Palynology
Palynology is the science of fossil and modern pollen, spores, algal cysts, and other microscopic plant bodies. It is a multi-disciplinary field with applications in forensic science, geology, geography, botany, entomology, zoology, archaeology, immunology, and environmental sciences. The term palynology is derived from the Greek terms paluno, meaning to strew, or to sprinkle, and suggestive of palé, meaning fine meal, or the Latin pollen, meaning also fine flour or dust.
The study of palynology has, by necessity, been closely associated with the development and later improvements of microscopes. Because pollen grains are microscopic, mankind had to wait until the invention of the compound microscope in the mid 1600s before pollen grains could be seen in any detail. During the next two centuries following the invention of the microscope, botanists studied the morphological features of pollen grains, their form and structure, and began to develop taxonomic keys for their identification.
Pollen carries the male gametes of flowering and cone-bearing plants, and spores are the asexual reproductive bodies of ferns, mosses, and fungi. Plants produce vast quantities of microscopic pollen and spores, which they disperse with the help of animals, wind, or water. Although individual pollen grains are invisible to the naked eye, they occur on almost every surface in nature. They are also highly resistant to decay, being found in rocks many millions of years old, and also persisting on or in soil, dirt, and other materials for many years. Pollen and spores come in an infinite variety of shapes and have complex surface ornamentation. Each plant type has distinctive pollen that can be distinguished from the pollen of other plants. For this reason pollen and spores are often called nature's fingerprints for plants.
The major commercial application of palynology is in geology, where it is used to date sediments to assist in petroleum, mining, and underground water exploration. Aeroallergy is the branch of medicine concerned with the seasonal occurrence, abundance, and allerogenic effect of spores and pollen. The study of extant palynomorphs, which are either living, still retain their cell contents, or whose cell contents have been removed by maceration, is called actuopalynology. It includes the disciplines mellisopalynology (study of pollen in honey or other bee products), pollination ecology (distribution of pollen by wind or animals and its efficacy in fertilization and seed set), aeroallergy, and criminology (i.e., forensic palynology). In the discipline of archaeological palynology pollen, spores, and other palynomorphs from archeological sites are employed to reconstruct prehistoric diet, funeral practices, artifact function and source, archaeological feature use, cultivation and domestication of plants, and human impact on vegetation.
The term forensic palynology refers to the use of pollen and spore evidence in legal cases. It is often possible to be very specific about where a person or thing has been from the pollen types that occur together in a sample. Pollen and spore production and dispersion are important considerations. The expected production and dispersal patterns of spores and pollen (called pollen rain) for the plants in a given region will yield the type of "pollen fingerprint" to expect in samples that come from that area. Therefore, the first task of the forensic palynologist is to try to find a match between the pollen in a known geographical region with the pollen in a forensic sample. Knowledge of pollen dispersal and productivity often plays a major role in solving such problems.
Pollen can help destroy or prove alibis, link a suspect to the scene of a crime, or link something left at the crime scene to a suspect. It can also help to determine what country or state drugs, food, merchandise, and antiques among other things, have come from. In its broader application, the field of forensic palynology also includes legal information derived from the analysis of a broad range of microscopic organisms such as dinoflagellates, acritarchs, and chitinozoans that can be found in both fresh and marine environments. One of the earliest successful cases where forensic palynology was used pertained to a criminal case in Austria in 1959.
Soil, dirt, and dust are common elements at almost every crime scene. Woven cloth, woolen blankets, ropes, clothing, and fur all make excellent traps for pollen and spores. Woven materials and fur are made of tiny interwoven fibers. When air comes in contact with woven materials, the fibers become filters that retain solid particles, such as pollen and spores. Woolen garments, including blankets, skirts, suits, ties, and sweaters, make the best pollen and spore traps.
If working on a case, pollen is extracted from exhibits (washed or scraped from items, or taken off with tape lifts); control samples are collected; and if possible, the crime scene attended. The samples are then taken through various preparation procedures so that the detail of the pollen can be examined with microscopes. Some cases are quite easy and require only the comparison of assemblages in the control and forensic sample; others require much research in the laboratory with other scientists, the public, and police.
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