On 6th December 2004 a baby girl named Yan was born. Her father, an internet entrepreneur, is called Shen Tong. Yan was Shen’s first child, and you might have expected him to have an excitable, sleepless night. But oddly the opposite occurred. He slept better than he had done for 15 years, six months and two days. It’s possible to be exact about the timing because 15 years, six months and two days earlier was 4th June 1989 and on that day Shen had been on a boulevard just off Tiananmen Square in Beijing. He was a 20-year-old student, and like thousands of others he was demonstrating in favour of political reform.

After martial law was declared, Shen watched as the army drove through the city. Between outbursts of shooting, students tried to reason with the military. Shen approached a truckload of soldiers; he wanted, he says, to calm the surrounding crowd. Suddenly an officer pulled out a pistol. Parts of the rest of the story are hazy. Shen was dragged back by others. A shot was fired, and a female student, roughly Shen’s age and standing just behind him, was hit in the face. She died. Shen remembers her covered in blood. He is convinced that the bullet was intended for him. Shen moved to the US, but violent images recurred in his dreams for many years—until, that is, the arrival of Yan. Not only did he sleep well that night, but the following night, and the night after that.

Post-traumatic stress disorder (PTSD) is a condition that can occur after a distressing event. It involves a traumatic memory which comes back to mind repeatedly and involuntarily. It’s associated with chronic anxiety and hyper vigilance. The numbers affected are contentious. By one mid-range estimate tens of thousands of US veterans of Iraq and Afghanistan suffer from it. As do British veterans of the Falklands war—more of whom have committed suicide than died in active service. The Pentagon has sunk hundreds of millions of dollars into PTSD research. But of course, as Shen Tong knows, you don’t have to be a soldier to experience it.

Investigation of PTSD has been an important cause of new research into memory. And our understanding of memory is, in turn, propelling a debate about what is known as enhancement, or the boosting of human capacities beyond a normal level. The first issue to emerge was physical enhancement, such as doping in sports and mood enhancement with drugs like Prozac. Then came varieties of cognitive enhancement, as aids to concentration like Ritalin or newer “neuroenhancing” drugs like Adderall which are used by stressed students or harried office workers. Most contentiously, scientists now see possibilities to modify our moral character, using neurological techniques to make us ethically better—or perhaps worse (See box p44). And the latest research holds out the promise of drugs to help forget traumatic memories, or even to stay devoted to our sexual partners. Many people—notably some religious leaders, doctors, scientists, politicians and philosophers—have misgivings about much of this. But when they spell out their qualms, their reasoning is often shakier than it first appears. Nonetheless, this is not a debate we can ignore. What scientists are now discovering about memory presents us with an interesting set of dilemmas.

Our understanding of memory is in its infancy, but developing fast. We know that the hippocampus (the size of a little finger and so-called because it loosely resembles a sea horse) is the area of the brain that is thought to consolidate memory and place facts in context. We know too that the almond-shaped amygdala is the Clapham Junction of the brain’s emotional system. (People who have damage to the amygdala don’t even flinch if a gun is held to their head.) The amygdala provides signals to the hippocampus about which memories it is important to store. The more intense the emotional arousal in the amygdala, the more likely a memory is to be retained.

There’s an obvious evolutionary reason for humans to have excellent recall of scary situations. But with PTSD sufferers the brain’s warning system has, as it were, short-circuited, or over-reacted. A soldier who witnesses a comrade shot in a trench beside him might have a fearful memory when he next sees or hears a gun. A person with PTSD will experience the same anxiety routinely, and often when the connection is far more tenuous—whenever he sees mud, or a hole in the ground, for example, but perhaps too as he dozes off to sleep.

A pharmaceutical treatment is close. Some time ago researchers discovered that if subjects took propranolol, a beta-blocker, within a few hours of a traumatic episode, it reduced the likelihood of their developing PTSD. This was a fascinating finding, but given the need to administer the drug so quickly, of limited practical use (unless soldiers carry a supply with them). More recent studies suggest that propranolol can assist even those who have suffered from PTSD for years.

Memory specialists use this analogy to explain the drug’s impact. Imagine that you order a book in a library. The book is collected from the stacks. If you read it by an open window with the sun streaming in, the book will be slightly bleached. When you return it, what is stored is a fainter copy. Propranolol operates as fierce bleaching sunlight. If subjects with PTSD are prompted to conjure up an unwelcome recurring memory while being injected with the drug then the memory is re-filed in the brain in a weakened state. Fewer nightmares, less anxiety: an effect similar, some think, to the way that the emotional impact of his child’s birth may have metaphorically shone bright rays on Shen Tong’s ghastly dreams.

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The first mouse completed its swim in eight seconds. It wasn’t exactly the Michael Phelps of the rodent world, but Peter Giese looked impressed. The second mouse was far slower, though at 21 seconds still well above average. Both animals were frantically circling a pool about two metres in diameter, their paws flapping rapidly but ineffectively. A camera tracked them, producing a map of their journeys on a screen in the corner of the room. Mice dislike water. But in one section of the pool was a tiny platform: once they found it they could clamber aboard. To help them detect it objects were attached to the room’s walls—an orange chair to our left, two footballs to our right. If the mice looked up, they could use these as visual aids to orient themselves. Finding the platform was not easy, however, especially as half the animals had been genetically modified. They were, in effect, Alzheimer’s mice, created with too much amyloid-peptide, the protein that causes the disease.

We were in the basement of a medical research block of King’s College London. Here Giese, an affable middle-aged German-born professor, was testing another new memory drug. It had already been found to be effective in chicks. Mice, which are biologically closer to humans, were the next stage of investigation. The drug appeared to combat the worst effects of amyloid-peptide, although it is not yet clear why, or how. The point of the experiment was to see whether mice, when injected with the new drug, would locate the platform more quickly. Giese was cagey about the findings but it seemed as if his research team had encouraging results. The implications are immense—the cost to society of memory disorders is inestimable, affecting not just those with Alzheimer’s but sufferers from schizophrenia, depression and PTSDs.

Much memory research has been driven by the hope of curing illness that causes memory to operate at below a normal level. But restoring normal memory may also provide the key to memory enhancement for the healthy too. Our ability to learn is closely linked, of course, to our ability to memorise. In the not too distant future Giese believes there will be memory pills—mental Viagra, he calls it—that will help the many elderly people who experience memory loss. Within three decades, he thinks, there will be cognitive enhancers on the market that develop standard skills, such as mastering a foreign language. “I’m sure you’ll be able to go to the store and buy one of them, and learn French more quickly.”

We would all welcome a cure for Alzheimer’s. And if it’s a good thing to prevent memory deterioration, why should we not also embrace memory enhancement? In the media, enhancement breakthroughs inevitably lead to warnings that scientists are playing God or creating brave new worlds. But finding a rational objection, one not based on a gut reaction of repugnance, isn’t easy. The premise of the pro-enhancers is seductive: the world would be a better place if people became smarter and happier—so long as they’d chosen to become so.

Hostility to this idea is widespread. For instance, some disability rights campaigners resent that the enhancement debate implies that there are superior and inferior human beings. Many religious leaders oppose enhancement research on stem cells and embryos. But the most sustained recent critique has been delivered by Harvard philosopher Michael Sandel, this year’s Reith lecturer. During the Bush years Sandel served on the President’s Council on Bioethics—and his academic credentials combine with a flair for communication to make him an influential figure in this field.

Biomedical technologies hold out the prospect that we can make our children taller, more musical, or faster on the athletics field. But it’s a drive towards perfectionism that Sandel urges us to resist. He wants us to appreciate what he calls the “gifted” character of human powers and achievements. It’s hubristic, he says, to try to exert dominion over all of nature, including human nature. Parents love their offspring for who they are. There’s a contingency to how children turn out, a fact that’s integral to the sort of parental love we admire.

The value of contingency does not just apply to one’s offspring. Among Sandel’s illustrations is sport. It might, for a time, be enthralling to watch a biologically souped-up baseball player whack every pitch for a home run but, predicts Sandel, we’d soon tire of it as “our admiration for the achievement shifts from the player to the pharmacist.” And underlying this shift is our desire to see the display of “natural” human gifts that might involve hard work and training but not the short cut of an injection or a gene manipulation.

One difficulty with Sandel’s position is that it’s not clear there would be a unanimous response to his baseball thought experiment. Some of us might delight in watching a football game between 22 Rooneys and Ronaldos, while listening to an orchestra of enhanced musicians could prove a sublime experience. It is a point made by a prominent opponent of Sandel, Allen Buchanan of Duke University. In a series of lectures at Oxford in spring 2009, Buchanan pointed out that bioengineering would not necessarily replace sweat and grind. It certainly hasn’t yet. Take the case of US baseball player Barry Bonds, embroiled in a steroid abuse scandal. Bonds is alleged to have taken drugs to follow a gruelling training regime: he was not avoiding graft, but enabling it.

There’s also the tricky distinction between natural and non-natural enhancements, which can be a little blurry—as even Sandel acknowledges in his book, The Case Against Perfection. Runners are allowed to increase their speed by wearing trainers, or through diet and training. What, then, about altitude training, which boosts the production of red blood cells—which carry oxygen? Perhaps that seems acceptable too. But is there any ethical difference between flying to Mexico to train and undergoing a blood transfusion that produces the same physiological result? (The practice is now illegal, but it wasn’t in the 1970s when blood-doping rumours pursued long-distance runner Lasse Viren.) Or indeed, between this and sealed “altitude houses” which simulate thin air and in which athletes can sleep? Nor can any clear-cut line be sliced between enhancement and treatment. With laser surgery, a person who wanted to remedy their shortsightedness may emerge from the operation with far better vision than average. But should Olympic archers be allowed to undergo this treatment? And, were it possible to reverse memory loss, would it be acceptable to give a patient far greater power of recall than he or she had before?

Other objections to enhancement seem just as problematic. It’s said that it will lead to a growing gap between those who can afford it and those who can’t—an empirical claim and one that needs to be monitored and, if true, addressed. But problems of equality are not unique to enhancement. And evidence so far suggests that drugs that boost cognition may be an egalitarian force. Intriguingly, many studies have shown that neuroenhancing drugs are less effective for those with above average capability. Pro-enhancers—who include not only thinkers like Buchanan but, more pertinently, pharmaceutical companies eyeing lucrative new markets—believe that use of such drugs will spread in the same way as mobile phones: initially expensive toy-gadgets for the rich and within a few years dispersed through society and across nations.

Then there’s the precautionary principle. This flags a warning: we should be careful with this stuff. Bioengineering can effect change with great power and speed—and set in train irreversible transformations, the consequences of which we cannot predict. And this is clearly a sensible concern; Buchanan says that we need to worry “about the unwitting disruption of benign interdependencies,” by which he means that we may tinker with one cognitive ability and inadvertently botch up another. But while Buchanan acknowledges the danger he also highlights another risk; that we underestimate the benefits of society where people can become cleverer, better at making choices, more productive and happier.

At the heart of the debate there remains unease about tampering with the very things that make humans human. And while we are becoming accustomed to some varieties of enhancement, our capacity to manipulate not just our bodies and our cognitive faculties, but potentially also our core emotions, is taking us into a world of dizzyingly new options. Take sex and love, for instance. If you want to know about the birds and the bees, a good place to start is the vole. To the human eye, these rodents, with their stout bodies and hairy tails, are not the most attractive creatures in the animal kingdom. But fortunately for the survival of their species the male and female prairie vole seem to rub along pretty well. So well, that, most unusually, these animals remain sexually faithful to each other for the duration of their short lives.

The prairie vole has a close cousin called the meadow vole. It looks almost identical but differs in one particular: the male meadow vole is highly promiscuous. It’s this peculiarity that has led the social neurobiologist Larry Young of Emory University to devote the last 15 years of his life to studying voles. He discovered that when prairie voles mate, a hormone called vasopressin is released, and that the cells that respond to the vasopressin—the receptors—are located in the pleasure areas of the vole brain. The vole sees its mating partner as the cause of the pleasure, and thus a bond between the pair is formed. For meadow moles, however, the receptors are in a different part of the brain, so there isn’t the same pair-forming impact of mating. But by introducing a single new gene, one that influences vasopressin receptors, Young’s team managed to change the male meadow voles into loyal lovers.

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When it comes to love and sex, humans and voles seem to have a lot in common. A study in 2008 of Swedish twin brothers found that differences in the way that the hormone vasopressin was absorbed correlated strongly with how well each man fared in marriage, assessed by levels of infidelity and divorce. One day we may demand our partners test for the hormone, or farther on in the future, even use gene therapy to foster sexual fidelity (surely an enhancement that the church would approve?).

In a 2008 paper Anders Sandberg and Julian Savulescu of Oxford’s Uehiro Centre for Practical Ethics somewhat clinically divide erotic love into three parts. After lust (seeking sexual union with any appropriate partner), comes attraction (choosing and preferring a partner), followed by attachment (staying together). Each stage is associated with a brain system that can be modulated by chemical stimuli, for example, lust by testosterone, and attachment by entactogens. If we want to encourage long-term relationships—and the empirical evidence is that they lead to health and happiness—then must we conclude, as Sandberg and Savulescu do, that “we should use our growing knowledge of the neuroscience of love to enhance the quality of love by biological manipulation”? Not necessarily. This is where concerns about human nature, identity and authenticity creep in. How should we feel about a flagging relationship kept alive through chemical infusions? Whatever your answer Savulescu says it is paternalistic to deny individuals the right to decide. “I’m not the diviner of what true love is. It’s up to people to make decisions about how to use these technologies to benefit their relationships.”

We are in the midst of a revolution in biotechnology and there will soon be a cornucopia of enhancement pills on sale. How far this requires a revolution in our moral thinking is a moot point. It is already common for American students to boost their exam performance with drugs like Adderall or Provigil. But the writing of this article has been fortified by a more traditional enhancer—caffeine. While we may blanch at the idea of love potions, a more traditional fluid has lubricated many first dates, and lowered inhibitions—alcohol.

What’s new is the power and effectiveness of the drugs. But speaking after his experiment with the swimming mice, Peter Giese took some comfort in one of his laboratory findings: an improvement in one area of cognition sometimes appears to lead to a decline in another. Evolution, he thinks, has so optimised the brain that its capacities operate in a fragile equilibrium. His team has engineered ordinary mice to learn quicker and better, but these bionic creatures are less able to apply their knowledge flexibly. However, as Giese acknowledges, some of us may be willing to make these kind of trade-offs.

One day, in theory, science may crack the trade-off problem. It may be feasible to strengthen one capacity with minimal or no cost to another. Even so, enhancement will never automatically equate to improvement. An ability to delete or weaken selective memories is a blessing to those incapacitated by PTSD. But would we want armies in which no soldier would suffer trauma from conflict? For society, the moral dilemmas thrown up by the biomedical breakthroughs are acute. And the pace of scientific change is far outstripping public debate. We have yet to get a firm grip of the slippery concepts of human nature, and the linked notions of identity and authenticity. On an individual level, though, the choice can be straightforward. “Memory is a very curious thing,” says Shen Tong. What if he had been offered the memory-weakening pill and guaranteed its safety? “Oh yes, I’d have taken it.”

Moral enhancement: a question of trust

Economists use a game of trust to reveal our moral intuitions. Person A and Person B are both given £12. Person A is the depositor, Person B the trustee. Person A can choose how much to deposit with Person B: nothing, £4, £8 or £12. When the money is transferred it immediately triples in value. Thus, if Person A gives Person B £8, she is left with £4, while Person B now has 3×8 + 12 = £36. Person B can then choose to give as much back to Person A as he thinks appropriate. If he were to give back £20, say, he would still be left with more than he began. But he could hand over all £36 or nothing at all.

This game has been used to show that humans are not entirely rationally self-interested. But for our purposes what is interesting is this: when subjects are given the hormone oxytocin they are more likely to hand over a larger share of their money, exhibiting greater trust that the other person will treat them fairly. Boosting oxytocin levels is not a high-tech procedure; the hormone can be delivered by nasal spray. Trust is central to our personal and business relationships, and altering trust levels could alter society in a profound way.  Enhancement is not identical to improvement. Pumping oxytocin through the air-conditioning could be used for less noble purposes: companies manipulating their consumers, politicians their voters, or predatory men their dates.