Microbes show up on schedule after death

E. coli

MICROBIAL CLOCK  Telltale crews of microbes (including bacteria from a group called Enterobacteria, shown here) colonize the soil beneath a decomposing body during different stages of decay.

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Dead people tell no tales — but dead people’s microbes do.

Bacteria, fungi and worms living in the soil beneath a decomposing body can help reveal the time — and place — of death, scientists report December 10 in Science.

Researchers have tracked the comings and goings of cadaver microbes before, but the new study is the most comprehensive survey yet. For months, microbial ecologist Jessica Metcalf of the University of Colorado Boulder and colleagues tallied up microbes on and near dead mice and humans.

As bodies decayed, similar microbes cropped up like clockwork, even on different soil types and during different seasons of the year, the team found. The microbes were so predictable that researchers could estimate the time of death (within a few days) of a body that had been dead for about a month.

And because telltale microbes stayed in the soil long after a body had been moved, they could offer investigators clues about potential crime scenes, the team suggests.  

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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