The "Tree of Life" is a biological term reflecting the shape of evolution through the passage of time. It begins with the trunk, the universal ancestor of life on earth; splits into its major branches, animals, plants, fungi and so on; splits again into smaller branches, mammals, birds, reptiles, and amphibians within the vertabrates; all the way out to the very tips of the branches which represent each individual species.

The Tree of Life represents evolution unfolding through time; the most ancient life begining at the trunk, and the most recent in the twigs.