Charles Darwin’s Theory of Evolution, first published in 1859, showed how all species of plant and animal adapt and develop over millions of years.
Darwin’s theory depended on the fact that no two living things are alike.
Some animals start life with characteristics that give them a better chance of surviving to pass the characteristics on to their offspring.
Other animals’ characteristics mean that they are less likely to survive.
Over many generations and thousands of years, better-adapted animals and plants survive and flourish, while others die out or find a new home.
Fossil discoveries since Darwin’s time have supported his theory, and lines of evolution can be traced for thousands of species.
Fossils also show that evolution is not always as slow and steady as Darwin thought. Some scientists believe change comes in rapid bursts, separated by long slow periods when little changes. Other scientists believe that bursts of rapid change interrupt periods of long steady change.
For the first 3 billion years of Earth’s history, the only life forms were microscopic, single-celled, marine (sea) organisms such as bacteria and amoeba. Sponges and jellyfish, the first multi-celled creatures, appeared by 7(H) million years ago (mya).
About 600 mya, evolution speeded up dramatically in what is called the Precambrian explosion. Thousands of different organisms appeared within a very short period of time, including the first proper animals with bones a nd shells.
After the Precambrian era, life evolved rapidly. Fish developed, then insects ,Ind then, about 380 mya, amphibians, which were the first large creatures to crawl on land. About 340 mya, reptiles evolved – the first large creatures to live entirely on land.
Dinosaurs developed from these early reptiles about 220 mya and dominated I lie Earth for 160 million years. Birds also evolved from the reptiles, and ynodonts furry, mammal-like creatures.