Deep Phylogeny−−How a Tree Can Help Characterize Early Life on Earth
Eric A. Gaucher, James T. Kratzer and Ryan N. Randall
Cold Spring Harb Perspect Biol 2010, doi: 10.1101/cshperspect.a002238
The Darwinian concept of biological evolution assumes that life on Earth shares a common ancestor. The diversification of this common ancestor through speciation events and vertical transmission of genetic material implies that the classification of life can be illustrated in a tree-like manner, commonly referred to as the Tree of Life. This article describes features of the Tree of Life, such as how the tree has been both pruned and become bushier throughout the past century as our knowledge of biology has expanded. We present current views that the classification of life may be best illustrated as a ring or even a coral with tree-like character- istics. This article also discusses how the organization of the Tree of Life offers clues about ancient life on Earth. In particular, we focus on the environmental conditions and tempera- ture history of Precambrian life and show how chemical, biological, and geological data can converge to better understand this history.