Tree of Life
This is a tree of life--a diagram that shows how different types of living things, or species, are related. If you follow the lines connecting any two species on the tree, you'll get an idea of how closely related they are. The longer the path is, the more distant the relationship. The 479 species listed on this tree represent only a tiny fraction of the more than 1.7 million species scientists have identified. Many millions more species are believed to exist. Our species, Homo sapiens, is labeled in green in the top left part of the tree.
How was it made?
Generations of scientists have created tree-of-life diagrams by studying and comparing the physical features of different species. But this tree of life was made by comparing DNA sequences, with physical features playing a supporting role. All living things have some DNA sequences in common because they evolved from a single ancestral species. Closely related species have more DNA in common than distantly related species do, so they are positioned closer to each other on the tree.