What Effect Has Evolution Had on The Human Brain Thus Far?


The most complicated object in the known universe is the human brain. On average, our brain contains about eleven billion neurons. Each one working to send, receive and process electrochemical signals. Our thoughts, emotions, movements and very existence are dependent on processes within the brain that are still largely a mystery to us. One may wonder how such a wondrous and complex organ came to be. It is here that we begin to decipher the effect of evolution on the human brain.

Assuming the theory of evolution, that organisms more suited to their environment can survive better and mate, it makes sense that, somehow, having a larger and more complex brain makes survival on Earth easier. Indeed, if one were to look at the brain size of our hominid ancestors from four million years ago, it would be discovered that their brains were a mere 400 grams. Compare that to the present size- over 1400 grams (1.4kg).

But it was more than sheer size that changed, but the actual structure of the brain. What happened earliest was the centralization of the brain’s nerve cells. What started as a loose and messy grouping of cells that would be seen in a jellyfish, turned into a spinal column and enlarged fore- and hindbrain. These parts of the brain that are relatively new are known as neocortical, literally “new brain”. Actually, things such as our abilities to speak, plan, and be conscious of our own existence depend on neocortical structures. This means that when the brain became more complex, we gained a completely different way to interact with our world. Language allowed humans to organize themselves and hunt more effectively- and having a larger and more complex brain allowed a higher capacity for intelligence, thought, and planning. These are all things that gave humanity an advantage against predators, prey, and the world’s wide variety of dangerous natural elements.

The brain also experienced a phenomenon known as encephalization, which is the concentration of sense organs and neurons in one part of the body. This is why the brain, olfactory sense, hearing, and sight are all housed in the head. This made it easier for the brain to work because the signals that neurons use wouldn’t have to travel as far if the brain is all in one place.

Evolution caused the brain to become larger, more complex, and more efficient. Much how we make our computers with more space, more speed and efficiency with every new generation (this excludes Apple, of course). There is certainly is proof of our brain’s effect on the world. Humans are definitely a thriving species. One may also consider the worldwide subjugation and abuse of animals to be proof of our dominance as a species.

But it is important to remember that neurology has only scratched the surface when it comes to the human brain. There are still plenty of things we don’t know, actually we don’t know most things. There could be all kinds of secrets within the brain waiting to be unlocked, like other senses, the power of thought, or ways to become more intelligent faster. All this would also make one wonder what evolutionary stage the brain will achieve in another thousand years.

Works Cited:

Brain evolution. (2010). Retrieved from http://www.youramazingbrain.org.uk/insidebrain/brainevolution.htm

Evolution and the brain. (2010). Retrieved from http://www.nature.com/nature/journal/v447/n7146/full/447753a.html

Without miracles 5 brain evolution and development. (2010). Retrieved from http://faculty.ed.uiuc.edu/g-cziko/wm/05.html