EVOLUTION OF LIFE ON EARTH

About 4600 million years ago, the planet earth was formed from dust and gas. It was full of poisonous gases with no food to eat and hence with no living things. It seems as per theory, that every living thing came out of a common ancestor that lived long ago. Though living things have different genes, they have all inherited the same genetic code to make those genes work.
Evolution is a theory that living things change from generation to generation with a change in the genetic composition with time and change in climatic conditions. The ingredients in the formation of life are water, carbon dioxide, methane and ammonia. Lighting or ultraviolet radiation might have changed these chemicals into amino acids, which are the building blocks of proteins, which constitute living things, mainly. Evolution theory was first given by Charles Darwin and others in 1850s. According to Darwinsm, the natural selection is the mechanism of evolution. Living things slowly changed and evolved into different species over millions of years.
About 3800 million years ago, first life appeared consisting of primitive single-celled organisms. 3300 million years back, the first simple plants, algae apeared in oceans. About 700 million years ago first water animals such as worms, jelly fish (multicellular animals) appeared. 450 million years back first fish (first vertebrate) appeared in the oceans. 410 million years ago first plants appeared on land. About 230 million years back early dinosaurs moved on earth. 60 million years ago the first large mammals emerged. About 14 million years ago, early apes appeared. During the period of 10000 years to 1.8 million years back, early modern man emerged in Africa.
No one has seen prehistoric animals such as dinosaurs. But we know about them sufficiently from their fossils, resulting from their bones burried in mud or sand million years ago and then turned to rock by natural chemical process.
A large part of life cannot be seen with naked eye. It can only be viewed through a microscope. Besides plants, animals and bacteria, fungi (mushrooms and toadstools) is another type of life, looking like plants, but grow by absorbing food instead of by using sunlight.
All living things are connected to each other. Plants get energy from sunlight. Animals eat these plants as their livelihood. Some animals eat each other and live. When animals and plants die, bacteria and fungi break them down. And recycling starts. This process is ecology.