Relatives on Jupiter

While touring Harlech Castle in Wales, U.S. Physiologist Sanford Siegel found a wallside spot that had been often used as an open-air urinal. Not everyone would react the same way, but it made Siegel think of his job--studying what organisms survive in hostile environments. After scooping up some well-urinated and therefore ammonia-rich earth, he conscientiously lugged it back to his lab at the Union Carbide Research Institute in Tarrytown, N.Y. What he stumbled on, writes Siegel in Science, was a microorganism that may be the living descendant of a recently discovered microfossil that is 2 billion years old. He may also have found a clue to possible life on Jupiter.

Siegel and his associates incubated the soil in a hostile ammoniac atmosphere, and fed it with a nutrient broth. Within weeks, there appeared a strange microorganism, umbrella-shaped, with radiating spokes and a stalk terminating in a bulb. Though unfamiliar with anything like it, Siegel noted that the organism flourished amid conditions resembling the ammonia-laden atmosphere that probably prevailed on earth when the earliest forms of life were developing, some 3 billion years ago.

How Do You Do. Three months after Siegel's discovery, Harvard Paleontologist Elso S. Barghoorn reported that he had found 2-billion-year-old microfossils near Kakabeka Falls in western Ontario. Among them were a number of fossils that bore no resemblance to any living organism. One was an elaborate structure that Barghoorn named Kakabekia umbellata. When Siegel saw a photograph of Kakabekia, he exclaimed: "I've seen that thing before." Indeed, some specimens of Barghoorn's fossil and Siegel's living organism were remarkably similar. "When photographs of the two were compared," says Karen Roberts, one of Siegel's research assistants, "it was difficult to distinguish which was which."

Siegel's discovery poses a fascinating possibility that has long intrigued other scientists. The earth's once ammonia-and methane-rich atmosphere has since been recast through the release of subterranean gases and the evolution of oxygen-producing photosynthetic plants. Siegel believes that the Kakabekia-like organism has survived for "a billion years or more" by living on ammonia from the breakdown of proteins in earth. Citing spectroscopic analyses of Jupiter, which indicate that its atmosphere still contains large amounts of ammonia, Siegel theorizes that space explorers on Jupiter may some day meet living relatives of his discovery.

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