The human nervous system is a complex internal network that allows a person to 'sense' its environment. The network includes sensory components that detect changes in the environment and motor components that help generate physical movement, contract cardiac muscles and initiate glandular secretions. Collectively, the nervous system receives, stores and processes sensory information and then coordinates the appropriate motor response.. The nervous system comprises of two divisions:
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
The former includes the brain and spinal cord, while the latter includes the sensory receptors, sensory nerves and ganglia. A further division can also be made between the sensory and motor components of the nervous system. The sensory components bring information into the nervous system, which is ultimately channelled to the higher levels of the cerebral cortex. In contrast, the motor components carry information out of the nervous system resulting in muscle contractions or various glandular secretions. The hemispheres of the brain consist of the cerebral cortex and three nuclei called the basal ganglia, hippocampus and amygdala. The functions of the cerebral hemispheres are perception, higher motor functions, cognition, memory and emotions. The cerebral cortex consists of four lobes called:
- Frontal Lobes
- Parietal Lobes
- Temporal Lobes
- Occipital Lobes
Again, the evidence suggests that the human brain has evolved as an effective network of cells and nerves with specific functions that helped meet the challenges of survival. Research has shown that many of the major neural systems present in man are also present in most mammals; therefore it would appear that the basic neural functions have evolved over a very long period of time, e.g. millions of years.
- Senses allow both the sensation and detection of events in the
iv) Olfaction (smell)
- Basic instincts and emotions:
ii) Love, lust and sex
iii) Anger, hate & fear
iv) Territoriality, possessiveness
v) Dominance, submissiveness
vi) Irritability and serenity.
vii) Social, parenting & family ties
- Cognitive capabilities:
i) Arousal, Attention,
ii) Thinking, Evaluating, Insight,
iii) Abstraction, Creativity,
iv) Choice, Purpose,
v) Seeking, Planning, Generalization,
vi) Judgement, Introspection, Programming,
vii) Interest, Preference, Discrimination,
viii) Learning, Memory, Recognition, Retention, Knowledge.
- Basic behavioural repertoire:
i) Reflexes & Basic Action sequences
ii) Instincts; integrated action sequences
iii) Learned action sequences.
iv) Play & Exploratory behaviour
v) Goal Directed behaviours
The evidence suggests that it has taken life a long time to evolve all the functions that now help humanity to survive in such a broad and diverse range of environments. In this context, intelligence and self-awareness may only have been an accidental by-product of the survival process.