The Tree of Life. With Darwin from Genesis to Genomics

Almagest, 2012

Today, the picture of an evolutionary tree or "Tree of Life" is an icon of evolution. Biologists consider it the most direct representation of evolution (its branches symbolize the evolutionary history of species). Also, the teaching of the ancestry and relationships of living beings to many is almost impossible without it. But this was not always so. How people became convinced that a "tree" was the right way to depict evolution? What are the consequences for the general public of depicting evolutionary relationships as "real" trees, with a main trunk of progress? This article takes a historical approach to show how the tree image became a central part of early evolutionary theory and helped biologists understand Charles Darwin's radical proposals. It also shows that even though the picture of a "real tree" to convey the process of evolution is not strictly Darwinian, pictures of evolutionary trees spread very widely as explanatory devices into museums and textbooks. Finally it shows modern representations of evolutionary trees, as today's biologists are devising new ways to represent the process.

Systematic Biology, 2013

Poroi, 2020

Tree-like visualizations have played a central role in taxonomic and evolutionary biology for centuries, and the idea of a “tree of life” has been a pervasive notion not only in biology but also in religion, philosophy, and literature for much longer. The tree of life is a central figure in Darwin’s Origin of Species in both verbal and visual forms. As one of the most powerful and pervasive images in biological thought, what conceptual and communicative work has it enabled? How have the visual qualities and elements of the tree form interacted with biological thinking over time? This paper examines the pre-Darwinian history of tree images, the significance of Darwin’s use of such images, and the development of tree diagrams after Darwin. This history shows evidence of four separate traditions of visualization: cosmological, logical-philosophical, genealogical, and materialist. Visual traditions serve as rhetorical contexts that provide enthymematic backing, or what Perelman calls “objects of agreement,” for interpretation of tree diagrams. They produce polysemic warrants for arguments in different fields. The combination of the genealogical tradition with the cosmological and the logical changed the framework for thinking about the natural world and made Darwin’s theory of evolution possible; the later materialist tradition represents the “modernization” of biology as a science.

Arbor, 2013

This article uses a review of a number of tree diagrams to highlight how the fact that Darwin was to choose the metaphor of a tree to describe evolutionary relationships between organisms should come as no great surprise, as the tree already occupied an important position in European iconography. In the review of some of the uses of a "tree" to represent different types of relationships in the pre-Darwinian age, we want to illustrate two basic issues. One particularly important issue is that Darwin had the insight of including various symbols and metaphors that were already being used to represent different aspects of the living world in his own theory of evolution, particularly the general metaphor of branching and rebranching. The other is that when Darwin published On the Origin of Species in 1859, people were already familiar with the idea of a tree to represent genealogy. This may have been an important factor in people's familiarity with evolutionary diagrams and also in strongly associating them with religious metaphors.

Archives of Natural History, 2012

To speak of evolutionary trees and of the Tree of Life has become routine in evolution studies, despite recurrent objections. Because it is not immediately obvious why a tree is suited to represent evolutionary history – woodland trees do not have their buds in the present and their trunks in the past, for a start – the reason why trees make sense to us is historically and culturally, not scientifically, predicated. To account for the Tree of Life, simultaneously genealogical and cosmological, we must explore the particular context in which Darwin declared the natural order to be analogous to a pedigree, and in which he communicated this vision by recourse to a tree. The name he gave his tree reveals part of the story, as before Darwin's appropriation of it, the Tree of Life grew in Paradise at the heart of God's creation.

Biology continues to use the Tree of Life image to show the temporal continuity and discontinuity of the living beings. Moreover, the development of genetic, molecular biology and paleontology has originated phylogenetics. This discipline studies evolutionary relatedness among various groups of organisms through molecular sequencing data and morphological data matrices. The Tree off ers interesting points for semiotic perspectives and for theological approaches too. The symbolic reading of the Tree of Life, on the one hand, and the analogies with the Biblical genealogies and some Christian images, on the other hand, will be explored.

This article is a fully referenced research review to overview progress in unraveling the details of the evolutionary Tree of Life, from life's first occurrence in the hypothetical RNA-era, to humanity's own emergence and diversification, through migration and intermarriage, using research diagrams and brief discussion of the current state of the art. The Tree of Life, in biological terms, has come to be identified with the evolutionary tree of biological diversity. It is this tree which represents the climax fruitfulness of the biosphere and the genetic foundation of our existence, embracing not just higher Eucaryotes, plants, animals and fungi, but Protista, Eubacteria and Archaea, the realm, including the extreme heat and salt-loving organisms, which appears to lie almost at the root of life itself. To a certain extent the notion of a tree based on generational evolution has become complicated by a variety of compounding factors. Gene transfer is not just vertical carried down the generations. There is also evidence for promiscuous incidences of horizontal gene transfer, genetic symbiosis, hybridization and even the formation of chimeras. This review will cover all these aspects, from the first life on Earth to Homo sapiens.

2014

Archives of Natural History, 2011

As part of the Darwin celebrations in 2009, the Natural History Museum in London unveiled TREE, the first contemporary artwork to win a permanent place in the Museum. While the artist claimed that the inspiration for TREE came from Darwin's famous notebook sketch of branching evolution, sometimes referred to as his “tree of life” drawing, this article emphasises the apparent incongruity between Darwin's sketch and the artist's design – best explained by other, complementary sources of inspiration. In the context of the Museum's active participation in struggles over science and religion, the effect of the new artwork is contradictory. TREE celebrates Darwinian evolutionism, but it resonates with deep-rooted, mythological traditions of tree symbolism to do so. This complicates the status of the Museum space as one of disinterested, secular science, but it also contributes, with or without the intentions of the Museum's management, to consolidate two sometimes conflicting strains within the Museum's history. TREE celebrates human effort, secular science and reason – but it also evokes long-standing mythological traditions to inspire reverence and remind us of our humble place in this world.