Evolution

Evolution is the process through which living things change and develop over many generations. It explains how all forms of life on earth—plants, animals, and microorganisms—are related and how they have changed since life first appeared billions of years ago. Evolution helps scientists understand the variety of living things, or biodiversity, that exists today.

The main idea of evolution is that all living things share common ancestors. This means that, long ago, very simple forms of life slowly changed into more complex ones. Over time, small changes built up, leading to the many species we see now. For example, scientists believe that birds and reptiles share ancient ancestors, and that whales evolved from land animals that returned to the sea.

Evolution happens because of genetic variation and natural selection. Genetic variation means that individuals in a species are not exactly alike—they have small differences in their genes. These differences can affect how well they survive and reproduce. Natural selection is the process where organisms with traits that help them live better in their environment are more likely to survive and pass on those traits. Over many generations, these helpful traits become more common.

The English naturalist charles-darwin is well known for explaining how evolution works. In 1859, he published On the Origin of species, where he described how natural selection could lead to the gradual change of species. Darwin’s ideas were later supported by discoveries in genetics, which showed how traits are passed from parents to offspring through DNA.

Evidence for evolution comes from many scientific fields. Fossils show how life has changed over time, displaying forms that link ancient species to modern ones. Comparative anatomy shows that many animals share similar body structures, like the bones in human arms, bat wings, and whale fins. Embryology studies early development in animals and finds patterns that suggest common origins. Modern genetics also supports evolution by showing similarities in DNA among different species.

Evolution is still happening today. bacteria can develop resistance to antibiotics, and plants and animals continue to adapt to changing environments. Evolution does not happen quickly—it takes thousands or even millions of years. It is one of the main ideas in biology, helping scientists understand life’s history, diversity, and how living things continue to change.