How does human brain function? Human brain is the most important, complex and incredible part of human body which is responsible for controlling most of our routine functions, which include breathing, sleeping and body temperature; thinking and feeling and; sensing and moving.  The human brain provides us with the awareness of space, time and environment by processing billions of bits of information. It process information coming from our senses and helps store and retrieve that information from our short term and long term memory. Let’s understand the evolution, physiology and functioning of human brain.

Evolution and Human brain

From an evolutionary perspective human brain is the most evolved form of brain which started developing from few neurons billions of years ago and transformed into reptilian and mammalian brain before becoming human brain. From an evolutionary viewpoint human brain has evolved over hundreds of millions of years from primitive reptilian brain, to complex and sophisticated human brain. Let’s understand reptilian, mammalian and human constituents of brain separately.

Reptilian Brain

Reptilian brain is about 300 to 500 million years old. It is responsible for the very fundamental functions necessary for survival like breathing, heart rate, body temperature, sleep, digestion, posture and balance. The brain stem and the cerebellum parts of the human brain comprises of reptilian brain. These structures are major components of any reptiles’ brain.

Mammalian Brain

Mammalian brain is about 100 to 200 million years old and termed as limbic brain. It is primarily responsible for the experience of emotions. It is also responsible for recording memories, attention, sensation and hormone secretion. Mammalian brain comprises of limbic system which in turn comprises of thalamus, hypothalamus, hippocampus and amygdala.

Human Brain

Human brain is about 3 to 5 million years old and is termed as neocortex brain. It is responsible for the development of logic, reasoning, language, abstract thought, imagination and creativity. It consists of two hemispheres; right and left hemisphere.


Human Brain: Anatomy and Functions

Anatomically, human brain comprises of four regions: cerebrum, cerebellum, limbic system and brainstem. Let’s analyze the functions of these four major brain regions separately.


Cerebrum comprises of corpus callosum, two hemispheres (right and left), and each hemisphere consists of four lobes. Four lobes are termed as frontal lobes, parietal lobes, temporal lobes and occipital lobes. Frontal lobes are responsible for attention, intellect, creative thinking, judgement, reflection, planning, speech, problem solving, and motor function. Parietal lobes are responsible for spatial and visual perception, interpreting language and managing sensations. Temporal lobes deal with memory, hearing, speech, organization and language understanding. Occipital lobes contain visual processing system of brain. It interprets the visual information sent by the eyes. Corpus callosum is responsible for the communication between left and right hemispheres. Right hemisphere controls the left side of body and is related to creativity, artistic ability and visual and spatial ability. Left hemisphere is related to comprehension, arithmetic, speech and writing.

Limbic system

Limbic system comprises of thalamus, hypothalamus, amygdala and hippocampus. Let’s analyze each component separately.

Hypothalamus is responsible for controlling hunger, thirst, sleep, moods, sexual response and regulates body temperature and blood pressure. It also regulates emotions and hormones secretion. It controls autonomic nervous system, circadian rhythms and homeostasis. It also controls pituitary gland which is responsible for secretion of hormones which control growth, thyroid glands, sexual maturation, sexual functioning, pregnancy, child birth, temperature regulation. Pituitary gland also responds to stress, pain and fight disease.

Amygdala responds to emotions, memory and fear.

Hippocampus is responsible for learning and memory building. It converts short term memory into long term memory. It is also important for remembering, recalling and analyzing spatial relationships.

Thalamus is responsible for alertness, attentions, memory and sensation.


Cerebellum is responsible for coordinating and regulating muscle movements, posture and balance. It receives information from body muscles and use this information to maintain body balance and posture, and controls the timing of complex motor actions such as writing and walking.


Brainstem performs many automatic functions such as, breathing, heart rate, body temperature, wake and sleep cycles, digestion, vomiting, swallowing, coughing and sneezing.

 What makes us Human?

Human brain which evolved from reptilian and mammalian brain provides us with the ability to perform higher order functions like, Logic and reasoning; Abstract thinking; Planning and problem solving; imagination and creativity and; Language and culture. Therefore, arguably this unique and complex human brain which allows us to perform these higher order functions, which in turn distinguish us from other species, makes us human.