Chemical 'crumbs' from microbes' snacks provide a trail to ancient, r...( en the missing cookies and the crumbs w...)

Anbar's team found an "imposter," a chemical process that doesn't necessarily involve any living organisms but nevertheless leaves evidence that scientists had thought might only be due to microbes. The team turned its attention to iron, a particularly appealing indicator for scientists because it's present in a majority of rocks, creating many potential candidates for signs of ancient life. Researchers studied the properties of different chemical forms of iron and found that simple chemical processes in the laboratory can account for the proportions that scientists previously believed indicated past life. The scientists suspect the same chemical signatures could be created naturally in groundwater and sediments whether life is present or not.

Much of the laboratory work was done by chemistry graduate student Jo Roe. She fed different forms of iron into a small vertical column, then measured the rate at which different isotopes of iron traveled through this chemical environment. Formerly a nurse, Roe decided to switch careers and obtained bachelor's and master's degrees in chemistry before joining Anbar's laboratory and joining the hunt for exotic life. Also contributing to the project were research scientist Jane Barling of the Department of Earth and Environmental Sciences, and scientist Kenneth Nealson of the Jet Propulsion Laboratory in California.

The work comes as scientists are rapidly expanding their criteria for environments that can support life. Living organisms have been found at the bottom of the ocean, far from any light source, and in highly acidic environments. With each of these findings, the possibility that life exists or once existed in a harsh or remote outpost of our solar system, like Mars or one of Jupiter's moons, moves up a notch. Says Anbar: "Life can exist in a much wider variety of conditions than we thought before. People are optimistic that t
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Contact: Tom Rickey
trickey@admin.rochester.edu
716-275-7954
University of Rochester
6-Apr-2000