Palynology is the study of pollen. It's used to examine plant relationships, date fossils, analyze layers of rock and learn about evolution. Recently, an unexpected new use for palynology has been discovered: crime scene investigation.
Though you don't usually see it, pollen is everywhere — forests, grasslands, deserts, farms, cities, caves, shorelines and more. Because different species of plants live in all sorts of different places and flower at different times, pollen grains carry a particular "signature," as three researchers call it in this story from The Conversation.
This signature makes pollen a biomarker that can link a person to a specific place and time, though establishing that connection requires specialized experts more accustomed to working on dinosaur fossils than homicide cases.
From The Conversation:
Researchers have recently developed a new technique for identifying pollen, using genetics. Since it makes identification much easier and faster for large numbers of pollen samples, we believe this development has the potential to transform forensic palynology, allowing us to harness the power of pollen to solve crimes.
Pollen already has been used as evidence to solve cases around the world. When mass graves were uncovered in Bosnia, pollen on the bodies was used to find the original place of death for each victim. In New Zealand, pollen found on a robbery suspect's clothing linked him to the crime. That pollen came from a rare plant outside the victim's home.
The authors of The Conversation piece say pollen can be extremely useful in cases when evidence has been moved, as in the Bosnia example. It can be examined on objects in a missing person case, or analyzed to ascertain a criminal's travel history.
But there are limitations. With somewhere around 400,000 species of plants on the planet, it can be tricky to identify a specific pollen. Palynology also is a highly specialized field. Only one person is employed as a full-time forensic palynologist in the entire U.S.
Still, a March 2016 study published in Forensic Science International Genetics says pollen can be identified through DNA barcoding and sequencing, a complicated but much more accurate way to narrow down a specific pollen. While there are still some challenges to resolve before forensic palynology becomes commonplace, it's interesting to see how this tiny particle known for irritating our allergies can be used for something good.