The Brain and the Human Condition

While many may see this discussion as tangential, and possibly irrelevant to the political debate, if politics is a human activity, then the workings of our brains is at the very centre of this debate. As a species, humanity has classed itself to be Homo Sapien, even though our collective wisdom might often be questioned. However, within the evolutionary tree of life, our intellectual capacity to manipulate our environment appears to suggest that humanity stands apart from any other life-forms on planet Earth. Yet, despite all the apparent differences to the rest of the animal kingdom, we still share 99% of our DNA with several species of great ape.

So what makes us human?

It is not unreasonable to assume that the evolutionary increase in brain size must have some direct correlation to our intellectual capacity to solve problems, which first helped us to adapt to new environments and then to eventually manipulate the environment to best meet our survival needs. Over a period of some seven million years, the human brain has tripled in size, although most of this growth has occurred in the last two million years. In part, this increase in brain size is often explained in terms of both environmental and dietary changes forced on earlier hominids, which in-turn may have led to changes in the complexity of social groupings in order to survive. However, the development of larger brains came with many negative survival risks, which natural selection would not necessarily consider sustainable unless it ultimately led to increase survival rates. To counter this negative aspect, it seems that that an increased brain size also triggered the need for more complex social groupings in order to ensure the survival of infants, whose brains now required many years to fully develop.

OK, so how big is the human brain?

The adult human brain is estimated to have average volume around 1200cm3 with an average weight of about 1.5kg. However, such macroscopic details do not come close to quantifying the complexity of the human brain, which consists of billions of neurons with about 10-50 times that number of other cells, which serve to support and protect the neurons. While such numbers appear enormous, the actual complexity of the brain can only be fully appreciated when accounting for the fact that each of the billions of neurons may form thousands of connections to another neurons, which gives rise to a neural network of cells in the order of 100 trillion (1014). So, somewhere in this vast interconnectivity of cells, the idea of human consciousness came into existence along with an ability to make logical choices subject to all the emotional inconsistencies, which we have labelled in terms of the human condition.

OK, but do we have any idea how these 100 trillion neurons get wired up?

The actual structural evolution of the human brain extends back along a timeline measured in hundreds of millions of years, when intelligence was limited to very basic survival instincts. While many of these survival instincts are still encoded into our DNA, they have also been augmented by millions of years of subsequent evolution that has extended the human ability for logical thoughts, even though our actions can still be influenced by emotional behaviour. While the model below, known as the 'Triune Brain', is no longer considered mainstream, it possibly serves a useful purpose within this overview in that it suggests a basic framework in which the evolution of the human brain has progressed.

The oldest part of the brain, which is comprised of the brain stem and the cerebellum is labelled the Reptile Brain as it is responsible for the most basic behavioural traits, i.e. survival instincts and direct stimulus responses encompassing fight-or-flight. Today, modern brain research is beginning understand that much human behaviour, e.g. reflex action, is still controlled by essentially unconscious thought processes in the brain stem because there is not enough time for higher conscious thought to process the information from our senses. The next development along the evolutionary timeline is labelled the Mammal Brain that sits above the brain stem and cerebellum and consists of the hippocampus, hypothalamus and amygdala. One of the functions of this component of the brain is to both generate and regulate the flow of key chemicals, which helps control our memory and emotions, and underpins many other behavioural traits. These evolutionary extensions are generally lacking in reptiles, but present in mammals and in higher primates, where the limbic system is described as acting as a buffer between our thoughts and actions. By way of a generalised example, we might realise that without any ability for emotional empathy, we might act in very inhuman ways to others to the point that we might be described as sociopaths. The final and most recent evolution of the brain is known as the Human Brain as its structure is essentially unique to humanity. As such, the neocortex is part of the brain that we associated with conscious thought, which is responsible for much of what we think makes us human, e.g. logic, reason, art, music, science, creativity, language.

Given its importance, what else do we know about the neocortex?

As a generalisation, the neocortex is often described as being divided into four major lobes: frontal, parietal, temporal and occipital, where the pictures below simply gives an indication of the real structural complexity involved, which is way beyond the needs of this discussion.

So, in summary, the neocortex might simply be described as being structurally divided into two halves. The left hemisphere is responsible for the capability to engage in analytical thought, verbal and written communication plus logic and reason in the form of mathematic and scientific thought. In contrast, the right hemisphere makes different types of activities and traits possible, such as intuition, empathy, creative expression, art, music, and holistic thought. While these two halves have to work in some form of balance, this is not always the case and an imbalance towards one brain hemisphere or the other can lead to many forms of dysfunctional behaviour.

Note: It is estimated that 1-in-4 people in the world will be affected by mental or neurological disorders at some point in their lives. At any time, around 450 million people worldwide are thought to suffer from such conditions, placing mental disorders among the leading causes of ill-health and disability. However, it is not clear that this estimate really accounts for all other behavioural problems observed in many societies around the world associated with stress and alcohol/drug abuse. Equally, based on standard IQ score distribution, approximately 10-15% of any population might be classed as mentally retarded, although such a stark statement might now been seen as political incorrect. However, the fact remains that a significant percentage of any democratic majority may not be fully rational in the choices it makes.

However, it should also be mentioned that the human brain does not come fully form at birth, although it possesses all the billions of neurons it will ever have. As already outlined, the brain processes information by forming networks of neurons, which communicate via electrical and chemical signals, which ultimately form the basis of learning and memory. However, this system of neutron interconnectivity and communication takes a long time to develop between birth and adolescence. So, while a baby, at birth, already has all of the neurons it will ever have, the brain as a whole doubles in size during the first year and by age three, it will have reached ~80% of its adult volume. However, more importantly, the interconnectivity between neurons form at a faster rate during these years than at any other time and by the age two or three, the brain has up to twice as many synapses as it will have in adulthood, as suggested by the following diagram:

How does neuroscience explain this process?

It would seem that this process is dependent on both genetic and environmental factors, which might be characterised in terms of the more widely understood processes of 'nature versus nurture' and the expression of 'use it or lose it'. In the earliest stages, brain development is primarily affected by genetic factors, although environmental and dietary factors surrounding foetal development can also be key factors. However, it is our DNA, in the form of genes, which direct the developing neurons to form all the necessary parts of the brain in accordance to an individuals DNA blueprint, although coherence of the signalling within the neural network is far from complete. After birth, the brain starts to 'wire' itself in response to the inputs it receives from its surrounding environment, i.e. via its senses and experiences, to which the excess of connections in the childhood brain makes it more responsive. This ability of the brain to, in part, shape itself is called 'plasticity' and has allowed humanity to adapt more quickly to environmental change than our basic DNA blueprint would allow. For example, speech sounds that stimulate activity in language-related brain regions, pre-exist based on the DNA blueprint, but are not fully wired until the brain starts to use them. As a consequence, neural pathways that rarely get used remain weak and may eventually be pruned away during adolescence, such that nurture can not only determine what information enters the brain, but may also influence how the brain ultimately processes information.

OK, while this may be interesting to some, what has it really got to do with politics?

Whether we accept it or not, how we act as rational human beings depends on the internal wiring of our brains. In addition, the 1.5kg of grey matter in which we perceive and process existence has undergone millions of years of evolution, apparently guided by just one overriding goal: survival. However, somewhere long this evolutionary path, the emergence of conscious free-will and logical thought appeared, although our human brain still retains many aspects of an earlier mammal brain and reptile brain. Research also suggests that the development of the human brain through childhood can be critical to how we come to see the world and that the formation of this complexity can lead to many forms of dysfunctional behaviour, which may impair our ability to act rationally. If so, the one of the biggest obstacles standing in the way of progress may be ourselves.