How did evolution of humans occurred?

According to information obtained from various fields of science, the origin of all living things on our planet is the same. This ancestor was a single cell and came into being some four billion years ago today. How did millions of different species come into being from this single-celled organism? The theory of evolution answers this question.

Some people, without studying the theory of evolution, assume that man was the first ape according to this theory. In other words, monkeys evolved into humans. Then they ask why there are monkeys? Why didn't they all evolve and become human? This is a misunderstanding. The theory of evolution does not claim that apes are human. However, it has been proved that the source or ancestor of all living beings was one.

Organisms produce offspring through sexual intercourse and pass on their genes or traits to offspring. These features also change slightly during the transfer. As a result of these changes, which have taken place over millions of millions of years, a different kind of animal has finally come into being. These changes are the result of mutations or alterations in DNA. Every living cell has its own DNA.

It can also be called blueprint or building block. It is actually a chain-like chemical code that directs the cell to grow and perform its function. DNA is part of the chromosome that is found in the center of the cell in the form of pairs. Each human cell has 23 pairs of chromosomes or 46 chromosomes. Twenty-two pairs are numbered from 1 to 22. The 23rd pair is called XY in males and XX in females.

This chromosome determines the sex of a human being (male or female). During the process of cell division, the DNA of the cell is also copied which is received by the new cell. DNA mutations are caused by copying errors (additions, subtractions, substitutions).

These errors are sometimes merciful, sometimes painful, and sometimes harmless.
Examples of mercy are changes in DNA that strengthen the human immune system to fight viruses and germs. These changes also increase a person's ability to adapt to changing environments. An example of a problem is the changes that cause hereditary diseases in children. An example of harmless change is the blue eyes of humans.

Errors or alterations in the DNA of an organism during the process of copying continue for millions of years, resulting in the organism becoming a new species. Four billion years ago, there was only single-celled living thing on earth. As a result of mutations in DNA, multicellular organisms gradually came into being. Then, from these multicellular organisms, more complex organisms emerged. In other words, life began with the simplest single-celled organism, and then gradually evolved into more complex organisms. Human is one of these living beings.

Life on Earth began about four and a half billion years ago with the birth of a single cell. Then, through the process of evolution, multicellular organisms came into being. Like the atom of an element, every cell in an organism has DNA in its center, which can be called a blueprint or construction plan of that organism. If this DNA continues to change over millions of years, then a new kind of living thing comes into being. That is evolution.

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References:

1- https://www.healio.com/hematology-oncology/learn-genomics/genomics-primer/what-are-chromosomes

2- https://en.wikipedia.org/wiki/History_of_life