What is evolution?
Evolution is the process by which living things change over many generations. Through natural selection, traits that help organisms survive and reproduce become more common over time.
Individuals in a population vary, and some of these differences are inherited. In any environment, some individuals are better suited to survive and have offspring. Over time, their helpful traits spread through the population. Over very long periods, these changes can lead to new species.
Charles Darwin and Alfred Russel Wallace proposed the theory of evolution by natural selection in 1858, and Darwin published On the Origin of Species in 1859. Since then, evidence from fossils, genetics, anatomy and direct observation has strongly supported the theory. DNA studies show how all living things are related.
Evolution in action
Evolution can be observed today. Bacteria evolve resistance to antibiotics, insects become resistant to pesticides and finches on the Galápagos Islands have changed beak size in response to droughts. Evolution explains the incredible diversity of life on Earth, from bacteria to blue whales.
Did You Know?
Humans did not evolve from modern chimpanzees. Instead, humans and chimpanzees share a common ancestor that lived about 6 to 7 million years ago.