[MUSIC] Okay, this lecture is about drugs, meaning of course, illegal drugs. Or to put it more correctly, drugs that are illegal under most circumstances in most jurisdictions. We can divide these illegal drugs into three different types. There are natural chemicals, mostly from plants, but also from other creatures. And typically, these have been used since ancient times. Mostly by people who you might refer to as medicine men, and they might have been used as medicines. Morphine, for instance, from the opium poppy, has been in use for millennia. Or they might be used for religious experiences. The so-called medicine men or Shamans might take the plants that contain these substances and go into some kind of hallucination and think they're communing with the spirits or with the Gods. With the advent of modern chemistry in the 19th century, it became possible to take these substances from nature and then modify them by chemical, by artificial means, to generate new compounds with different activities. And these modified natural compounds we will refer to as semi-synthetic compounds. An example of a semi-synthetic compound, which in this case is perfectly legal, would be aspirin. It's derived from a chemical that occurs naturally in willow trees. The last class are the purely synthetic compounds, and typically these compounds have been prepared in the pharmaceutical industry for disease treatment of one kind or another. And somehow, they have started to be the subject of misuse. And in this category, we might also include abuse of solvents - paint sniffing and glue sniffing. But whichever category the compounds, the chemicals, come from, they can lead to physical and psychological addiction. It's certainly nothing new. This is a quotation from Georg Steller, who was an early explorer in Siberia back in the 18th century. And as he was travelling through the wilderness of Siberia, he came across this tribe who really liked mushrooms. But they didn't like mushrooms in the way you or I might like mushrooms, maybe fried with a little red wine or garlic or something. They liked these mushrooms called the fly agarics, which they would dry and eat. And because of this chemical, ibotenic acid, that's present in the mushrooms, the people who ate them would become intoxicated and hallucinate. Now of course, these mushrooms were very popular in this tribe, so they commanded a high price, so the poor people couldn't afford the mushrooms themselves. But, according to Stellar, what the poor people would do, would be to collect the urine of the people who would have eaten the mushrooms and then drink the urine, and get the same experience, if not better. And they could do this because the body gets rid of this ibotenic acid by excreting it into the urine. It's not just mushrooms. This is the peyote cactus. It contains the chemical mescaline, which is biologically active, and this cactus has been used in various religions in Mexico for many, many years. And it spread to the Native Americans of the SouthWest United States in the 19th century and they, too, used it for religious purposes. Because of the mescaline present in the cactus, this is illegal in the United States, with the exception of those who use it for religious purposes. One of the best known drugs that have come to us from ancient times is cannabis, which as you can see, is known by many different names. So in ancient times, cannabis was well known throughout Asia, China, India, and the Middle East, and one of the uses for this plant was very simply to make rope. Hemp fibres turn out to make very good rope, and nowadays in many countries, they're used for things like bags and sacks and so forth. But certain parts of the plant contain potent chemicals that act on the brain. The first Europeans to come across cannabis were possibly the Crusaders. In the time of the Crusades, there was a mysterious organization run by the so-called Old Man of the Mountains, and this was an organization which would supply assassins. And the people who worked for this organization, according to stories that are passed down, would do absolutely anything on the orders of this Old Man of the Mountains. One theory is that they would do this because he kept them well-fed on cannabis, which is also known as hashish. And that is why we get this English word "Assassin" - it's derived from the Arabic hashish. Certainly one of the first Europeans to describe cannabis use was Marco Polo, who travelled through these regions on his trip to China. And the cannabis habit was probably first brought back to Europe by soldiers in Napoleon's army after his ill fated invasion of Egypt and Syria. In cannabis use, the typical method of ingesting it is to take the herbal material from the plant, which is cannabis sativa, and then this is usually smoked. The herbal material can be identified by using the techniques of botany. Investigators can look at the shape of the leaves, they can identify it from a characteristic smell. And a very characteristic point about cannabis leaves is the presence of small silica particles in the leaf, which can be observed under the microscope, which are called cystolithic trichomes. Cannabis sativa is the only member of its family, it doesn't have any close relatives with which it can be confused. In fact, the closest relative of the cannabis plant is the hop plant, which is used as a flavouring for beer. In addition to the herbal material, cannabis may also be consumed as cannabis resin and cannabis oil. Well, after processing, cannabis can turn up in all sort of products. Here's an example, this is cannabis flavoured chocolate, and you can see the give-away there, the leaves. And here's another example, this is cannabis flavoured vodka. Well, the biological activity of cannabis is due largely to the presence of this chemical here, delta nine tetrahydrocannabinol, and this has multiple effects upon the Central Nervous System. One thing that has been reported about taking cannabis is that the tetrahydrocannabinol appears to be effective against the very unpleasant side effects that can occur when people are taking anti-cancer drugs, that is when people are undergoing chemotherapy. The side effects of chemotherapy can be very, very unpleasant, and some people have given up their chemotherapy because of those side effects. So some people on chemotherapy have taken to smoking cannabis to get rid of those side effects. Though nowadays, synthetic alternatives are available, which do not have all the other effects of cannabis. And in some countries and some areas, it is actually now legal to consume cannabis. An example would be the U.S. State of Colorado, which has just legalized it. Well, how can cannabis be obtained? Well, either smuggled in from the country of origin or it can be grown under the right conditions.