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By Rossella Lorenzi, Discovery News
Did a Meteorite Seed Earth?
Italian
researchers claim to have found conclusive evidence that
life on Earth arrived from outer space.
Bruno
D'Argenio, a geologist working for the Italian National
Research Council, and Giuseppe Geraci, professor of molecular
biology at Naples University, identified and brought back
to life extraterrestrial microorganisms lodged inside 4.5
billion-year-old meteorites kept at Naples' mineralogical
museum.
"When
in contact with a physiological solution, they became visible
and began to move," D'Argenio said while presenting
the finding at the Italian Space Agency yesterday.
The
bacteria, called "cryms" (for crystal microbes)
by the researchers, remained dormant for billions of years
and survived extreme ambient conditions — a clear indication,
according to the researchers, that "life can exist
everywhere in the solar system, though in a quiescent state."
Once
brought back to life, the cryms were cloned by the researchers
and their DNA analyzed.
"Their
genetic code is unlike any known on Earth," said Giovanni
F. Bignami, scientific director of the Italian Space Agency.
In studying
the bacteria, the team found that they tend to gather in
clusters. The bugs are also killed easily with antibiotics.
Disputing
critics who suggested that the meteorites were contaminated
with terrestrial microorganisms, Bignami added that the
bacteria came back to life after the samples were sterilized
at 950 degrees Celsius and doused in alcohol.
The
discovery, if borne out, would strengthened the "panspermia"
theory, first suggested by chemist Svante Aarhenius in 1900.
According to this theory, outer space seeded Earth with
primitive life forms about 4 billion years ago. The theory
was recently supported by Noble Prize winner Francis Crick,
as well as noted scientists Fred Hoyle and Chandra Wickramasinghe.
"Life
would have formed as an initial seed in the protoplanetary
nebula from which all the planets originated. This microorganism
can be found ... in planetary bodies and in the meteors
fallen to Earth," said Bignami.
The
Italian researchers have also identified microorganisms
identical to the "cryms" found in the Naples meteorites
in 50 samples of billion-year-old terrestrial rocks from
five continents.
"I'm
skeptical, very skeptical," biologist Martino Rizzotti
of Padua University told the daily newspaper La Stampa.
"Those bacteria seem to be too similar to the terrestrial
ones. I can't avoid thinking about possible contaminations."
Margherita
Hack, director of the Inter-University Regional Center for
Astrophysics and Cosmology in Trieste, is more positive.
"It is very likely that life is spread in universe.
This is an interesting result, but it requires more study
to be completely accepted," she said.
Today
the researchers present their findings at the Accademia
dei Lincei (Academy of the Lynxes) in Rome, a prestigious
scholarly organization that counts Galileo Galilei among
its members.
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