The Tree of Life is an ever-evolving depiction of life’s common ancestry. Scientists design the Tree of Life from careful observations and comparisons of living things. The tree shows that all organisms are related through their descent (the branches) from a common ancestor (the root).
The more structural and genetic similarities that organisms share, the more closely related they are and the closer they are on the Tree of Life.
Darwin’s Tree of Life
“The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species.” -On the Origin of Species
Darwin sketched a tree of life to illustrate his idea of descent with modification. It is the only illustration in On the Origin of Species.
Your Extended Family
Trace your own evolutionary relationships on this modern Tree of Life (below). The four colored lines show how humans are related to dogs, leeches, mushrooms, and the bacterium E.coli.
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