The Rise of Life on Earth
Photographs by O. Louis Mazzatenta
Text by Richard Monastersky
"The Yellowstone microbes are the closest relative to the original ancestor of life we have found so far," says microbial biologist Anna-Louisa Reysenbach. "And the interesting thing is that all the branches close to this original ancestor live in places with high temperatures."
That fact leads some scientists to suspect that life got its start in a scalding environment about four billion years ago, perhaps around the volcanic hot springs on the ocean bottom that spew out superheated fluids laden with metals and with energy-rich compounds that can power some of the chemical reactions thought critical for evolving life. According to this idea, seafloor springs simmered the sterile primordial ocean, causing chemicals to join together in myriad ways to create totally new molecules. Over thousands or perhaps millions of years, those chemical kitchens cooked up the greatest dish ever prepared: life itself.
Although the characters in the Precambrian—the first and longest chapter of Earth’s story—were minuscule (billions could fit in a drop of water), they paved the way for all later organisms. They developed DNA and proteins, the basic molecules that sustain all living cells. They devised ways of harnessing sunlight to produce food. They gave rise to the oxygen we need to survive. They even invented sex.
NGM 1998/03