The theory of evolution is an explanation for the development of life on Earth through natural processes. The concept dates back to the ancient Greeks and was re-popularized in modern times by an English naturalist, Charles Darwin (1809-1882). he suggested that all living things reached their present form by gradual change or evolution. The basic idea behind the theory of evolution is that all the different species have evolved from simple life forms, which first developed more than 3 billion years ago. The basic idea behind the theory of evolution is that all the different species have evolved from simple life forms, which first developed more than 3billion years ago. The tiger's stripes are really the animal's adaptation to its environment - its camouflage, which served to protect them. This adaptation occurred over millions of years of evolution.

According to Darwin's theory, in the process of evolution, a change occurs in an organism due to radiation, chemicals, or by chance. This change is either retained or removed by natural selection, which is a process of survival of the fittest. If the organism survives, it passes its traits on to its offspring. Over time, these changes accumulate in the population and another species evolves, which is totally different from its ancestors.

The concept of 'survival of the fittest ' is based on the following:

Life on Earth is believed to have originated about 3.9 to 3.5 billion years ago, in the form of microbes. Also called microorganisms, these single-celled forms include bacteria, fungi, archaea, and Protista, and can survive in extreme temperatures, acidity, salinity, or alkalinity. It took several billion years for bacteria to evolve into Cyanobacteria, also called 'blue-green algae', which are the ancestors of all living plants and animals.

By the study of fossils and from the analysis of similarities and differences in the DNA of organisms, it has been found that the first living thing developed by the natural conditions on Earth at the time of its formation. Studies on biological evolutions suggest that simple living organisms evolved into complex ones through the process of self-transformation. According to this theory, humans have evolved from primates.

Living organisms or beings are forms that can grow, breathe, respond to stimuli, reproduce and adapt to their environment. An individual living being such as a plant, animal, bacterium, fungus, or a human being, has a body made up of organs that work together to carry on the various processes of life.

All terrestrial life-forms (with the exception of viruses) are divided into several kingdoms. Each kingdom is further divided into phyla, classes, orders, families, genera, and species. The five major kingdoms of life are:

Approximately 10,000 species; unicellular and colonial; including eubacteria and blue-green algae.

Approx. 250,000 species; unicellular protozoans and unicellular & multicellular algae.

Approx. 100,000 species; multicellular; having a single set of chromosomes.

Approximately 250,000 species; retaining embryos within female sex organs on the parent plant.

1,000,000 species; multicellular, without cell walls, and without photosynthetic pigments.

DNA - Deoxyribonucleic acid - is a long linear compound found in the nucleus of a cell of nearly all living organisms. It contains the genetic information used in the development and functioning of all known living organisms. Living beings must have a program to make copies of themselves from generation to generation. This program of life is encoded in their DNA.