What is evolution?
Evolution refers to the orderly and gradual biological changes across generations. Our ancestors evolved from the time of chimpanzees. Famous and widely accepted Charles Darwin’s theory of natural selection talked about how the survival of the fittest and show’s which species is going to continue and what features of behavior biological as well as emotional is going to continue in the future.
Milestones in human evolution
Basically, three major changes occurred in humans. First is a straight posture that humans have the chimpanzee is used to have a stooped posture which kept on becoming straight over the generations so now humans have a straight posture. The second is the brain structure as well as the brain size.
Now average human brain size is much larger than the rest of the bodyweight and compared to other species. The brain has a lot of structures within it so that is one major feature along with that in the brain itself our cerebral hemisphere.
It is one of the biggest and the most important ones in humans but in animals it’s a very small portion of it of the brain and less important but for humans, it’s the most develop and that is why human species are considered to be the most intelligent in the world.
The third feature is the use of a refined thumb that is the third major important feature that’s about the concept of evolution. Humans gradually adopting and modifying the environment according to need. Now, whatever features were important for us based on our survival have been continued in our genetic structures and we have imbibed the best of it all.
Biological basis of behavior
In our brain specialized nerve cells which are very unique and we have around 12 billion nerve cells or neurons in our brain now every neuron is empowered to get information from outside stimuli through the sense organs reach the brain cell and from that brain cell transmits itself to the rest of the nervous system.
It can be to one neuron the one which is required for that action it could also be to a number of neurons and that is like an interconnected network that the brain has an interconnected set of neurons now every neuron has three major components and it also has electrical activity as well as a chemical activity.
When we touch a hot object that’ll be a simple reflex action that will not require any brain but if when we solve a math problem in In that case a stimulus from outside has energy and that information passes on to the brain and the neuron basically will be starting on with the nerve receptors which are the beginning part of the neuron called the dendrites.
These are the tree-like structures which receive the information from the stimulus now once they receive the information it passes on to the soma which is the cell body now this cell body also has the nucleus for processing and synthesizing the protein and the reproduction of the cells from the soma or the center the cell of the body the information pass on to a thread-like structure which is known as the axon.
Now this is a rope-like structure once the information starts off it will not stop till the time it has reached its final destination either the information will not start the neurons will not fire or the nerve potential will not start itself if the stimulus energy is weak but if the stimulus energy is appropriate and optimal once the neurons have started firing it will reach its final destination.
This principle is known as all-or-none principle. So once a neuron starts it goes on till the end that is the all-or-none principle. Once the information has reached the central part this information travels through the strength or the length of the axon and reaches towards the end the end is known as the axon terminal or the axon point.
The axon tip is also known as the terminal button and it has chemicals stored in it. Once the nerve impulse (which has the electrical part) has reached the terminal buttons the chemicals stored in the terminal button is known as a neurotransmitter it will be released into a gap.
Every neuron has a gap between which called the synaptic cleft. Here the chemical will be released. This chemical ensures behavior if someone over-anxious it’s because of this chemical. Laziness also because of the brain chemical being released in this particular synaptic cleft.
Different kind of nerves
Two major kinds of nerves sensory nerves and motor nerves. The sensory nerves basically are known as afferent nerves and the major function of these is to transmit information from the outside environment. After the information has reached the brain it will be processed after the processing there will be an action outside of the stimulus so this action will be from the motor nerve.
The glands in the muscles to the outside environment is known as efferent nerves. These nerves ensure that all the decisions are taken appropriately because once the information is taken on from the sense organ from the outside environment from the stimuli that information travels on through the sense organs reaches the brain processed.
A decision was taken through the glands and the muscles there’s an outside action. The human brain it’s a very sophisticated system. It’s an automatic system that is working. If the brain is functioning well the whole body is functioning because every system the body is coordinated through the brain.
Types of the nervous system
The nervous system basically has two major parts one part is known as the peripheral nervous system the other part is known as the central nervous system. The central nervous system comprises two major parts the brain and the spinal cord whereas the peripheral system comprises the majorly somatic nervous system and autonomic nervous system.
Peripheral nervous system: It deals with the major nerves except that of the brain and the spinal cord. Somatic nerves are thirty-one in number thirty-one sets having the mixed sensory and motor nerves.
Cranial nerves which are 15 in number these cranial nerves also have a similar function to the sensory neurons and motor neurons and the mixed neurons. They transmit information from the rest of the body.
Somatic nerves and the cranial nerves only work with the head region so the information which is sensory or motor is only dealt with by the cranial nerves of the head whereas the somatic nerves deal with all over the body except the brain and the spinal cord.
Autonomic nervous system: The second part of the peripheral nervous system. All the nerves in the body which transmit information and pass on the information to the brain. Autonomic which is a very important part of the brain and that deals with the aspect of involuntary functions all the functions which are life-supporting functions like blood pressure heartbeat which are functioning on their own.
Fight or flight response: When we are stressed out two major parts, one is the sympathetic nervous system which is the emergency or the crisis intervention center. all the major body parts which have to take an action like muscles are activated all the blood is flowing from the stomach to the muscles and that’s why the major organs start functioning actively like the heart starts beating a faster tear gland are activated salivation is inhibited sweating starts off.
All these ensure that the action is taken it’s a fight-or-flight reaction. Humans either deal with it. Adrenaline hormone is released to fight it out or to run away from that situation.
When this situation is over the body has to calm down and the parasympathetic nervous system takes over this system. It is relaxing, resting, and digesting part. Stomach function the digestive function can go back to normal the blood is restored back into the stomach.