David J. Gibson (Oxford University Press)
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THEY called him the Sherlock Holmes of France 鈥� and, in fact, his antics did inspire the novelist Arthur Conan Doyle.
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When Edmond Locard established his forensic science lab in 1912, the world had never seen anything like it. The place wasn鈥檛 much to look at 鈥� cramped quarters on the fourth floor of the Palais de Justice in Lyon 鈥� but there Locard set about laying the foundations of a completely new scientific discipline.
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As befits the time, his methods involved self-experimentation, including a study to find out whether fingerprints can be burned off. They can鈥檛. He also spent years examining 鈥渄ust鈥� 鈥� microscopic detritus ranging from bacteria to sloughed-off bits of human. But it was his scrutiny of plant fragments that really put him ahead of his time.
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Fast-forward a century and forensic botany is still in its infancy, as David J. Gibson makes clear in Planting Clues. In addition to Locard, we meet other pioneers of this rapidly developing science, including Jane Bock, a plant anatomist who was phoned out of the blue one day in 1982 by a coroner who wanted to know whether it was possible to deduce the last meal of a dead woman from the contents of her stomach.
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Bock and her colleague David Norris set about chewing food samples 32 times 鈥� just like your grandmother told you to 鈥� spitting them out and then examining the gloop under a microscope. All that chewing paid off and their evidence helped to solve the case.
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Another groundbreaker was Tim Helentjaris. In 1993, while working as a plant geneticist at the University of Arizona, he showed that DNA extracted from seed pods discovered in a suspect鈥檚 truck matched a blue palo verde tree at the site where a body had been found. The case was the first time that genetic evidence from a plant had been admitted in court.
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Planting Clues contains many tales like these, where forensic botany is a key witness in cases of murder or rape. They can make for uncomfortable reading. Besides, if you are a regular watcher of crime dramas like CSI or Silent Witness, you are probably already aware of the ways in which plant materials can link suspects with victims and/or the scene of a crime.
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But there is so much more here. Gibson recounts the case of Delgamuukw v British Columbia, in which microscopic pollen was used to support a land claim based on oral history made by the Gitxsan and Wet鈥檚uwet鈥檈n people in British Columbia, Canada.
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He goes on to describe a marijuana database that contains DNA from 3000 varieties of cannabis and hemp, provides 3D interactive maps showing their evolutionary relationships and can even offer the flavour profile and pedigree of a particular plant.
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Gibson also tells us that humans eat just 3000 of the 400,000 known plant species, with the typical Western diet containing only 70 or so 鈥� which is a very helpful fact if you are trying to work out which vegetables someone ate before they died.
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His writing is fascinatingly horrible when it comes to describing rotting human corpses, with details that might escape even the most thorough and up-to-date TV series. First, the body releases caustic, plant-killing fluids, then it adds around 2.6 kilograms of nitrogen fertiliser to the soil. Gibson calls the result a 鈥渃adaver decomposition island鈥�, consisting of a plant-free area surrounded by lush vegetation.
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Chapter 6, entitled 鈥淎 forensic pharmacopoeia鈥�, is even more intriguing. Do you know how many fly agaric mushrooms it takes to kill a healthy adult? And did you know that famous fungal homicides may include the death of Siddhartha Gautama, who was known as the Buddha? Or that atropine, a toxin produced by deadly nightshade, can be used as an antidote in some cases of mushroom poisoning?
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Of course, fungi aren鈥檛 plants. But by including them in this wide-ranging survey of forensic botany, Gibson shows just how much the natural world is involved in our human interactions, for good or ill.
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