Washington, D.C.—The building blocks of life may have emerged in volcanic eruptions on the early Earth, according to a new analysis of classic experiments performed more than fifty years ago. Using modern techniques to examine samples from the original experiments, researchers discovered previously undetectable organic compounds. The results, reported in the October 17 issue of Science, point to the possible contribution of volcanism to the beginning of life on Earth.
The original experiments, performed by Stanley Miller at the University of Chicago in 1953 and 1954 (Miller died in 2007), were the first to demonstrate that the basic molecules of life could be synthesized by subjecting hydrogen-rich gases (such as methane and ammonia) to an electric spark, simulating lightning in the primordial atmosphere. Scientists no longer think that the primordial atmosphere as a whole had the make-up assumed by Miller's experiments, but the clouds of gases emitted during volcanic eruptions do have a hydrogen-rich composition. Volcanic eruptions may have been very common during the planet's hot, early stages.
"It turns out that some of the experiments Miller performed simulated the steam from volcanic eruptions, in addition to the more famous experiments that simulated a hydrogen-rich atmosphere," says H. James Cleaves, of the Carnegie Institution's Geophysical Laboratory, one of the paper's co-authors and Miller's last graduate student. "And when we analyzed samples left over from these volcanic experiments, they contained the most varied mixture of compounds."
Cleaves points out that lighting is very commonly associated with volcanic clouds, and could have been an abundant source of energy to convert simple compounds into organic molecules.
The samples from Miller's original experiments were preserved by Cleaves and Jeffrey Bada, Miller's first graduate student and now a professor at the University of California, San Diego. He and Adam Johnson, an Indiana University graduate student and lead author of the Science paper, discovered the vials among Miller's effects after his death in 2007.
In addition to Johnson, Bada, and Cleaves, the research team included Jason Dworkin and Daniel Glavin (NASA Goddard Space Flight Center) and Antonio Lazcano (Universidad Nacional Autonoma de Mexico).
Funding for the study was provided by the NASA Astrobiology Institute, the Marine Biological Laboratory in Woods Hole, Mass., Mexico's El Consejo Nacional de Ciencia y Tecnologia, and the Carnegie Institution for Science.
The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
The NASA Astrobiology Institute (NAI), founded in 1998, is a partnership between NASA, 16 U.S. teams, and five international consortia. NAI's goal is to promote, conduct, and lead interdisciplinary astrobiology research and to train a new generation of astrobiology researchers. For more information, see http://astrobiology.nasa.gov/nai.