Plant Detectorists: Part 1 – Can Plants Be Used To Detect Human Remains?

“Pushing up daisies: Margravine Cemetery” by Stefan Czapski is licensed under CC BY-SA 2.0

Pushing Up Daisies?

As a former professional plant physiologist (and semi-lapsed plant-related blog-scribbler), I still occasionally peruse the plant literature to see what’s new.

In doing so, I sometimes come across an article with a title that certainly piques my curiosity. Such an enticing article, recently published online in Trends in Plant Science, is entitled “Plants to Remotely Detect Human Decomposition?” (see Ref. 1 below).

How could I resist?

Taking only about 15 minutes to read, this relatively brief paper turns out to be mostly a speculative article.

The paper begins with the following pitch: “In the USA, 100 000 people go missing every year. Difficulty in the rapid identification of sites of human decomposition complicates the recovery of bodies, especially in forests. We propose that spectral responses in tree and shrub canopies could act as guides to find cadavers using remote sensing platforms for societal benefit.” (From Ref. 1 below)

The authors, from various departments at The University of Tennessee Knoxville, suggest that it may be possible to “pinpoint” human remains in forested areas by detecting specific foliar changes in trees. Such changes may be detectable by “unmanned aerial vehicle (UAV)-based remote sensing”.

To quote the authors: “A large nitrogen input or subtle changes from stress responses, chlorosis, and compromised cellular architecture could possibly be identified in plant canopies by UAV-based remote sensing technologies. UAV technologies are increasingly becoming less expensive and more versatile by efficiently flying function-specific sensors (e.g., biochemical, thermal-IR, and hyperspectral sensors). With this technology, forensic investigators can make decisions about which signals to investigate from specific case information. (from Ref. 1 below)

Since the authors conclude with a list of “Important Research Questions to Enable Plant-Based Sensing of Human Cadavers“, this article, to me at least, reads like a brief research proposal.

If this seems like a very strange proposal for plant scientists, it’s important to note that at least one of the authors is connected to the Forensic Anthropology Center (FAC) at The University of Tennessee Knoxville. And the FAC is responsible for The Body Farm, where various aspects of the decomposition of cadavers are studied.

Plants already have somewhat of a connection to cadavers via the realm of forensic botany, that is, using plants to solve crimes, including murder cases. But I admit that my botanical knowledge is lacking when it comes to the scientific literature pertaining to the use of plants to detect dead bodies.

Cursory online Google Scholar searches of the subject – what search terms would you use? – revealed quite an extensive literature regarding how decomposing bodies affect the soil mineral composition and microbiology, as well as the vegetation (see, for example, Refs. 2 and 3 below).

Plant Detectorists

These investigations about using plants to detect cadavers got me thinking about other ways plants are used to detect things in the soil. Which led me to remember stories about how old-time gold prospectors may have used above-ground plants to detect below-ground gold deposits. Which, in turn, led me to remember the brilliant BBC TV series “The Detectorists”. (Hence the inspiration for the title of this blog post.)

Anyway, notions of using plants as environmental biosensors (plants as “detectorists”, if you will) to detect both inorganic substances (e.g., heavy metals, such as gold) and organic molecules (e.g., pollutants, explosives, etc.) have been around for decades. But the advent of the internet, CRISPR, and nanotechnology has recently reinvigorated this subject, leading to new fields of plant research (e.g. “cyborg botany“).

Because of this, I’m thinking it might be fun and interesting to explore the subject I’ll call “plant detectorists” to see how plants have been used as environmental biosensors and also to investigate what’s new and exciting.

TO BE CONTINUED….

References

1. Brabazon, H. et al. (2020) “Plants to Remotely Detect Human Decomposition?” Trends in Plant Science, DOI:https://doi.org/10.1016/j.tplants.2020.07.013. (Full Text)

2. Caccianiga, M., S. Bottacin and C. Cattaneo (2012) “Vegetation Dynamics as a Tool for Detecting Clandestine Graves.” Journal of Forensic Sciences, Vol. 57, pp. 983-988. (Abstract)

3. Steyaert, S.M.J.G., et al. (2018) “Special delivery: scavengers direct seed dispersal towards ungulate carcasses.” Biology Letters, Vol. 14: 20180388. http://dx.doi.org/10.1098/rsbl.2018.0388 (Full Text)

Elvis Costello – “Watching the Detectives”

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