Evolution Of The Human Brain
Comparative studies have suggested that there are general architectural principles that govern the growth and evolution of our brain. Through these studies we began to understand the geometric, biophysical and the energy constraints that have governed the evolution and functional organization of the brain as well as its underlying neuronal network. Evidence has shown that the development of the folding of the cortex (the more foldings the more neural connections) produces smaller and faster brains. The human brain consists of about 100 billion neurons, that is more than 100,000km of interconnections. Such numbers have led us to believe that our cognitive capabilities are virtually without limit.
Our brain, however, has evolved from a set of underlying structures that constrain its size, and the amount of information it can store and process. If we consider the ability of an organism to process information about its surrounding environment as the driving force behind its evolution, then the more information a system (in our case the brain) receives, and the faster this information is processed, the more chances of the organism to survive. The limit to any intelligent system lies in its ability to process and integrate large amounts of sensory information and to compare these signals with as many memory states as possible, and all that in a minimum of time. This implies that the functional capacity of our neuronal structure is inherently limited by its neural architecture and signal. In this article, some of the organisational and operational principles will be explored that underlie the information processing capacity of the human brain.
In higher organisms, especially in primates, the complexity of the neural circuit of the cerebral cortex is considered to correlate of the brain’s coherence and predictive power and, thus, a measure of intelligence. The evolutionary expansion of the cerebral cortex, is among the most distinctive features of mammalian brains. In species with large brains, for example in great apes and marine mammals, the brain becomes disproportionately composed of this cortical structure (the size of the entire cerebral cortex goes from 40 % in mice to about 80 % in humans). It is clear that the cerebral cortex is not the only brain structure involved in the evolution for greater growth, but it has played a key role in the evolution of intelligence.
As mentioned above, the human brain has evolved from a set of underlying structures that constrain its size and the amount of information it can store and process, there are however a few limits to the evolution of the brain.
1.Energetic limits: our brain can generate up to about 15 watts in a well insulated surrounding. This can cause a problem of overheating of the brain; the removal of sufficient heat to prevent thermal overload can be a significant problem.The solution to this is that the brain is actively cooled by the blood. The limiting factor here can be how fast the heat can be removed from the brain by the blood that is flowing.
* It is also worth recalling that Aristotle, the greatest natural scientist of the ancient world, maintained that the heart was the seat of thinking and emotion, assigning the brain only the function of cooling the heat generated by the heart; which is in fact the opposite of what happens.
2.Neural processing limits: the limit to any neural system lies in its ability to process large amounts of information in a given time period and therefore, its functional capacity is essentially limited by its architecture and signal processing time. It is argued that the human brain has reached the limits of information processing that a neuron based system. Any further enhancement of human brain power would require a simultaneous improvement of neural organization, signal processing, and thermodynamics. The larger the brain grows beyond this critical size, the less efficient it will become, thus limiting any improvement in cognitive power.
In conclusion, with the evolution of the sensory systems, not only has the capacity to process large amounts of information increased but also the power to create more complex physical realities.
Ishika Kriplani — Psych Club