| Meteorites Not Sugar-free, NASA Finds | |
Adding more evidence to support the theory that life on Earth came from outer space, NASA scientists have discovered another building block of life -- sugar -- in meteorites.
Mainly carbon-based units, we humans also have our also sweet side. "Sugar chemistry appears to be involved in life as far back as our records go," said Dr. George Cooper of NASA's Ames Research Center, Moffett Field, California.
Years ago, researchers found meteorites containing carbon and carbon-based compounds that play major roles in life on Earth, such as amino acids and carboxylic acids, but none that contained sugars.
That all changed when Dr. Cooper and his associates reported finding a sugar called "dihydroxyacetone" and several sugar-like substances, known as sugar acids and sugar alcohols, in the Murchison and Murray meteorites.
According to the "life from outer space" theory, meteorites and comets that bombarded the Earth in great numbers from 3.8 billion to 4.5 billion year ago carried with them life-essential organic compounds, such as oxygen, sulfur, hydrogen and nitrogen. These compounds then combined in the hot waters of ancient Earth in just the right quantities and under just the right conditions to spawn life.
Sugars and related compounds called "polyols," are also known to be critical to life as basic components of RNA and DNA. Until Dr. Cooper's team found these substances in the Murchison and Murray meteorites, scientists were at a loss to explain how they found their way into primordial Earth's "soup of life."
"Finding these compounds greatly adds to our understanding of what organic materials could have been present on Earth before life began," stated Dr. Cooper. "Recent research using ratios of carbon isotopes have pushed the origin of life on Earth to as far back as 3.8 billion years."
Finding the building blocks of life on Earth in meteorites and comets, NASA scientists project that these "starry messengers" may have spread life throughout the universe.
"This discovery shows that it's highly likely organic synthesis critical to life has gone on throughout the universe," said Kenneth A. Souza, acting director of astrobiology and space research at Ames. "Then, on Earth, since the other critical elements were in place, life could blossom."
Dr. Cooper's research is reported in a paper, "Carbonaceous Meteorites as a Source of Sugar-related Organic Compounds for the Early Earth," published in the Dec. 20 issue of Nature Magazine.
Both
the Murchison and Murray meteorites are famed examples of "carbonaceous"
meteorites containing numerous amino acids and a variety of other organic
compounds that are thought to have played a role in the origin of life.
