The key to solving countless missing persons mysteries could be found in the treetops above.
When people die in the wilderness or in questionable circumstances their bodies are often never recovered because finding human remains can be incredibly difficult.
But scientists believe the very plants that usually hinder search efforts could one day point detectives in the direction of hidden human remains.
Researchers based at the “body farm” – the Anthropology Research Facility – at the University of Tennessee are looking into whether “cadaver decomposition islands” – the area surrounding human remains – change the nutrient concentrations of the soil and how those changes manifest in nearby plants.
Once this is known, academics will develop ways to scan plants for signals that suggest humans remains are concealed close by.
While the influence of human decomposition on plants needs further exploration, the researchers say it is possible to make body recovery using vegetation a reality.
“In smaller, open landscapes foot patrols could be effective to find someone missing, but in more forested or treacherous parts of the world like the Amazon, that’s not going to be possible at all,” senior author and professor of plant sciences at the University of Tennessee, Neal Stewart, said.
“This led us to look into plants as indicators of human decomposition which could lead to faster and possibly safer body recovery.”
Mr Stewart said it was likely decomposing remains would trigger the release of nitrogen into the soil, especially in the summertime, which could cause changes in leaf colour and reflectance.
But the research has its limitations.
Scientists said other large animals, like deer in the US or kangaroos in Australia, also die in places people may go missing, meaning researchers must find metabolites specific to the breakdown of humans.
“One thought is if we had a specific person who went missing who was, let’s say, a heavy smoker, they could have a chemical profile that could trigger some sort of unique plant response, making them easier to locate,” Mr Stewart said.
“Though at this stage this idea is still far-fetched.”
Once this is determined the research team could scan plants for specific fluorescence or reflectance signals that indicate human remains are close by.
“We’ve actually built a whole plant images that can analyse fluorescence signatures,” Mr Stewart said.
“But the first steps are going to be very fine scale, looking at individual leaves and measuring how their reflectance or fluorescence changes over time when plants are near human remains.”
The next step would be to ramp up the use of drones to scale large bushland or forest areas from above.
“If we can quickly fly where someone may have gone missing and collect data over tens or even hundreds of square kilometres, then we’d know the best spots to send in a search team,” Mr Stewart explained.
He predicts it will take many years before detectives can feasibly use plants as a search tool in body recovery missions.