July 31, 2008
Signs of Life Found Inside Rock Salt
have long searched for traces of ancient life on Earth in order to understand
the history of life on our planet.
bones have helped us understand the age of the dinosaurs.
Insects trapped in drops of amber have inspired Hollywood films and researchers
alike. These remnants of ancient life on Earth provide important clues about
our planet's past.
of researchers working in New Mexico has found traces of life inside salty
halite crystals. The discovery is "an invaluable resource for understanding
the evolutionary record [of Earth] over a geological time frame,"
according to Jack Griffith of the University of North Carolina, Chapel Hill and his colleagues, who recently published their work in the journal Astrobiology.
may even help scientists search for signs of life on
more commonly known as "rock salt" and can be found all over the
planet in the form of salty crystals. These crystals may not seem all that
interesting at first glance. However, inside of them are tiny pockets of water
that can be very valuable for scientists. Halite crystals form in liquid as
evaporation occurs. The crystals naturally trap small amounts of liquid during
this process. These water pockets and all that they contain can be protected
inside halite crystals for extremely long periods of time. The crystals in the
recent study had drops of water that were 250 million years old.
crystals have kept these tiny water drops safe for an astonishing length of
time ... but the story doesn't end there. Scientists discovered abundant amounts
of cellulose fibers inside the water. Cellulose is present in many living
cells. One of the most common places to find cellulose is as a component in the
cell walls of plants. Cellulose is also produced by single-celled organisms
importantly for astrobiologists, cellulose is only formed by living organisms.
If cellulose is present, there must have been life.
the research team, cellulose is a very sturdy material and the fibers were
stable enough to survive until today. Additionally, the samples were collected
from deep below the ground, where they had been protected from radiation.
The cellulose found in the New Mexico halite is now the oldest biological
macromolecules ever isolated. In addition, the researchers were able to
visualize the fibers and study their biochemistry. Because of this, the 250
million-year-old cellulose is now providing a window into the history of life
cellulose can survive for 250 million years inside halite on Earth, it may be
possible for similar molecules to survive in halite crystals on other planets.
is a common component in organisms on Earth. According to the authors of the
study, "over 100 gigatons of cellulose are produced each year" on our
planet. It is used by bacteria to make biofilms. Plants and algae use cellulose
to help build their physical structures. The bodies of insects contain a
molecule very similar to cellulose called chitin.
If life on
other planets is similar to life on Earth, it is possible that alien
organisms might use molecules similar to cellulose. As this new study shows,
these molecules could possibly survive for millions of years, even if their
home planet is no longer habitable today.
If we can
find halite on other planets, the crystals may be an excellent place to search
for proof of ancient life. The researchers are hoping to examine even older
samples of halite on Earth in the future to determine if biomolecules like
cellulose can survive even longer inside the crystals. If future studies are
successful, halite crystals could become an important target for future
exploration missions to Mars and beyond.