Early natural classification 's fold-out paleontological chart in his 1840
Elementary Geology Although tree-like diagrams have long been used to organise knowledge, and although branching diagrams known as
claves ("keys") were omnipresent in eighteenth-century
natural history, it appears that the earliest tree diagram of natural order was the 1801 "Arbre botanique" (Botanical Tree) of the French schoolteacher and Catholic priest
Augustin Augier. Yet, although Augier discussed his tree in distinctly genealogical terms, and although his design clearly mimicked the visual conventions of a contemporary
family tree, his tree did not include any evolutionary or temporal aspect. Consistent with Augier's priestly vocation, the Botanical Tree showed rather the perfect order of nature as instituted by God at the moment of Creation. In 1809, Augier's more famous compatriot
Jean-Baptiste Lamarck (1744–1829), who was acquainted with Augier's "Botanical Tree", included a branching diagram of animal species in his
Philosophie zoologique. Unlike Augier, however, Lamarck did not discuss his diagram in terms of a genealogy or a tree, but instead named it a
tableau ("depiction"). In 1840, the American geologist
Edward Hitchcock (1793–1864) published the first tree-like
paleontology chart in his
Elementary Geology, with two separate trees for the plants and the animals. These are crowned (graphically) with the
Palms and Man. The first edition of
Robert Chambers'
Vestiges of the Natural History of Creation, published anonymously in 1844 in England, contained a tree-like diagram in the chapter "Hypothesis of the development of the vegetable and animal kingdoms". It shows a model of
embryological development where fish (F), reptiles (R), and birds (B) represent branches from a path leading to mammals (M). In the text this branching tree idea is tentatively applied to the history of life on earth: "there may be branching". In 1858, a year before Darwin's
Origin, the paleontologist
Heinrich Georg Bronn (1800–1862) published a hypothetical tree labelled with letters. Although not a creationist, Bronn did not propose a mechanism of change. File:Augier tree of life.jpg|
Augustin Augier's 1801
Arbre botanique ("Botanical Tree")
David Penny has written that Darwin did not use the tree of life to describe the relationship between groups of organisms, but to suggest that, as with branches in a living tree, lineages of species competed with and supplanted one another. Petter Hellström has argued that Darwin consciously named his tree after the biblical
Tree of Life, as described in
Genesis, thus relating his theory to the religious tradition. File:Darwin Tree 1837.png|Page from Darwin's notebooks () with his first sketch of an evolutionary tree, and the words "I think" at the top File:Origin of Species.svg|Diagram in Darwin's
On the Origin of Species, 1859.It was the book's only illustration. The letters A–L represent distinct descents. Each horizontal line represents 1000 generations. Descent A has 3 existent species after 10000 generations. Descent I has 2. Descents E, F have 1 each. The other descents have gone extinct.
Haeckel Ernst Haeckel (1834–1919) constructed several trees of life. His first sketch, in the 1860s, shows "
Pithecanthropus alalus" as the ancestor of
Homo sapiens. His 1866 tree of life from
Generelle Morphologie der Organismen shows three kingdoms: Plantae, Protista and Animalia. This has been described as "the earliest 'tree of life' model of
biodiversity". His 1879 "Pedigree of Man" was published in his 1879 book
The Evolution of Man. It traces all life forms to the
Monera, and places Man (labelled "") at the top of the tree. File:Ernst Haeckel - Tree of Life.jpg|
Haeckel's
Stammbaum der Primaten (1860s) File:Haeckel arbol bn.png|Haeckel's tree of life in
Generelle Morphologie der Organismen (1866) File:Tree of life by Haeckel.jpg|The tree of life as seen by Haeckel in
The Evolution of Man (1879)
Developments since 1990 was released, with 2,274 studies and 50,632 species, represented in a spiral tree of life, free to download. In 2015, the first draft of the
Open Tree of Life was published, in which information from nearly 500 previously published trees was combined into a single online database, free to browse and download. Another database,
TimeTree, helps biologists to evaluate phylogeny and divergence times. In 2016, a new tree of life (unrooted), summarising the
evolution of all known
life forms, was published, illustrating the latest
genetic findings that the branches were mainly composed of bacteria. The new study incorporated over a thousand newly discovered bacteria and archaea. In 2022, the fifth version of
TimeTree was released, incorporating 4,185 published studies and 148,876 species, representing the largest timetree of life from actual data (non-imputed). ==Horizontal gene transfer and rooting the tree of life==