There are some changes that we cannot see easily with our eyes easily. Many species of organisms are born on earth. These changes take a long time than a human life to be seen. Therefore, humans cannot see the sequence of development of these changes. But scientists have collected many proofs and facts to prove these changes.
Many types of organisms and their species (some of them are alive) and some of them have evolved through organic development.
Development of Life
Development means change. Development is the changes from which new species of organisms are developed. New species take time to develop. The situations of earth are constantly changing. Therefore, it is necessary to adapt with these changes. These changes are necessary with the situations. The species which are unable to coordinate with these changes die and get extinct, for example - dinosaur. All new species originate from their predecessors.
Charles Darwin (1809-1822) was a great scientist. He collected many logics and said two important things for development.
- All the specie organisms originate from the development process.
- All the process of biological development is called natural selection of spices.
This means that all natural organisms choose and reproduce such organisms that are adaptable to environment.
One Living Cell Organism to Multi Cell Organism
The physical conditions of earth are changing and this has lead to many developmental changes in organisms. There were many changes in the development process which has lead to the development of many species and organisms. The process of development for biological process is considered to be natural selection.
The earth was not there before billion years. Slowly, natural changes came into place and the earth became around 4-5 billion years ago. There are many stages of development:
First stage: there was no water on earth, clouds only thundered. However, slowly temperature declines, started raining and water was collected on earth. There was no organism till date.
Second stage: first of all very small micro organisms evolved in water. These are the predecessors of every organism now days. There one branch of bacteria is also seen today, there was no open oxygen in atmosphere in this stage.
Third stage: single cell organisms went through many changes and the process of photosynthesis became possible. Oxygen increased in the atmosphere. Many kinds of organisms took birth. After micro organisms, Algae came into existence which is found in ponds and single cell protozoa were also born. Due to development of changes in single cell predecessor, many single cell organisms like fungi, plants and humans were also developed.
Dinosaurs and their Extinction
Changes in development process are not seen in common, but many facts suggest that organisms have evolved from development. Fossils are also such facts. Fossils are the remains of those organisms which were present on earth before. These are found after digging mountains or stones. The bodies of many organisms take the shape of stone after a time period.
Many huge dinosaurs used to live on earth around 15 crore years ago. There was no bird or mammals on the earth at that time. Many fossils of dinosaurs have been found after digging of the earth. They belong to reptiles group of animals. Now a days lizard, snakes, tortoise and crocodile come in this category.
There were many species of dinosaurs, some use to live in water, some could fly in air and some could walk on land. Dinosaurs used to rile earth 230 lakh year ago to 65 lakh years ago. Some used to eat plants and some were carnivores.
A big lizard is found in Comodo Island in the Pacific Ocean and represents dinosaur. It is called Commodo Dragon.
Dinosaurs were living a happy life on earth at that time, slowly the environment on earth changed. Some scientists believe that due to spreading of a specific radiation all dinosaurs died and got extinct.
Development is Still Going
Humans evolved on earth around 20 lakh years back. Humans have many ancient features but it is most complex and high level of development that took place because of maximum development of human mind. Human body is going through change but these changes are very micro, human development is going and still is going.
Humans are considered similar to ape (like chimpanzee).