Decoding death: Study reveals how microbes could help determine time since death

For the research, scientists inspected 36 human corpses. The bodies were sourced from donors who had consented to their use for scientific purposes before they passed away. The bodies were assigned to so-called 'body farms' at three disparate places - Tennessee, Texas, and Colorado. These areas were selected due to their different climatic conditions - temperate, humid, and semi-arid.

As reported by Live Science, researchers collected DNA samples from the skin of the deceased and the encompassing soil during the first 21 days following death - a phase of rapid and dynamic tissue decay. This data offered a wealth of information, enabling experts to paint a broad picture of the "microbial community," or microbiome, present at every location where the bodies were kept.

Intriguingly, the scientists noticed a pattern across all geographical locations, climates, and seasons, discovering the same set of approximately 20 specialized microbes decomposing on all 36 bodies. As detailed by Phys.com, these microorganisms followed a predictable pattern over the 21-day observation period, with their appearances significantly influenced by insects.

Using data gathered from this study and previous analyses, the researchers then utilized machine learning to develop a unique tool. This tool can determine the time elapsed since death with an accuracy of up to three days. Although the scientists posit that their findings could be beneficial to forensic investigations in various climates and locations, more research is needed to enhance this tool.

The ultimate aim is to enable this tool to be effective under real-life conditions, and not just under those fabricated for the study. Often, bodies are buried, wrapped in different materials, or submerged in water, making them less pleasing to insects, which are critical in these studies. Under these altered circumstances, a body may decompose differently, underscoring the need to assess whether similar microbial patterns still occur.

Prof. David Carter of Chaminade University in Honolulu, a participant in the study, said, "When we talk about examining death scenes, it's important to understand that, unlike other physical evidence like fingerprints, blood stains or CCTV footage which may or may not be present, you can always count on the presence of microbes."