Evolution is the change in inherited characteristics of biological population over successive generations. Evolutional processes gice origin to diversity at all biological organizational levels, includng species, individual organisms and molecules.
All life on earth shares a common ancestor, known as the last universal ancestor, that lived about 3.5-3.8 billion years ago. The repeated forming of new species (speciation), changes within a species (anagenesis), and loss of a species (extinction) over evolutional history of life on Earth are demonstrated by groups of common morphological and biochemical characteristic, including shared DNA sequences. These shared characteristics are more similar between species that share a more recent common ancestor, and can be used to reconstruct a biological tree of life based on evolutional relationships (phylogenetics), using both of the species and existing fossils.
