Evolution is a change of hereditary characteristics in a biological population expressed through generations. Evolutionary processes support biodiversity at every level of biological organization, including species, individual organisms and genes. It is widely considered that all life on Earth shares a single ancestor known as the „last universal common ancestor“ (LUCA) who lived about 3,5 billion years ago. Through evolution of life on Earth, formation of new species and loss of the old ones constantly takes place. This phenomenon is reflected by changing the external appearance and biochemical characteristics of species, including the sequence of the DNA molecule. Therefore, the tree of life always lives; old branches fall off, but the new ones always emerge.