The
primordial organic soup that spawned
life on Earth may have gotten some
special ingredients from outer space, according to scientists at the
Carnegie Institution. Their study, appearing in Meteoritics and Planetary Science,
reports concentrations of
amino acids in two
meteorites that are more
than ten times higher than levels previously measured in other similar
meteorites. This finding suggests that the early
solar system was far
richer in the organic building blocks of life than scientists had
previously thought.
Amino acids form the backbone of proteins, which in turn build many of
the structures and drive many of the
chemical reactions inside living
cells. The production of proteins is believed to constitute one of the
first steps in the emergence of life. While scientists believe that
amino acids could have
formed in some environments on the early Earth,
the presence of these compounds in meteorites also points to space as a
potential contributor.
The meteorites in question are a type called CR chondrites. They date
from the time of the solar system''s formation and were collected in
Antarctica in 1992 and 1995. The researchers speculate that the
meteorites were part of a larger "parent body," such as an asteroid,
which was shattered by impacts.
"The amino acids probably formed within the parent body before it broke
up," says researcher Conel Alexander. "For instance, ammonia and other
chemical precursors from the solar nebula, or even the interstellar
medium, could have combined in the presence of water to make the amino
acids. Then, after the break up, some of the fragments could have
showered down onto the Earth and the other terrestrial planets. These
same precursors are likely to have been present in other primitive
bodies, such as comets, that were also raining material onto the early
Earth."
More abstracts about the Meteorites Spiced Up Primordial Soup