Traces

by Patricia Wiltshire

  The King Kong of naturally produced poisons and toxins are the alkaloids. They are produced by bacteria, fungi, and plants, and are even present in some animals, such as poison frogs and toads, although these amphibians get the poison from the ants they eat and, presumably, the ants get it from the plant material they gather. The evolutionary advantage given to a frog from the plants is truly stunning.

  Alkaloids are derived from the building blocks of proteins, and many have familiar names – atropine, nicotine, morphine, mescaline, adrenaline, ephedrine, and quinine. The vast array of alkaloids has thus been exploited for medicines; but the borderline between a poison and a therapeutic agent may, again, simply be concentration or dose. Tomato, potato, aubergine, pepper, and chilli are all valuable foods, but they are all in the same family as deadly nightshade, with its tempting black berries, and Datura (jimson weed), with its beautiful white flowers. In reality, they all contain the alkaloid solanine and, although even some supermarket managers do not realise it, the greening of potato skin heralds the production of the poison. Solanine is a potent pesticide and it protects the plant from being attacked by pathogens but, so often, what is toxic to an insect, a worm, or a fungus will, inevitably, be poisonous to us too.

  Strychnine is a well-known alkaloid toxin from trees and shrubs in the genus Strychnos, native particularly to southern India. A potent neurotoxin, it is well known because it was favoured as the poison used in murder mysteries by authors such as Agatha Christie. It is rather an obvious poison for modern murders, but plants in the buttercup family – Delphinium, Paeony, Aquilegia – also accumulate deadly alkaloids in their tissues and, in 2009 in west London, Lakhvir Kaur Singh, after being abandoned for a younger woman, was convicted of spiking her partner’s curry with monkshood (Aconitum), a beautiful purple flower from the same family. Every part of the monkshood plant is highly poisonous, and one of its effects is that it promotes motor weakness and paralysis, eventually interfering with the function of your heart and lungs. For this reason, like strychnine, it has a long history in murder, and after eating the curry, Singh’s victim vomited, began to lose his vision and the use of his limbs, and died within an hour of arriving at hospital.

  There are about 200 species of Aconitum; they were used, variably, to eliminate criminals and enemies in ancient Rome, and to poison arrowheads in medieval warfare. Singh had laced the victim’s curry with Aconitum and was eventually sentenced to life imprisonment for the premeditated attack. She was the first person to be prosecuted for murder with this type of toxin since the doctor George Henry Lamson killed his 18-year-old brother-in-law, Percy John, by delivering a poisoned slice of Dundee cake to his boarding school in 1882.

  Fungi produce a most bewildering array of compounds, many of which are toxic, and many being helpful to us. Fungi are the source of many antibiotics, which are, of course, effective in killing bacteria. In nature, this prevents bacteria from swarming all over the fungal body, thus preventing it from absorbing food. Without the beneficial effects of fungi, nearly all animals and plants would fail to survive as they are essential for the ways they obtain their food; they are essential for the production of most of our food too. But, beware, the most poisonous have no remedy, and many of these are in the fungal genus Amanita. The destroying angels (Amanita virosa in the UK and Amanita bisporigera in the USA), and the death cap (Amanita phalloides), are particularly dangerous because they resemble edible fungi. However, Caesar’s mushroom (Amanita caesarea) is safe and delicious, and is sought after for its lovely flavour. In Europe and the USA, Amanita is responsible for about 95% of all deaths in mushroom poisoning, with the death cap being responsible for about 50% on its own.

  The problem with fungal poisoning is that the symptoms do not manifest themselves for at least six to 15 hours, and, in some species, up to a week or more, by which time it is too late even to attempt treatment. In any event, nothing can be done and death ensues. Certain fungi, then, seem the perfect agent for murder without detection. It is easy to imagine that, in the past, plants and fungi have been a rich source of poisons for nefarious purposes and details of the death throes of the Emperor Claudius suggest that his fourth wife, Agrippina, was following in the family tradition by poisoning his food, this time with mushrooms, possibly Clitocybe or Inocybe, which have the highest levels of the alkaloid muscarine.

  Many fungi produce alkaloids, the ergot fungus (Claviceps purpurea) being perhaps one of the most famous. It infects the female part of grass and cereal flowers, particularly those of rye, and produces dark bodies called ‘sclerotia’ which replace the whole seed of the plant. The sclerotium behaves like a seed too and gets dispersed with the cereal grain, becoming mixed up with flour and finding its way into bread. The fungus produces a complex of alkaloid compounds; some have the effect of causing strong uterine contractions, and this property was harnessed to cause abortions in the 17th and 18th centuries. Some of the alkaloids also cause mental confusion and vasoconstriction, especially of the hands and feet, creating a burning sensation – the so-called St Anthony’s fire. Where the sclerotia were used by doctors for the purposes of securing abortion, many women died and lost limbs because the dosage was so hit and miss.

  The fungus also synthesises lysergic acid, the precursor of LSD, and unfortunates who consumed the fungus, either accidentally or purposefully, were plagued by hallucinations. It has been suggested that the preposterous accusations made in the Salem Witch Trials in 1692 and 1693 were the result of people eating infected rye bread. Vast numbers of people all over Europe have died from ergotism, including 40,000 in Aquitaine in AD 944. The first known reference to this disease is from Assyrian tablets from about 600 BC and from India in about 350 BC. Wherever people grew wheat rather than rye, they were relatively safe as wheat is more resistant to the fungus.

  Deliberate poisoning might be rare in the modern age, but the potential for intoxication is all around us. Swallowing a tiny amount of the alkaloid coniine, in the hemlock plant (Conium maculatum), will inhibit the working of your body’s neuromuscular junctions, paralysing you first in the legs and then spreading upwards through the body until it reaches your lungs and finally kills you. Socrates must have had a nasty death.

  One of the most potent plant poisons of all comes from the seeds of the castor oil plant, which contains high intensities of the toxin ricin. This is yet another class of toxin, a kind of protein which prevents other organisms from making their own proteins. Just four seeds from the castor oil plant can lead to an excruciating death from vomiting, diarrhoea, and, in only a few days, multiple organ failure. In fact, ricin has such potency that it has been turned into a weapon of war, classified as a controlled substance by the 1972 Biological Weapons Convention, and used by various terror groups in assassination attempts against US politicians. In a famous case, the Bulgarian playwright Georgi Markov, who had defected to the West in 1968, was assassinated in Waterloo, London, by a member of the Bulgarian secret police who used a modified umbrella to fire a tiny pellet laced with ricin into his leg.

  But although plant poison is not the modern murderer’s most obvious weapon of choice, there are other circumstances in which a forensic ecologist might be called upon to look at plant and fungal remains where toxicological analysis fails. Certain toxins produce devastating effects on a body, but others are harnessed for other, mind-altering effects – and even taken recreationally. Plants and fungi have been being esteemed for their psychotropic effects since prehistoric times.

  The red fungus with the white spots (Amanita muscaria) produces ibotenic acid and muscimol, compounds with similar effects to lysergic acid diethylamide (LSD). Even reindeer seek out this prettiest of fungi, presumably because of the pleasurable experiences they get from it, and it has been used ritually by the peoples occupying the Tundra as far back as anyone knows. One of the effects of these hallucinogenic compounds is that when under its influence, you might think you can fly, and many a death has needed investigation after devotees have thrown themse
lves from buildings with outstretched arms. Even Santa Claus, flying with his reindeers in his red and white suit, might be related to stories originally told by followers of the cult of this fungus. Many mushroom cults have existed, and still exist today, some simply associated with pleasurable experiences and others with religious ones. The basis of some religions, and even cultural behaviour, seem to have stemmed from hallucinogenic experiences after consumption of some mushroom or other; and fungal emblems and depictions are common in ancient pictographs.

  In popular television, forensic investigators are infallible and can always identify mysterious compounds central to the story, but it is chastening to realise that, even today, toxicology is often utterly impotent in identifying toxins unless the analyst is given some idea of what is suspected. Sophisticated analytical techniques are available, but just imagine the size of the library of reference samples needed to compare chemical structures of the thousands and thousands of unknown substances. If plant or fungal tissue or spores were involved, direct observation with the microscope can be successful in putting a name to the possible source of a toxin, but here an experienced botanist or mycologist is essential, and we are a dwindling breed.

  Ancient cultures, and the rainforest native tribes persisting today, have possessed, and still have, intimate knowledge of the botanical and mycological heritage surrounding them. Many fungi and plants gathered from the steaming forests, and having psychotropic properties, continue to be part of their normal lives; they play important roles in tribal cohesion and structure. Many of the plants are toxic, but in the right concentrations and combinations that have been learned over eons of time by chosen elders, witch doctors and shamans, ill effects seem to have been minimised. Brews of various combinations of tropical leaves, stems, and even roots can give heightened awareness, and endow feelings of euphoria, well-being, and elicit religious experiences. One can well understand that certain native peoples have vast knowledge on safe dosages and the species mixtures needed for specific kinds of experience to happen. But could you honestly imagine, say, a carpenter from Yorkshire, or a car salesman from Guildford, having sufficient competence to be a shaman? Well, surprising as it may seem, some in Britain and probably elsewhere in Europe supplement their income by ministering concoctions of mind-altering substances to groups of like-minded individuals.

  One afternoon, I received a telephone call from a fairly excited police officer. He had taken into custody a man who had held a shamanistic ceremony and shared an exotic brew with 16 people one summer’s evening in 2008. Most of the group had been having a thoroughly predictable and enjoyable time, but one young man became agitated and then went berserk. None of the 15 others, who also drank the same infusion, suffered any ill effects, only the hallucinatory and euphoric experiences they had been promised.

  The brew the shaman had served up was called ‘ayahuasca’ and it has been used, in various forms, for centuries – perhaps even millennia – by indigenous peoples of South America to induce healing, hallucination, and out-of-body experience. Ayahuasca brews are ordinarily based on the macerations of two rainforest climbing plants which, like so many in the rainforest, look rather similar even though they are not related. Invariably, the brew contains Banisteriopsis caapi and, depending on the effect the shaman is hoping his brew will provoke, various other plants such as Chullachaqui caspi. But, commonly, a partner for this mixture is Psychotria viridis, and this was the one chosen in this case.

  Banisteriopsis caapi contains alkaloids which can inhibit the enzymes in our gut that would break down serotonin (the happy hormone). These inhibitors are called harmala alkaloids – harmine, harmaline, and tetrahydroharmine. Serotonin keeps us in a good mood; it contributes to our feeling of well-being, appetite, memory, and sleep, and, when we get clinical depression, it may be the over-efficient removal of this hormone by our own bodies that creates the problem. Some antidepressants act by preventing the naturally produced serotonin from being removed so that it is able to reach the active centres in the brain.

  In ayahuasca, it is the second plant, Psychotria viridis, that provides the active psychoactive ingredient, dimethyltryptamine (DMT), and this is the compound that provides the out-of-body and other extraordinary experiences. Its compounds are kept safe from our body’s destructive enzymes by the first plant in the brew. The enzyme inhibitor must be present in any mixture or the active principle in other plants would not be able to survive the gut, get into the bloodstream, and pass the blood-brain barrier. Though traditional shamans likely had other, more fantastical explanations, it is the effect of DMT on the brain that is responsible for the other-worldly hallucinations; and the serotonin working so suddenly is largely responsible for the euphoria experienced by the participant.

  The mind-altering substance DMT can be purchased, but it is a Class A psychedelic drug which is stronger than either LSD or the effects of magic mushrooms. This means that it is illegal to have it in one’s possession, to give it away or sell it, and the maximum penalty for possession is seven years’ custodial sentence. These were serious implications for this shaman operating in that leafy, country town in the UK.

  In that fateful summer of 2008, something had gone terribly wrong for the young man. The shaman, who had prepared the ayahuasca for him and his friends, had kept to the same recipe he had followed before. But this devotee’s hallucinations seemed to be of a different order from those of the others; he ranted and raved and, when his friends took him away from the heart of the ceremony to calm him down, he slipped into a comatose state. He remained that way for four days and four nights. Throughout that time, his body still seemed to function – though raggedly, at best. Without being able to control the muscles, he became incontinent and his friends wrapped him in what nappies they could get together, keeping him as clean and comfortable as they could.

  Indigenous societies may have seen vomiting and diarrhoea as a necessary, and welcome, result of the ayahuasca ritual. Shamans would deliver their brews with the specific purpose of purging the mind of demons through hallucinatory experiences, but the concoction also purges the gut and rids it of intestinal worms taking up residence there. Indigenous societies, then, invoke purging and vomiting to keep people healthy but the young man who died in the care of his friends experienced no benefit from his part in the experience. These friends had no option but to call the police when he died.

  The first time I had ever heard of ayahuasca was when I spoke to that police officer. Cases like these do not come up every day, and the novelty of having arrested a shaman had clearly impressed him. He had already sent off samples to be analysed for the presence of dimethyltryptamine (DMT), and the results had come back positive. And yet the cause of death for this young man could not be established. The police knew that there was DMT in his body, but 15 other people had drunk the same ayahuasca brew that evening, with no apparent ill effects. No doubt if the police subjected them to the same testing, DMT would have been found in their bodies too. The question we were confronted with was: why him? Why had this young man perished where others had lived? Was something else involved in his very negative reaction?

  The police had already made some headway in their investigations by the time I was asked to be involved with the case. When the group of depressed ceremony participants admitted that their friend also indulged in magic mushrooms from time to time, the police sorted through the man’s rooms and found various flasks, a biscuit barrel, and a plastic container. A drawer from his bedroom contained a whole, dried mushroom. What was the mushroom he had been keeping? What had been in these containers and flasks? Had it contributed, in some way, to his death?

  I was tasked with providing answers to these questions.

  My husband, David, was able to start piecing this puzzle together as soon as he saw the fungus; he identified it as Psilocybe semilanceata and confirmed this diagnosis by microscopic examination of its spores. This is the commonest magic mushroom and it actually pops up on our back lawn at home from t
ime to time. It is one of the ‘LBJs’ – the little brown jobs that are not easy for most people to identify precisely (although those who want to use them seem able).

  I knew too that there were ways we could find out what had been in these containers. Working as an environmental archaeologist, one of my most spectacular successes had been to prove that a ‘wine strainer’, buried with a Druidic medical practitioner in his grave in Colchester, about 2,000 years ago, had contained a concoction made from mugwort (Artemisia vulgaris), a common wasteland weed. Mugwort is a relation of wormwood and has long been used in herbalism. The wormwoods and mugworts contain vast arrays of alkaloids, monoterpenes, and many other compounds and, in the past, had sundry medicinal uses. People and domestic animals were dosed with mugwort tea to paralyse intestinal worms so that they could easily be passed out of the gut. Worm infestation was a fact of life for ancient people and clues to their misery have been gained from frequent findings of nematode worm eggs in ancient latrine deposits. As intimated from the field data and laboratory analysis, this Iron Age doctor in Colchester had been treating his patients with mugwort infusions for intestinal worm infestation, and possibly bacterial infections. Because of the plant’s bitterness, he had been adding honey to the medicine. This was so convincingly clear because, although there were occasional pollen grains of cereals, grasses or weeds – and although the strainer contained a huge mass of mugwort pollen – all the rest I found was from ‘bee plants’. There is very little chance that the pollen of bee plants could have been included by accident because their pollen does not get into the air, or travel far from the parent flower. Honey, on the other hand, is rich in the pollen of plants to which bees are attracted because of their rich nectar.