To learn more about forensics and the natural world, come see Jennifer Menken on the U's state fair stage at noon, Thursday, Aug. 25, and 11 a.m. Monday, Aug. 29, in a 20-minute program geared to children.
For more state fair happenings, see the U's state fair Web site.
Of blowflies and blown alibis
How biology can put a criminal behind bars
By Deane Morrison
Published on August 24, 2005
Most of us don't think much about blowflies--the very name is enough to evoke a grimace of disgust. But blowfly larvae, as well as beetles, pollen, seeds, and other bits of biological material, sometimes bear silent witness to the time or place of a crime. Jennifer Menken, a naturalist at the University's Bell Museum, will share her knowledge of how biology can put a criminal behind bars as she presents "Plants and Animals in Forensics" on the U of M stage at the state fair. She will present a 20-minute program, geared to children, at noon Thursday, Aug. 25, and 11 a.m. Monday, Aug. 29. In the plant world, the best material for placing a suspect at the scene of a crime is pollen. Plants shed pollen only at certain times and locations, and its presence can make things very uncomfortable for miscreants. "There was a case in Germany where a man killed another man, and investigators found boots in the suspect's house," says Menken. "The man denied he'd been at the scene where the dead man was killed or went missing." But the boots told a different story. On them were two types of regular pollen and one type of fossilized prehistoric pollen, which happened to be found only in one place in Germany: near the crime scene. That put an end to the murderer's alibi.
Blowflies like to lay eggs in corpses, often in open wounds, the mouth, or the eyes. The age of the maggots may indicate how long the body has been dead.Some types of pollen prove more useful than others. For example, the pollen of dandelions occurs in so many places it would hardly link anyone to a specific locale. But if a dead body found in a desert should contain pollen from cattails, which grow in marshy areas, then the body may have been moved. Blowflies like to lay eggs in corpses, often in open wounds, the mouth, or the eyes. They have a regular course of development, and the age of the maggots may indicate how long the body has been dead, especially if coupled with information about temperatures and other weather conditions the body was exposed to. But a lot of maggots look the same, so often the maggots taken from a body must be raised to adulthood in a laboratory so entomologists can make a definite identification. "Flies usually land on a body in the first few days," says Menken. "Then other flies are attracted by the different rotting smells." Different flies like different conditions. For example, some may prefer to lay eggs where it's warm and sunny, so a body found in a cold, dark place with eggs from such a fly may well have been moved. As the body gets drier, beetles appear. (Some of these beetles have other uses, too. One type of beetle that appears on drier bodies is used at the Bell Museum to clean animal bones for display.) On the U of M stage, Menken will unroll a blanket full of evidence pertaining to a fictional crime and invite the audience to match their wits against the perpetrator's. Not to worry; she won't be displaying any rotting corpses, and tiny evidence like pollen will be simulated by easily visible balls. So take a gander and learn how modern Sherlock Holmeses crack some tough cases. If you know a child who's interested in this subject, the Bell Museum runs a summer camp, Forensic Science, for one week most years. Visit the museum's Web site for updates.
Other state fair stories: