Discovery Provides Key Evidence Of Life's Beginnings

Two years ago, Timothy Kusky, Ph.D., the Paul C. Reinert Professor of Natural Sciences at SLU, and Jianghai Li, a professor of geological science at Peking University, dug up hundreds of fossilized black smoker chimneys in northern China.

Since then, the researchers have been analyzing the samples in several laboratories. The discovery is important, the researchers say, because it lends support to the theory that life on the planet developed on the sea floor.

Findings the discovery are being reported in the latest issue of Gondwana Research, an international interdisciplinary journal published by Elsevier, the world's leading publisher of science and health information. It is featured as the journal's cover article.

Black smoker chimneys are deep-sea hydrothermal vents. Marine geologists and biologists routinely explore the depths of the ocean in submersibles looking for these chimneys. Scientists have discovered many new species of organisms near active chimneys, including a creature so unusual that it was classified in a phylum of its own.

Because they are home to the most primitive life forms on Earth, fossilized chimneys offer important clues to origins of life on the planet, Kusky said. However, bringing fossilized chimneys found on the ocean's floor to the surface is difficult — they are fragile and easily crumble.

The SLU/Peking chimneys are 1.43 billion years old, the oldest such discovery on record, with previous findings dating back about 500 million years. They're also the largest, with the largest fragment measuring about 3 feet in length, while previous discoveries have been just a few inches long.

Kusky said the age and size of the chimneys will help scientists understand the interaction between ancient hydrothermal processes and the development of life on the sea floor in ways that were not possible before.

"This discovery offers scientists valuable on-land samples for geological and geobiological research with implications for the origin and evolution of early life on Earth," said Kusky, also director of Saint Louis University's Center for Environmental Sciences.

M. Santosh, editor-in-chief of Gondwana Research and professor of geology at Kochi University in Japan, said the paper represents a major advance in the geological sciences and offers important insights for biologists, oceanographers and other scientists.

During their months of testing and analysis, the team discovered a type of ancient microbe that relied on metal sulfide for nourishment lining the fringes of the chimneys.

It's the first known case where such microbes have been shown to have lived within the ancient fossil chimneys.

"This discovery provides tantalizing suggestions that early life may have developed and remained sheltered in deep-sea hydrothermal vents until surface conditions became favorable for organisms to inhabit the land," Kusky said.