Trees and networks before and after Darwin

Abstract

It is well-known that Charles Darwin sketched abstract trees of relationship in his 1837 notebook, and depicted a tree in the Origin of Species (1859). Here I attempt to place Darwin's trees in historical context. By the mid-Eighteenth century the Great Chain of Being was increasingly seen to be an inadequate description of order in nature, and by about 1780 it had been largely abandoned without a satisfactory alternative having been agreed upon. In 1750 Donati described aquatic and terrestrial organisms as forming a network, and a few years later Buffon depicted a network of genealogical relationships among breeds of dogs. In 1764 Bonnet asked whether the Chain might actually branch at certain points, and in 1766 Pallas proposed that the gradations among organisms resemble a tree with a compound trunk, perhaps not unlike the tree of animal life later depicted by Eichwald. Other trees were presented by Augier in 1801 and by Lamarck in 1809 and 1815, the latter two assuming a transmutation of species over time. Elaborate networks of affinities among plants and among animals were depicted in the late Eighteenth and very early Nineteenth centuries. In the two decades immediately prior to 1837, so-called affinities and/or analogies among organisms were represented by diverse geometric figures. Series of plant and animal fossils in successive geological strata were represented as trees in a popular textbook from 1840, while in 1858 Bronn presented a system of animals, as evidenced by the fossil record, in a form of a tree. Darwin's 1859 tree and its subsequent elaborations by Haeckel came to be accepted in many but not all areas of biological sciences, while network diagrams were used in others. Beginning in the early 1960s trees were inferred from protein and nucleic acid sequences, but networks were re-introduced in the mid-1990s to represent lateral genetic transfer, increasingly regarded as a fundamental mode of evolution at least for bacteria and archaea. In historical context, then, the Network of Life preceded the Tree of Life and might again supersede it.

Figure 1

Linear order in nature, from the Physicorum elementorum of Charles de Bouelles (1512). Organised bodies (i.e. minerals, vegetables, animals and man) are not explicitly placed within this chain.

Figure 2

Three scales of intellect connecting earth with the abode of God, from the Liber de ascensu et decensu intellectus of Ramon Llull (written 1304, first published 1512). Organised bodies (unusually including fire) are included in the main scale, depicted as a stairway.

Figure 3

Bifurcating key of hyacinth species, from the Methodi herbariae libri tres of Adam Zaluziansky à Zaluzian (1592).

Figure 4

Tree of animal life, from the Zoologia specialis of [Carl] Edward [von] Eichwald (1829). Historian Semyon Mikulinskii (1972) describes this as the first depiction of the tree proposed by Peter Simon Pallas in Elenchus Zoophytorum (1766).

Figure 5

Tree depicting the origin of animals, from the Philosophie zoologique of Jean-Baptiste Lamarck (1809).

Figure 6

More-detailed tree depicting two branching series of animal origins, from the Histoire naturelle des animaux sans vertèbres of Jean-Baptiste Lamarck (1815).

Figure 7

Network of affinities among the natural orders of plants, from the Ordines naturales plantarum commentatio botanica of Johann Rühling (1774).

Figure 8

Network of affinities among animals, from the Tabula affinitatum animalium of Johann (Jean) Hermann (1783).

Figure 9

Network of affinities within the vegetable kingdom, from the Tabula affinitatum regni vegetabilis of August Johann Georg Carl Batsch (1802).

Figure 10

Network of genealogical relationships among breeds of dogs, from William Smellie's translation of the Histoire Naturelle of Georges-Louis Leclerc, Comte de Buffon and Louis-Jean-Marie Daubenton (1753).

Figure 11

System of animals, from Ueber die Entwicklungsstufen des Thieres by Georg August Goldfuss (1817).

Figure 12

System of animal "transits", from De regni animalis limitibus atque evolutionis gradibus by [Carl] Edward [von] Eichwald (1821).

Figure 13

Attempt at an account of the genera of Rutaceae shown arranged according to their mutual affinities, from Adrien de Jussieu (1825).

Figure 14

Universal system of nature, from the Primae lineae systematis naturae of Paulus Horaninow [Pavel Feodorovich Ghoryaninov] (1834).

Figure 15

Quinarian system of birds, from Volume 2 of William John Swainson's On the natural history and classification of birds (1837).

Figure 16

Quinarian system of animals, from Volume I, Part 2 of the Horae entomologicae of William Sharp Macleay (1821). Handwritten annotations (not readily visible at this brightness setting) on this original, from the Fisher Library at the University of Sydney, may have been made by WS Macleay himself.

Figure 17

Quinarian system of animals, from the Horae entomologicae of William Sharpe Macleay (1821). Macleay has superimposed his system on the 1809 evolutionary tree of animals of Jean-Baptiste Lamarck (cf Figure 5).

Figure 18

Hybrid quinarian system of "exogens" (dicotyledenous plants) by John Lindley, from Volume 10 of the Penny Cyclopædia (1838). For detailed discussion see Coggin [81].

Figure 19

Tree diagram of affinities of the bird group Fissirostres, by Alfred Russel Wallace (1856).

Figure 20

System of animals, shown in the form of a tree, as evidenced by the fossil record; by Heinrich Georg Bronn (1858).

Figure 21

The "I think" tree from Notebook B by Charles Robert Darwin (1837). Figure from Wikimedia Commons.

Figure 22

Great Tree of Life, from Origin of Species by Charles Robert Darwin (1859).

Figure 23

Genealogical tree depicting three kingdoms of life, from Volume II of Generelle Morphologie by Ernst Heinrich Haeckel (1866).

Figure 24

"A diagram showing the evolutionary levels of the various algal groups and the mutational activity within each group" from The Algae and their Life Relations. Fundamentals of Phycology by Josephine E. Tilden (University of Minnesota Press, 1937)." The most recently evolved members of the group (Chroococcaceae, Bangiales, Ectocarpales, etc.), shown nearest the center line, are the simplest in form and structure and represent most closely the ancestral type in each case. The oldest or earliest evolved members of the group (Stigonemataceae, Ceramiales, Fucales, etc.), shown farthest from the center, are the most specialized, having undergone, through mutational variations, a more or less complete change from the ancestral type." (Tilden 1937:5). The figure shown is Plate II, page 40; used by permission of the University of Minnesota Press.

Figure 25

Evolution of Conjugales, from Valentine J. Chapman and David J. Chapman, The Algae (1973:334). This figure is representative of evolutionary tree-diagrams in the phycological literature from the late 1800s through the late 1900s in depicting parallel morphoclines of (usually) increasing complexity along which extant species can give rise to others. Macmillan and Co. Ltd, reproduced with permission of Palgrave Macmillan.

Figure 26

Network of lines of relationships among groups of algae and protozoa, by Georg Klebs (1893).

Figure 27

Phylogenetic tree based on small-subunit ribosomal RNA sequences showing three domains of life. Figure from Wikimedia Commons after Carl Woese and colleagues [186].

Figure 28

"A reticulated tree, or net, which might more appropriately represent life's history", by W. Ford Doolittle. Figure reproduced from [171] by permission of the American Association for the Advancement of Science.

Figure 29

Network showing major ("highways") of gene relationships in prokaryotes, by Robert Beiko. Figure reproduced from [165].

Figure 30

Network representation of vertical inheritance and lateral exchange among prokaryotes, by Tal Dagan and William Martin. Reproduced from Figure 2(e) of [167] by permission of the Royal Society.