Why is the brain the most complex organ? 

The article will answer the question of why the brain is the most complex organ. It covers information on what we know and doesn’t know about the brain. In the end, the article will answer some frequently asked questions about the brain.

Why is the brain the most complex organ? 

The human brain has around 86 billion neurons, and even more synaptic connections. It may be small but is more complicated in design than the fastest computers known to us. 

After conception, the process of the human brain forming in the foetus starts at around week 5. Following this, at week 6 or 7, the neural close-up and the brain divide itself into three separate parts: cerebrum, cerebellum and the brain stem. 

While all the vital organs, along with the brain begin developing at 4 to 5 weeks of gestational age and continue developing until the last trimester, after birth, the human brain takes the longest to develop. 

While all these other organs develop fully in childhood, the human brain does fully develop until the age of 21 years old. Now you know why the legal age for drinking and getting married is 21!

Although it was previously believed that we only use 10 percent of our brain, that belief has been challenged. Modern brain imaging techniques are yet to come up with images of the human brain that display any brain areas or parts in a healthy brain that are inactive. 

Even when the human brain is at rest or sleeping, there is a great number of neurons firing and communicating with each other. In fact, the neural activity in a resting brain is much more than that of the brain of someone who has been assigned a cognitive task. Not only does this show how difficult it is to study the human brain, but it also shows how complex of an organ it is. 

Moreover, unlike many other organs, the brain is tightly packed within the skull, protected by cerebrospinal fluid. This is because the brain is immensely delicate, coordinating functions between vital organs and performing other functions essential for survival. 

Because of this, the brain also uses the most amount of energy as compared to other parts of the body. This is despite the fact that the brain makes up only 2% of our total body weight. Irrespective of whether the brain is resting or active, it consumes 20 to 25% of our total energy. 

Another contributing factor to why the brain consumes so much of the body’s total energy production is because, unlike the organs, the brain uses electrical currents to establish neural communication. 

This communication is a result of sodium, potassium and calcium ions moving across the membranes of neurons, which needs energy that usually comes about from oxidizing glucose. 

The amount of energy that the brain consumes does not reduce if there is no activity or we are sleeping. This can be attributed to something we refer to as the brain’s ‘Default Mode Network’, otherwise known as ‘DMN’. 

The default mode network is essentially a pathway of interconnected brain regions that remain active even when the brain is not engaging in any cognitive or goal-directed tasks. 

Think of the DMN as the network within the brain engaged when we are recollecting, reminiscing, thinking, watching a movie, listening to a podcast, or doing anything else which is passive. The DMN never quiets down. 

As soon as this network finishes with one task, it immediately starts with another, all within a fraction of a second. To put it simply, we never stop thinking. Not only does the brain never rest, and is always engaged in some form of thinking- it is also able to carry out multiple tasks simultaneously. 

Consider the mind-boggling number of activities the brain is engaged in as you read this. The brain is ensuring that your fingers hold the device you’re reading it on and that your eyes are focused on the words; if you’re reading on a phone or tablet, the brain is ensuring hand-eye coordination so that you can hold the device as a proper distance. 

Most importantly, the voice in your head is reading the words aloud for you as the brain tries to make sense of the many words on the screen. 

These are the number of tasks the brain is engaged in for a simple activity like reading. Consider the amount of activity that takes place when the brain is engaged in something much more complicated, like solving a Rubik’s cube or painting scenery. Moreover, the brain can also carry out two different tasks that are not connected to each other at all. 

For example, when someone is talking about something you’re not necessarily interested in, so you’re pretending to listen and thinking about how to escape the conversation at the same time; or when you’re listening to music while studying. 

Add to that the tasks required to keep the human body alive and functioning at its optimal level. While we go on and about our day-to-day activities, the brain is working in the background coordinating all the vital organs, as well as the different brain pathways and regions to ensure that these organs are performing their functions as per our requirements. 

Whether it is our breathing, digestive system, the heart pumping blood all over our body to reach other organs, or the pineal gland and hypothalamus working in tandem to release appropriate hormones when required- the brain does it all, along with the cognitive and goal specific tasks we carry out every single day.

At the end of the day, when we wrap up our work and go to sleep- the brain is still functioning. In fact, the most important aspects of brain development take place while we’re at rest. 

This is said because the brain undertakes repair and rejuvenation work while we’re at rest. Moreover, other important functions like consolidation of memory and incubation of creative ideas happen while the brain and body are at rest during REM sleep. 

Understanding the human brain better would help us in enhancing these procedures, whether it be through food, supplements or activities that would boost these processes. 

All these are the reasons why it is important to keep our body and brain nourished. Having a wholesome diet, eating sufficiently and on time, and engaging in some form of body movement or exercise, go a long way to ensure that our brain continues to be able to meet our needs, while constantly ensuring that our organs are in the best shape, and launching repairing procedures when they’re not. To understand more about the functions of the brain, click here.

This goes to show the level of complex processing the human brain is capable of, and why understanding it would benefit us.


The article answers the question of why the brain is the most complex organ. It covers information on what we know and don’t know about the brain. In the end, the article will answer some frequently asked questions about the brain.

Frequently Asked Questions: Why is the brain the most complex organ? 

What are some of the important functions of the brain?

The brain governs intelligence, creativity, emotional processing and regulation, and memory.

What was Albert Einstein’s IQ?

It is said that Albert Einstein had an IQ of 160. 160 is the maximum IQ score that can be attained by using The Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV) that was put forward by Wechsler (1949). An IQ of 135 or above means the person is in the 99th percentile of the population. Various news articles claim that Einstein’s IQ was 160, however, the methodology they use for this estimate is unclear.

How much power can the brain generate?

The human brain generates around 23 watts of power, which is enough to power a lightbulb. This power calls for the need for rest. Good sleep helps in maintaining the pathways in the brain. Sleep deprivation can increase the accumulation of a protein in the brain which is linked with Alzheimer’s disease.

What kind of matter is present in the brain?

The central nervous system is comprised of two different brain regions. The Gray matter and the white matter. In brain regions, the grey matter is the darker, outer region of the brain, while the white matter is the inner lighter region of the brain. 


Wechsler, D., & Kodama, H. (1949). Wechsler intelligence scale for children (Vol. 1). New York: Psychological corporation.