Evolution

Biological evolution is the change in a population's inherited traits from generation to generation. These traits are encoded as genes that are copied and passed on to offspring during reproduction. Mutations and other random changes in these genes can produce new or altered traits, resulting in inheritable differences (genetic variation) between organisms. Evolution occurs when these differences become more common or rare in a population. This happens randomly through genetic drift, and based on the reproductive value of traits through natural selection.

Natural selection occurs because organisms with traits that help them survive and reproduce tend to have more offspring. In doing so, they will pass more copies of their inheritable traits on to the next generation. This tends to cause advantageous traits to become more common in each generation, while disadvantageous ones become rarer.Over time, this process can result in varied adaptations to environmental conditions.As differences in and between populations accumulate, species may split into new species. The similarities between organisms suggest that all known species are descended from a single ancestral species through this process of gradual divergence.

The theory of evolution by natural selection was first put forth in detail in Charles Darwin's 1859 book On the Origin of Species. In the 1930s, Darwinian natural selection was combined with Mendelian inheritance to form the modern evolutionary synthesis.With its enormous explanatory and predictive power, this theory has become the central organizing principle of modern biology, providing a unifying explanation for the diversity of life on Earth.