1. * Department of Biological Sciences, Columbia University, New York, NY 10027.
2. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138; Department of Computer Science, University of Auckland, Auckland, New Zealand.
3. Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.