The term ‘palynology’ is based on the Greek word for ‘the study of powder and dust.’ Thus, palynology is the study of the microscopic structures of plants and animals that are resistant to decay. This includes various organic organisms such as spermatophyte pollen, spores, and dinoflagellates.
Forensic palynology is the application of the study of pollen and spores to investigate legal matters in criminal and civil cases, often used to establish links between objects, people, and places based on the analysis and identification of pollen.
Pollen and Spores:
Pollen and spores are the tiny, powder-like reproductive units of plants. Pollen is utilized in sexual reproduction. In contrast, spores are for asexual reproduction. They can be obtained from an extensive range of items, thus providing clues about the source of the materials and the environment’s characteristics from which they are sourced. Pollen can be classified by size, shape, color, and features of their apertures and ornamentation.
Pollens are produced in great numbers by plants, and been tiny and light-weighted, are dispersed throughout the immediate environment in several ways. Either via wind, insect, or another method. For example, anemophilous plants produce pollen to be distributed by wind. While Zoogamous plants use rodents and bees to disperse their pollen, Autogamous plants self-pollinate and produce their own pollen.
Forensic Significance:
Forensic palynologists often use large-scale collections of pollen to aid in the identification of certain plant species. The advantage lies in a combination of their abundance, dispersal mechanisms, resistance to mechanical and chemical destruction, microscopic size, and morphology. Their abundance, tiny size (typically less than 50 um), and numerous dispersal mechanisms ensure that they are transported away from scenes of interest inadvertently without providing any visual clue to a suspect. On the other hand, their complex morphology allows the identification of an individual parent plant taxon related to a specific ecological habitat or a specific scene, their relative frequency, and areas of the year where they occur.
Spores and pollen are used frequently in criminal investigations like theft, rape, terrorism, bombing, arson, tracing of drugs, poaching, hit and run cases, etc. Following are some examples of how forensic palynology can be helpful in a criminal investigation.
- To establishes the relation between the suspect and the crime scene.
- To establish the link between an item and the crime scene.
- Traces history of traveling (thus positively indicates where a person or object has been).
- Traces environmental information of the primary crime scene.
- To proves the presence of the victim and perpetrator at the crime scene.
- It helps in shortlisting the suspect window.
- Specifies whether the crime scene is primary or secondary.
- Assists in the determination of Human remains deposition duration.
Numerous high-profile cases involving forensic palynology and recent advancements in multi-disciplinary approaches in the environmental analysis have earned public and law enforcement attention in the field due to the possibility of gaining more accurate and detailed information regarding the crime scene in criminal investigations.
Reference:
Mildenhall DC, Wiltshire PE, Bryant VM. Forensic palynology: why do it and how it works. Forensic Sci Int. 2006 Nov 22;163(3):163-72. doi: 10.1016/j.forsciint.2006.07.012. Epub 2006 Aug 21. PMID: 16920303.
Photo credit: Dartmouth Electron Microscope Facility, Dartmouth College
