Life from Radioactivity

Art Z over at href="http://cheerfulcurmudgeon.com/2006/10/22/bacteria-use-radioactive-uranium-instead-of-energy-from-the-sun/">Cheerful
Curmudgeon links to an interesting story about subterranean href="http://newsinfo.iu.edu/news/page/normal/4229.html">bacteria
that derive energy from radioactive uranium.  

"What really gets my juices flowing is the possibility of
life
below
the surface of Mars," said Tullis Onstott, a Princeton University
geoscientist and leader of the research team. "These bacteria have been
cut off from the surface of the Earth for many millions of years, but
have thrived in conditions most organisms would consider to be
inhospitable to life. Could these bacterial communities sustain
themselves no matter what happened on the surface? If so, it raises the
possibility that organisms could survive even on planets whose surfaces
have long since become lifeless."

Pratt, Onstott and former graduate student
Li-Hung Lin (the paper's lead author, now at National Taiwan
University) and colleagues present evidence the bacterial communities
are indeed permanent -- apparently millions of years old -- and depend
not on sunlight but on radiation from uranium ores for their
existence. 

I think we will learn a lot by studying how these critters came about.
 The evidence so far suggests that they diverged from other
bacteria about 3 to 25 million years ago.  That is fairly
recent, and a bit of a surprise to me.  We'll see what
subsequent research shows.