into a higher level of intellectual exploration, it seems that extraordinary intellectual ability is potentially universal. Provided they have access to nurturing learning opportunities, it results that even “ordinary” individuals can tap into this potential.



  1. Lavater JC. The Pocket Lavater, or, The Science of Physiognomy: To Which Is Added, An Inquiry into the Analogy Existing between Brute and Human Physiognomy, from the Italian of Porta. Hartford: Andrus & Judd; 1832. p 22-24.
  2. Finger S. Minds Behind the Brain: A History of the Pioneers and Their Discoveries. Oxford University Press; 2004.
  3. Findlen P, Bence R. A History ofthe Brain. Early Science Lab. Stanford University.
  4. Lavater JC. The Pocket Lavater.
  5. Lavater JC. The Pocket Lavater, p. 15.
  6. Spurzheim JG. The Physiognomical System of Drs. Gall and Spurzheim: Founded on an Anatomical and Physiological Examination of the Nervous System in General, and of the Brain in Particular; and Indicating the Dispositions and Manifestations of the Mind. 1815.
  7. Combe G. Elements of Phrenology. 1855. p. 164.
  8. Combe, Elements of Phrenology, 38.
  9. Broca P. Sur Le Volume et La Forme Du Cerveau Suivant Les Individus et Suivant Les Races. 1861.
  10. Donaldson HH. Anatomical Observations on the Brain and Several Sense-Organs of the Blind Deaf-Mute, Laura Dewey Bridgman. American Journal of Psychology 1891;4.
  11. Witelson SF, Kigar DL, Harvey T. The exceptional brain of Albert Einstein. The Lancet. 1999;353(9170):2149-53. doi:10.1016/S0140-6736(98)10327-6.
  12. Edw. Anthony Spitzka. A Study of the Brains of Six Eminent Scientists and Scholars Belonging to the American Anthropometric Society, together with a Description of the Skull of Professor E. D. Cope. Transactions of the American Philosophical Society 1907;21.
  13. Hartmann P, Ramseier A, Gudat F, et al. Normal weight of the brain in adults in relation to age, sex, body height and weight. Pathologe. 1994;15(3):165-170. doi:10.1007/s002920050040.
  14. Pais A. Einstein Lived Here: Essays for the Layman. Oxford: Clarendon Press; New York: Oxford University Press; 1994.
  15. Men W, Falk D, Sun T, et al. The corpus callosum of Albert Einstein‘s brain: another clue to his high intelligence? Brain. 2014;137(4):e268. doi:10.1093/brain/awt252.
  16. Pietschnig J, Gerdesmann D, Zeiler M, Voracek M. Of differing methods, disputed estimates and discordant interpretations: the meta-analytical multiverse of brain volume and IQ associations. R Soc Open Sci. 2022;9(5). doi:10.1098/rsos.211621.
  17. Cairό O. External measures of cognition. Front Hum Neurosci. 2011;5. doi:10.3389/fnhum.2011.00108.
  18. Deamer K. Genius: Can Anybody Be One? Live Science.
  19. Zimprich D, Allemand M, Dellenbach M. Openness to Experience, fluid intelligence, and crystallized intelligence in middle-aged and old adults. J Res Pers. 2009;43(3):444-54. doi:10.1016/j.jrp.2009.01.018.



HELENA LJULJ is a fourth-year medical student at the University of Zagreb School of Medicine, Croatia. Curiosity since childhood led her to question how our brain fosters our identities and our perception of reality. She aspires to use her neuroscience knowledge to make meaningful advances in medicine.


Submitted for the 2022–23 Medical Student Essay Contest
Spring 2023  |  Sections  |  Neurology