The discussion of human intelligence has always been a sensitive one, as if the very idea that a person can be born biologically less intelligent than another is taboo. The idea that a person can be born with biologically superior athleticism to another seems far more accepted. Yet intelligence must be discussed as it holds a singular importance in understanding our continued evolution as well as the issues that face our modern world. 

From a biological perspective human intelligence is based on the interactions amongst the billions of neurons in the brain. A higher level of intelligence is tightly correlated with a greater speed of neuronal communication between the various areas of the brain. However, scientists believe that human evolution has arrived at a bottleneck when it comes to intelligence; the brain’s biological structure is inherently limited by its constituent elements, namely the proteins used to produce electrical impulses. An increase in brain size (i.e. more neurons and specialization) or a decrease in neuron size (i.e. faster communications) would simply increase the inefficiencies in the communication process.


Similarly, though engineers have managed to steadily shrink transistors over the past five decades, transistors are now so small that any further decrease in size would allow the presence or absence of a single atom to render their behavior erratic. Though engineers could theoretically start afresh with entirely new technologies, evolution cannot. Biologically, it seems that Homo sapiens sapiens is as smart as he will ever be [1].

In psychology the concept of human intelligence has a multi-faceted definition due to the variety of ways in which the neurobiology described above can manifest itself in an individual. The ability to learn from experience, reason logically, understand abstract concepts, use knowledge to shape one’s environment, and adapt to new situations are all elements of intelligence. Psychologists have fiercely debated which parts of this definition are more important than the others. Even psychologists working in the same field have focused on different parts; for example, though both Edward L. Thorndike and Lewis M. Terman were pioneers of educational psychology, the former emphasized learning while the latter focused on thinking abstractly.

Multiple intelligences

These disagreements have resulted in numerous conflicting theories, including the Cattell-Horn-Carroll Theory, the Triarchic Theory, the Theory of multiple intelligences, and the PASS Theory, all of which attempt to describe intelligence by breaking it down in different ways. Today psychologists generally agree that the ability to adapt to the environment is central to understanding both the nature and the function of intelligence [3].

A study by Satoshi Kanazawa, a professor at the London School of Economics, published in the March 2010 issue of Social Psychology Quarterly, supports the correlation between human intelligence and adaptation. Kanazawa’s research found that “more intelligent people are statistically significantly more likely to exhibit social values and religious and political preferences that are novel to the human species in evolutionary history”. His results show a relatively small, but nonetheless important, difference in intelligence between people exhibiting novel rather than familiar behavior.

During adolescence, young adults describing themselves as "very liberal" have a mean IQ of 106 versus a mean IQ of 95 for their "very conservative" counterparts; young adults describing themselves as "not at all religious" have a mean IQ of 103 versus a mean IQ of 97 for their "very religious" counterparts.

Conservative vs Liberal

Kanazawa explains that humans are genetically designed to be conservative (caring primarily about family and friends), religious (perceiving agency behind natural phenomena), and –in men– mildly polygynous (not expected to be sexually exclusive when in a polygamous marriage). Though these values and preferences were advantageous thousands of years ago, in the modern developed world such behaviors are problematic since they have become counterproductive. Intelligence (in this case defined as the ability to reason), Kanazawa concludes, provides a solution to this problem by creating a preference for evolutionarily novel behaviors, ones that humans are not biologically designed to possess. In practice this means that liberalism, atheism, and –in men– sexual exclusivity are all positively correlated with a greater level of intelligence [2].

Since research has shown that the topic of human intelligence is highly connected to adaptation it is of the utmost relevance today. In the span of the past century the world has changed more than in the previous tens of millenia. With each passing year the rate of sociological change accelerates as scientific and technological knowledge builds to unprecedented levels.

Understanding the nature of human intelligence and how it allows adaptation to the environment is therefore more crucial than ever in order to deal with the uniquely challenging problems of the 21st century. Undoubtedly, mapping the brain is one of the next great scientific frontiers. Highly misunderstood, often overrated, intelligence is a topic that always surprises me whenever I discover another of its countless nuances.