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Microbes That Keep Time

After someone dies, their microbiome changes in ways that researchers say could be used to gauge how long it's been since death occurred, even after a couple of months, Scientific American reports. This could be a useful tool for forensics, the researchers say, as entomology-based approaches to determining time of death can be influenced by temperature, weather, and geography, among other factors.

Researchers from the John Jay College of Criminal Justice at the City University of New York sampled the ears and noses of 17 cadavers and collected repeat samples from four of those cadavers over the course of weeks of decomposition at a body farm. As they reported in PLOS One this week, they sequenced those microbial samples and used them to build an algorithm to determine time since death. For unknown samples, the researchers found that their model could estimate the post-mortem interval with an average error of 55 degree-days, which is about two days in the summertime.

"And that held out for up to six to seven weeks. And that's way better than entomology can tell you," senior author Nathan Lents from John Jay College tells Scientific American.

Scientific American notes that approach is not quite courtroom-ready, though Lents says that their machine-learning approach will get better as more data is folded in.