Is There a Limit to Our Intelligence?

At his request, so that his resting place would not become the subject of "morbid veneration", Albert Einstein's body was cremated and scattered into the Delaware River. All but his brain, that is. The journey that Einstein's brain undertook after it's body's passing is an adventure in and of itself, traveling cross country in the back of his pathologist's Ford in a couple of glass cookie jars. But for all of the effort, only three significant scientific studies were published about the genius' thinking machine. One study observed that Einstein had a higher than normal ratio of glial cells to neurons in his parietal cortex, and speculated that this meant his neurons needed and used more energy. Another study suggested that his cerebral cortex was thinner than normal and contained a higher density of neurons. The third showed that the area of his brain most responsible for mathematical and spatial thinking, the inferior parietal lobe, was 15% wider than normal. Were the biophysics of Einstein's brain maximized so as to grant him some ultimate level of intelligence? Or was Einstein's brain merely the best that evolution has designed up to this point with far more powerful still to come?

Many scientists now believe that the brain cannot get smarter ad infinitum. They propose, rather, that there are physical roadblocks that limit the expansion of neuron-based processing power. Furthermore, it is likely that the current human brain is very close to this limit. There are four ways in which a brain can increase its processing power: add more neurons, increase the amount of connections between neurons, speed up the communication between neurons, and increase neuron density. However, these four factors cannot all be maximized simultaneously after a certain point; increasing one factor begins to decrease another. For example, adding more neurons boosts processing capacity, but it also makes the brain larger and thereby slows neuronal communication. Decreasing the size of neurons to pack them more densely speeds communication, but beyond a lower limit signaling becomes too noisy and neurons fire randomly. (See Scientific American's The Limits of Intelligence for a more detailed account of the brain's physical limits).

All of this seems very valid, but the analysis seems to have neglected an important component. The brain may be approaching it's limit to the amount and quality of raw processing material it possesses, but life is far from the limit of being able to fully utilize this material, if such a limit even exists. The majority of human beings, by means of their own faculties, are only capable of using a percentage of their brain's power. A telling example comes from comparing one's sober, waking state cognitive abilities to one's cognitive abilities under the influence of a psychedelic. In the latter condition, many are capable of exquisite visual memory and spatial thinking abilities that they cannot access in a normal state. The brain's power is also limited by the sensory organs that provide it with information about the world. After all, the brain sits in a dark cavern inside our skulls, completely disconnected from what is going on outside by any direct means. Perhaps the parts of our bodies that interact with reality firsthand can be perfected.

And of course, intimately tied to all of these questions is the question of whether there is an ultimate level of reality. If our brains can actually reach some level of ultimate intelligence, will this coincide with being able to perceive and understand the true nature of reality? And what for individuals who claim to undergo spiritual or religious experiences that put them in touch with this ultimate state of being? What are their brains doing during these experiences? Do these experiences even invoke the brain?