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/
