Tree of Life
From Palaeos
The Tree of Life can refer to a mythical or religious concept, a motif in various world theologies and philosophies, a phylogenetic metaphor.
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[edit] Mythology
Many ancient and traditional cultures incorporate the myth of the World Tree, or Tree of Life, Tree of Knowledge, Tree of Speech, and so on.
The Assyrian Tree of Life is represented by a series of nodes and criss-crossing lines. It is often attended to by Eagle Headed Gods/Priests or the King himself.
In Germanic or Nordic mythology the World Tree or Yggdrasil of the Eddas is a giant yew or ash tree that links and shelters all the worlds.
In Hebraic mythology the Tree of Life is mentioned in the Books of Genesis, in which it grants immortality to Adam and Eve. In Christianity it also occurs in the Book of Revelation, in which it is referred to as the Word of Life.
In Mayan mythology the center of the universe is associated with a tree of life, Whac Chan, symbolised by a great ceiba tree that is uniting the nine levels of Xibalba, the underworld, with the surface of the Earth and the thirteen heavens.
In the Tongan/Fijian myth of creation there is at the beginning of things the "Tree of Speech" which, like the giant Ash Yggdrasil, this is the gathering place of the gods, and the tree grows by a fountain, the Water of Life.
[edit] Metaphysics and Theology
In Hinduism the Bhagavad-Gita refers to the Asvattha (Ficus religiosa, popularly known as the Bodhi tree or Enlightenment Tree) or world tree as growing with its roots in the heavens, and its trunk and branches extending downwards to earth. Its leaves are the Vedas (sacred scriptures); its branches the three qualities (gunas), and the lesser branches the sense-objects.
In the system of Kabbala (esoteric Judaism) the "Tree of Life" (see diagram at right) refers to the cosmo-theological representation of Deity in terms of ten Sephirot (archetypal attributes) and twenty-two connecting paths, which formed the basis of elaborate metaphysical speculation.
There are also diagrams that are tree-like, although not specifically represented as trees. For example the Egyptian and Greek theogonies, or geneologies of the Gods, trace the origin of all the gods and hence all creation back to an original God or primal principle (e.g. chaos). More abstract and universal are the Indian Samkhyan diagram of tattwas (evolutes), and Neoplatonist Proclus' tabulation of the emanation of principles from the One to the body. All of these ideas represent proto-evolutionary metaphysical speculations (although they more specifically refer to involution rather than [evolution]]).
[edit] Science
In evolutionary science, the Tree of Life is used as a phylogenetic metaphor. In this evolutionary context, the tree of life describes the relationships of all life on Earth.
Charles Darwin talks about envisioning evolution and ecosystems as a "Tangled Bank" in The Origin of Species, however the book's sole illustration is of a branched diagram that is very tree like.
The theme of the Tree of Life more specifically appears more recently (19th century) in the writings of the Darwinist philosopher and scientist Ernst Haeckel, who was the first (I think) to represent living organisms in a phylogentic tree. His book "General Morphology - founded on the the Descent Theory" traced the origin of all life to Moneren. This was the trunk from which all the branches (represneting the various phyla and classes) emerged. Haeckel was also the first to propose that the ancestry of humans was among the Great Apes, and placed man (Menschen in the drawing) at the very top of the tree, among the Affen ("apes").
Haeckel's "tree of life" diagram (and variations thereon) was repeated in many books.
In the later twentieth century the Haeckelian tree was superceded by by more precise cladistic-inspired cladograms and dendrograms, found both in books and on the web.
The Tree of Life on the Web is an ongoing Internet project containing information about phylogeny and biodiversity, produced by biologists from around the world. Each page contains information about one group of organisms and is organized according to a branched tree-like form, thus showing hypothetical relationships between organisms and groups of organisms.
The UCMP website also presents a phylogenetic arrangement of groups of organisms, although not as technical as the Tree of Life Web Project.
These projects have also been supplemented by a number of amateur ascii phylogenies, pioneered by Mikko's Phylogeny Archive (the largest supertree on the web) and the old Dinosauricon, and also the basic phylogenetic approach here at Palaeos.
The goal of all these cladistic and phylogenetic trees is ultimately and ideally to map the entire evolution of life on Earth down to the smallest branches, although in practice such attempts will never be complete because of the limitations of the fossil record.
[edit] Credits
MAK061011. This page incorporates material from: Kheper - MAK990907
