Although gangsters and pirates may claim that dead men tell no tales, criminal investigators are extremely adept at extracting information from the tiny organisms that live on corpses, revealing all sorts of valuable information about the time and cause of death. However, a new study into the microbes that break down deceased bodies may have now revealed a more accurate method of ascertaining these details, with bacteria and fungi acting like a "death clock," enabling precise predictions about how long a person has been dead.
Publishing their findings in the journal Science, a team of researchers led by Jessica Metcalf from the University of Colorado, Boulder, discovered that the composition of microbial communities around a corpse shifts over time “in a clock-like manner.” Consequently, they conclude that by examining the concentrations of certain types of organisms it may be possible to discern the time of death with unprecedented precision.
Until now, forensic investigators have primarily focused on the state of fly larvae in order to estimate how long a body has been decomposing, although the information this technique provides tends to be slightly vague.
The team behind the latest study did not set out specifically to devise a superior method of determining time of death, but to gather information about the nature of the microbes involved in the decomposition of organic material. More specifically, they sought to determine whether these microbes vary depending on the corpse’s environment, and whether they originate primarily from within the corpse or its surroundings.
They therefore placed both mouse and human corpses in a number of different environments, consisting of varying soil types and temperatures. What they found was that the same microorganisms appeared in each experiment, and that the temporal changes in these communities also followed an identical sequence in all cases.
For instance, nitrogen-recycling microbes were found to be most prevalent during the early stages of decomposition, as the intestinal fluids of the corpse provided a rich source of ammonia. These were later replaced by fungi and nematode worms, all of which originated in the soil rather than within the dead body itself.
Assessing the value of their findings, the team explained that knowledge about changing modes of microbial decomposition over time can provide vital information about the role of dead organic matter in large-scale cycles affecting entire ecosystems.
Additionally, Metcalf claimed in a statement that the experiments enabled researchers to predict the time of death with “jaw-dropping” precision, leading the authors to conclude that “postmortem micro-organisms can provide both spatial and temporal insight into the events surrounding death.”
