The Tree of Life Explorer calculates cousin and removal relationships and the age of common ancestors using 12 detailed trees of life (formally known as phylogenies). Each branch segment on each of these trees has a beginning and an end noted in millions of years before the present (abbreviated Ma), and a generation time for that branch segment, noted in years per generation. From these data, the Explorer calculates the number of generations on each branch segment. The Explorer then notes the age (Ma) when any two branches join (which defines the age of a common ancestor), and totals up the generations in the segments that make up a single branch. By comparing the total number of generations to a common ancestor along any two branches on the Tree of Life diagram, the Explorer is able to calculate the cousin and removal relationship. By adding up the generations across multiple trees, or even all 12, the Explorer can calculate the cousin relationship, and time of common ancestry, between any two living things, or anything that has ever lived, on the Evogeneao Tree of Life.