Sex, Drugs and Chocolate: The Science of Pleasure. Paul Martin

form of medicine: when we are stressed, anxious or in pain, we seek out drugs that give us some relief; and when we are tired or depressed, we seek out stimulants to lift our mood.

      Other animals do the same, if given the opportunity. Historical descriptions of opium dens refer to mice, rats and birds sniffing the intoxicating smoke and nibbling leftover scraps of opium. Louis Lewin observed that ‘cats, dogs and monkeys inhale the smoke which their master expels from his opium-pipe, and it is said that monkeys consume the opium which oozes from the bamboo pipe’. The French writer and opium addict Jean Cocteau similarly described how flies, lizards, mice, cockroaches and spiders would gather round the opium-smoker, forming a ‘circle in ecstasy’.

      Properly conducted scientific experiments have confirmed that many species of mammals, fish and reptiles will learn to seek out and consume psychoactive drugs. When monkeys, apes, rats, cats or dogs are given free rein to self-administer drugs under laboratory conditions, they generally prefer the same drugs as humans, including alcohol, nicotine, opium, cannabis, cocaine, ether and nitrous oxide. Like humans, they will voluntarily dose themselves with recreational intoxicants, while showing little interest in psychiatric drugs such as antidepressants. And, just like us, they will work very hard to obtain the most pleasurable and addictive recreational drugs, especially cocaine. In laboratory experiments, some monkeys have willingly pressed a lever more than 12,000 times to obtain a single injection of cocaine.

      Children also display a natural propensity to experiment with altered states of consciousness. They normally achieve this without the aid of recreational drugs, using age-old techniques such as hyperventilation or spinning around to induce dizziness. Children as young as three or four will spontaneously discover the pleasures of twirling themselves into a giddy daze or hyperventilating until they almost faint. However, children soon turn into adolescents, who tend to prefer their intoxication in a chemical form such as alcohol. More than half of all 11–15-year-olds in England have drunk alcohol and more than one in five have used it within the past week.¹²

      Children’s experimentation with making themselves feel different, whether by hyperventilating or spinning around, may be a reflection of their deeper propensity to play. We are all born with an instinct to play, so that we can learn about the world around us and how to deal with it. Play behaviour is a fundamental characteristic of young humans and young animals of other species. Play is a form of safe simulation, in which the young individual can explore the world and develop their physical and mental capabilities, whilst remaining insulated from the risks that would arise from ‘serious’ versions of the same behaviour. For example, young animals play at fighting each other, or catching prey, during a stage in their development when real fighting or real hunting would be dangerous. By playing in this way, they acquire crucial physical and social skills they will need in later life. We humans play mentally as well as physically. Our attraction to temporarily altered states of consciousness might in part be a consequence of our playfulness.

Harm

      Recreational drugs provide pleasure and relief from displeasure. They also cause vast amounts of harm and suffering to individual users and society as a whole. In the UK alone, the estimated economic costs of recreational drug use are as much as £16 billion a year in terms of health care, social costs and crime.

      Addictive drugs such as heroin, nicotine and alcohol debilitate and kill people in large numbers, whether from chronic illness, overdoses or accidents. In the year 2005, for example, there were just over 1,000 deaths in England and Wales involving heroin, morphine or cocaine. Alcohol and tobacco kill far more. In the UK, where the alcohol-related death rate has more than doubled since the early 1990s, well over 8,000 deaths a year are directly related to alcohol consumption.¹³ This figure does not include the many deaths caused by alcohol-fuelled accidents, violence or vehicle crashes, neither does it include deaths from the numerous diseases for which alcohol is known to heighten the risk, such as many forms of cancer. According to some estimates, the total number of deaths to which alcohol contributes in some way may be as high as 40,000 a year in England and Wales alone. The corresponding figure for tobacco is almost three times higher, at around 114,000 deaths a year.

      Legal recreational drugs – specifically, tobacco and alcohol – cause immense damage to national health, far outstripping the effects of their less widely-used illegal counterparts. An estimated 1.5 million people in the UK are addicted to alcohol. According to government estimates, up to 17 million working days are lost each year in the UK as a result of alcohol, and its misuse costs the economy around £6.4 billion a year in lost productivity. The picture is not dissimilar in the USA, where approximately a fifth of adults abuse alcohol at some point in their life. Worldwide, alcohol is estimated to be responsible for about 4 per cent of the global disease burden.

      Most victims of alcohol abuse die from liver disease, heart disease, accidents or acute alcohol poisoning. Most of those with alcohol-induced liver disease are social drinkers, not alcoholics. They may not even think of themselves as having a drink problem. In England, the number of cases of alcohol-related cirrhosis of the liver almost tripled over the period between 1996–7 and 2005–6. Doctors are now encountering patients in their twenties with end-stage cirrhosis of the liver, a condition that usually develops only after years of hard drinking. Alcohol heightens the risk of many forms of cancer, including cancers of the mouth, liver and oesophagus. It may also increase the risk of breast cancer in women with a family history of the disease. Research has found that the sisters and daughters of women with breast cancer are themselves at greater risk of developing breast cancer if they drink alcohol daily.

      In the UK, as elsewhere, thousands of people die every year in road traffic accidents where alcohol has been a contributory or causal factor. Thousands more die or are seriously injured in alcohol-fuelled violence and domestic accidents. Alcohol is involved in more than half of all visits to hospital accident and emergency departments and orthopaedic admissions, and is a factor in about a third of all arrests made in urban police stations. In larger doses, it is capable of killing directly. On average, one person dies each day in England from acute alcohol poisoning. The typical victim is a young person who has been celebrating with friends. Alcohol kills by suppressing the brain circuits that control breathing and the cough reflex; the victims of alcohol poisoning often die from lack of oxygen or because they inhale vomit into their lungs, causing respiratory failure.

      Sexual crime is another, often underestimated, risk from alcohol. Every year, women and men are raped while incapacitated by alcohol. They often believe their drink must have been spiked with a date-rape drug such as Rohypnol, although the evidence suggests that this may be less common than often assumed. A 2006 study by the UK Association of Chief Police Officers found that only one in ten cases of alleged sexual assault was suspected of being drug-assisted. None of these cases involved Rohypnol and only a few involved another date-rape drug (GHB), whereas almost all of the date-rape victims said they had been drinking, some of them heavily. The most common method of spiking drinks is with more alcohol. It is likely that some of the rape victims who thought they had been drugged had in fact been very drunk.

      As to tobacco – well, I won’t bore you by rehearsing all the baleful statistics about the toll of death and disease for which it is responsible, though I will mention an authoritative analysis which calculated that a regular smoker will reduce their life expectancy by an average of ten years. This startling statistic reinforces the point that smoking is the most dangerous thing that most people will ever do in their lives. It remains the biggest single cause of preventable death on the planet. Between them, alcohol and tobacco – those legal recreational drugs we can buy in the high street – account for approximately 90 per cent of all drug-related deaths in the UK. They are also among the leading contributors to disease and premature death worldwide.

      Cannabis, the most popular of the illegal recreational drugs, used to enjoy a reputation for being relatively safe. But that reputation has been eroded in recent years, as a growing body of evidence has linked it with a range of medical risks. The most serious concerns have arisen from research indicating that cannabis can increase the severity of existing psychotic