Sept. 9, 2004

Gretchen Cook-Anderson 
Headquarters, Washington 
(Phone: 202/358-0836) 

NOTE TO EDITORS: N04-142

MOLECULAR BIOLOGISTS UPROOT PERSPECTIVE OF ANCIENT ANCESTRY

A study funded in part by NASA has uprooted the "Tree of Life" 
metaphor that describes how all organisms are related. 

The new perspective, reported in today's issue of the journal Nature, 
has produced significant implications for eukaryotes (cells with 
nuclei). The group includes all multi-cellular forms of life, 
including humans, animals and plants. 

"It's not a tree; it's actually a ring of life," said Dr. James A. 
Lake, professor of molecular biology, University of California at Los 
Angeles (UCLA). "A ring explains the data far better." 

The "Tree of Life," with its evolutionary branches and roots showing 
groups of bacteria on the bottom and multi-cellular animals on the 
higher branches, therefore is a misnomer according to Lake. 

"Through the use of genomics, we show the fusion of two microbial 
groups created the first eukaryote," Lake said. "There have been 
theories, but we have never known where eukaryotes came from before. 
Eukaryotes inherited two sets of genomes from very different 
microbial groups that do not have a cellular nucleus, called 
prokaryotes," he said.

NASA, the National Science Foundation, Department of Energy, and the 
National Institutes of Health funded the research, based on an 
analysis of more than 30 genomes.

Lake conducted the research with Maria Rivera, a research scientist in 
UCLA's department of molecular, cell, and developmental biology, and 
the university's astrobiology program.

For information about astrobiology at NASA on the Internet, visit: 

http://astrobiology.arc.nasa.gov/ 

	
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