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2008 Annual Science Report

Pennsylvania State University Reporting  |  JUL 2007 – JUN 2008

Genomic Record of the Earth's Early Biosphere (Hedges)

Project Summary

Our research involves molecular evolutionary genetics in an effort to better understand the relationship between planetary history and the evolution of life. We continue to update our public database TimeTree (, which presents divergence times of organisms. Most of the work during the past year involved editing and contributing to a book, The Timetree of Life, which summarizes the current state of knowledge in the field and presents new data, with 81 chapters and 105 authors (Oxford University Press, in production).

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Our database TimeTree ( was released in 2006 it presents divergence times of organisms from the published literature (timetrees are phylogenies scaled to time). The initial development of the database was supported by a grant from NSF. Astrobiologists and others are interested in knowing if there is a consensus in the field regarding a specific divergence time, the range of times proposed, the robustness of a given time estimate, and the researchers working on specific divergence times for particular groups of species. However, there are ~3,000 publications presenting divergence times and the data (timetrees) are multidimensional and hierarchical, requiring a sophisticated tree-traversing knowledgebase. During the past year we identified and coded 400 new studies for addition to TimeTree.

The PI (Hedges) and collaborator Sudhir Kumar (ASU) were both on sabbatical last year and spent most of that time working on and contributing to a book, The Timetree of Life (Hedges and Kumar, Eds.), which is now in production at Oxford University Press. It has 81 chapters and 105 authors (480 p.) and will be released in early 2009. It summarizes the current state of knowledge in the field, across all groups of organisms down to the family level. Each chapter is authored by one or more experts on the specific group, and timetrees are presented, and thus it is essentially an encyclopedia of the tree of life—the first of its kind. It will be a reference work for biologists and scientists in other fields, including astrobiologists.

    Jaime Blair

    Sudhir Kumar

    Fabia Battistuzzi
    Unspecified Role

    S. Blair Hedges
    Unspecified Role

    Matthew Heinicke
    Unspecified Role

    Objective 4.1
    Earth's early biosphere

    Objective 4.2
    Foundations of complex life

    Objective 4.3
    Effects of extraterrestrial events upon the biosphere