The idea of a ‘mind’ is a useful concept as such. It allows us to discuss an extremely complex collection of mental and physical phenomena that are going on in the brain as if there would be just only one single issue of a 'mind'. In the end, we talk about the products of incredibly varied and complex brain-processes when we discuss any area of human behavior.
Of course, the birth of an idea of a single indivisible ‘mind’ is caused by the fact that there is always the conscious 'me' on the very topmost level. This conscious 'me' processes the finished end-product of all of the incredible activity that going on under the hood in a human brain all the time.

Between the conscious or the ‘me’-part of the brain and the immensely diverse and highly active subconscious part, there is a web of complex gate-keepers. They keep out from the conscious part the multitude of continuous routine-processes that are always going on beneath in the subconscious part of the brain. (See http://eagleman.com/eagleman-blog/135-the-mystery-of-expertise-full)
Without all this gate-keeping that is going on without a single pause for the duration of our life, the conscious part of the brain would be overwhelmed in seconds. Millions of years of human evolution have decided which is the right level of information that we need in the conscious level. Same process has decided which information can be left to the subconscious part of the brain to deal with. This naturally varies incredibly at different situations.

Some of these processes keep our body alive. They do it by detecting when our body needs things like oxygen, water or food. Some of the follow our mental state. Some of them follow what happens around us. These are things that the brains of all living creatures share. They are always necessary if you want to stay alive if you are a mollusk or a human.
On the other hand, comparing the human brain to a simple computer is also utter reductionism in the other direction. We have not been able to produce computers that could even challenge the immense complexity and most of all immense flexibility of the human brain.

A human brain is not a computer, but one can say that it consists of hundreds or thousands of immensely effective parallel processors. They are constantly activated and de-activated on ad-hoc -basis to solve the current problems and tasks. All these processors have unlimited parallel access to nearly endless amounts of working memory and nearly as endless amount the storage space for their results.
According to recent figures human brain has also around 100 billion neurons. The real secret of the brain is that all of these neurons are perpetually establishing and breaking connections, known as synapses, with other neurons and creating continually new networks.

In the end, it was the subconscious part of my brain that did come up with the idea that I should write this little essay. I did not control this original though-process on a conscious level. However, I did finally analyze the idea on the conscious level and decided to write it out here.
It is easy to understand how the early people could not understand the workings of this subconscious part of the brain at all. It is also easy to see how they could have seen as these ideas and thoughts as they would be coming from somewhere outside themselves. In fact, many of them clearly thought that their ideas were coming from some kind of 'deity' or 'spirit'. If you look at oldest literature armed with this idea, you very soon see what I mean.
The same phenomena do explain also the amazingly common ideas among believers that they are constantly in touch with their chosen deity, and this ‘divine voice’ also guides their lives in many ways. However, I’m afraid that instead of any divine voice, they are listening to the subconscious part of their own brain. It does process things in its own pace and answers can surface even quite unexpectedly.

Neurons generate electrical signals that travel along their axons. When a pulse of electricity reaches a junction called a synapse, it causes a neurotransmitter chemical to be released, which binds to receptors on other cells and thereby alters their electrical activity. - Wikipedia

Again; the idea of a ‘mind’ was invented to simplify the handling of a phenomena that was all too complex for the early people to comprehend at all. They just could not even imagine how there could be a vast number of parallel processes going on in every living brain in every single second. All they knew of and understood was the final output that reaches the conscious part of the brain, which can be even extremely restricted at times.
We have inherited from the tens of thousands of generations of our ancestors a vast number of reflexes, models of behavior and trains of thought that affect our life every single second we live. There is also an extremely complex collection of social brain-processes that fire up in the brain when we mix with our fellow humans. There is always a biological base for these things also, but these processes are also changed by evolution of the human culture.

However, we are not normally aware of their presence on a conscious level. They just inevitably change the way we see our environment and most of how we see all different social situations. On top of all this we slowly build an individual psyche. It is always different from that of anybody else who has ever lived. This psyche is a molded by all good, bad and irrelevant things that happen to us.
Of course, this individuality rests on a very strong base of inherited traits and features. However, our individual life-experiences will always produce a different end-result for every single human. Let me repeat: explaining all this just with a concept of ‘mind’ is simply reductionism at its worst.

There are also inherited traits and brain-processes that different cultures have learned to use to reach new ends. For example, the brain functions that handle speech have according to some theories been developed further by development of music, which still touches the raw emotion-systems in the brain through this channel.
Language itself was developed to use these brain-processes when one species of the great apes learned to use sounds in dramatically new functions. The fact that several people can with the use of language share the contents of their brain with other people is unique to humans. As far as we know, the human species is the only one that has developed a complex enough language to convey even the most abstract contents of their brain to other members of their species.

The invention of language did also change the way how humans themselves think that they use their brain. They normally see just the end-result which is formulated as language. The very basic processing of raw information happens as it happens in other animals, also without language. We just are not aware of these underlying processes, because they now feed their results in the form of language to the conscious part of the brain.
Subconscious part of the mind does not work independent of you, as it IS you. It holds all of your experiences, hopes, dreams and ideas. Subconsciousness stores our life and uses it as a tool to inspect and analyze all of new things that we encounter. The results of this process are then processed in the conscious mind.

The conscious part of our mind, however, makes all the decisions. On the other hand, in very fast situations we must rely on the gut-reaction or the results of only pre-processed information that has not been checked in the conscious part of the mind. This is one of the reasons why fast decisions are so often faulty.
The slow conscious processing of data on a conscious level does give better results in many cases. The subconscious part moves more on the level of emotions, feelings and using old examples for new action. Conscious part of the mind adds reasoning and rational analysis to the picture. The development of language-using machinery into our mind has given us the possibility for logic and rational reasoning.

These qualities are of course also the things that made possible all human inventions. This development of a language-based conscious mind is the very basic thing that separated humans from other animals. It also gave humans this tremendous advantage over all other animals that we now enjoy.
Human brain was already a very complex organ at the time when we parted ways with the other great apes. However, mainly the development of language has created an incredible explosion in the complexity in the ways of how the human brain can work.

No other species has undergone such a transformation as the birth of language did cause in human species. However, under all this complexity there is still the third species of chimpanzee. They just try to control also their natural impulses and emotions with this newly perfected brain of theirs.
The human brain started seriously diverging from the brain of a dog or a cat with the birth of language. It becomes possible nearly immortalize some contents of the brain with the invention of writing.

Only the birth of language made it possible also to develop abstract ideas like the ‘mind'. The development of the human brain has been a process that has taken an incredibly long time. The development of the first nerve cell was naturally the very first step that was followed by the development of the nervous system and finally the first precursors of brain.
An extremely hard question is at which point of evolution did animals become fully conscious of themselves. Most of all it is hard to define at which particular point of human evolution did humans develop something that can be called a 'mind’ as this idea is commonly now understood. Even amoeba knows where it ends and other amoeba starts. There still is no definite answer to this question. The whole thing depends on how you define ‘mind’ and many traditionalists are prone to claim that only humans can have a ‘mind’.

Albrecht Durer, Lions sketch. Circa 1520 - Wikipedia

Lions make conscious decisions when they choose a suitable prey from a flock of antelopes. A lion looks for certain signals that may make some of the prey easier targets than other. Then it makes a conscious decision that is based on the information it has obtained, just like humans do. The difference is that this decision is made without expressing it in language in lions.
The big step that humans did take was not development of a ‘mind’, but just the new ability to express its existence through the use of language. It has been established without doubt that all mammals do share a very similar basic brain-structure with humans. It is quite certain that they all also have a very similar vast collections of brain-processes that are called ‘mind’ in humans for reasons of simplicity and tradition. The only real difference is that other mammals just can’t express themselves in a language that we could at least yet interpret.

On a little lighter note, I personally believe in ‘minds’ that exist outside the brain. I have hundreds and hundreds of them stacked on shelves of my book-case. The invention of writing made it possible to preserve some of the contents of a human brain permanently.
Every book is a little window to the contents of the brain of its writer. Some of course tell very little of the true thought of the writer, but some great books can act as true gates to another human mind. When I press these little buttons to produce symbols on this screen to be transported over the vast oceans to my friends in Philippines or America, I am, in fact, extending my brain to reach other people. Boggles the mind, sometimes.

The study of how the human brain works has seen a fantastic rise in knowledge. We know immensely more of every single facet and function of the brain than we did 50 or even ten years ago. Neurobiology, neurology and all other fields of research of the brain and mind have advanced in bounds and leaps. We have seen an amazing rise in understanding how our brain works in a very few years with the coming of magnetic resonance imaging (MRI) and other techniques.

Added 31.1.2012; Julian Baggini must have been reading this blog......

Similar rise in understanding is sadly lacking in philosophy. It remains all too often often stuck in the old trenches that were dug ages ago. So, if you want to know and understand more how human brain or ‘mind’ works, you nowadays won't find help in philosophy at all, but in science.
One of the main reasons for this apparent lack of development is the strange ancient belief in immortality of some kind of 'soul' or 'mind'. This idea has made also many philosophers supportive to ideas that would make it possible to retain this ancient belief.

This belief is, of course, an old one. According to some anthropologists it is based on the fact that the memory of a dead person persists in our mind as if he would be still alive in our minds. On the other hand, the written word has made it possible to preserve the contents of the human mind and make it 'immortal'.
On the other hand, if you believe in a thing like immortal soul, you need to first renounce evolution. If you believe that a 'soul' is a purely human property, you need to believe that humans have existed always just as they are, or you end up in trouble.

The very first mammals were rat-sized four-legged creatures. Did they have a 'soul' that was reborn in other little mammals? If you resolve that hurdle, in the end you need to go all the way and to decide if also the first one-cell creatures also had a 'soul' or was just the idea of a ‘soul’ developed with the birth of the spoken language?
The answer is inevitably the latter. The idea of a ‘soul’ is a similar attempt to simplify a complex issue as the idea of a ‘mind’ is.

One thought still; the idea of reincarnation was quite natural one in the times when there was no idea of genes and genetics. Suddenly there just was this spitting image of the demised uncle as the new nephew.
Nobody knew how different features pass differently and can jump over generations and so on. The idea of reincarnation was just an easy way out of a problem. The sorry fact is that the less you know about biology, the easier it is to retain these ancient beliefs, and the more you know, the more difficult it becomes.

However, in fields like biology and scientific research of the brain and human cognition there are things that we can be even extremely certain of. Of course, we learn more all the time. This new knowledge will inevitably always change also the existing ideas that are stored in the brain.
During the whole recent explosion in our knowledge of how the human mind works, there has never been presented new scientific ideas or findings that would in any way support the alleged separateness of the ‘mind’ and brain.

On the contrary, it has become possible to explain processes and features that were quite in-explainable a few decades ago. In fact, we start to understand now how all of the main function of the brain like emotions, thoughts, reflexes are created and handled in the brain.
There still are these old belief-systems whose followers want so dearly to believe that an invisible part of a human does not die at the death of his body. They are ready desperately to grab any idea that would allow them to retain their belief in that the mind is somehow separate from the brain.
However, no reliable evidence of any such thing has ever been presented. When the brain dies permanently, your brain and your ‘mind’ do cease to function and in practice cease to exist, even if your body is kept going artificially.

PS. This little essay is based largely on work done by Steven Pinker. However, there are also dozens of lectures, articles and books by many other people working in the field of studying of the human mind that have had an influence.

(This piece was extended and totally refurbished at 22th of January, 2012 and it was refurbished again on 17th of April, 2013)