Tree of life (biology)

The tree of life is a metaphor which expresses the idea that all life is related by common descent.

Charles Darwin was the first to use this metaphor in modern biology. It had been used many times before for other purposes.

The evolutionary tree shows the relationships among various biological groups. It includes data from DNA, RNA and protein analysis.

Tree of life work is a product of traditional comparative anatomy, and modern molecular evolution and molecular clock research. Below is a simplified version of present-day understanding.