Science can be a little scary. Its potential to transform life itself has led to predictions that we might re-write our own genetic make-up or merge our minds with machines. But 2007 will show that it is not these sci-fi possibilities that are of immediate concern. Real possibilities of changing our human nature are creeping up from a less obvious direction. More and more drugs developed to treat disease are turning out also to offer the potential to “enhance” the cognitive powers of healthy people, and to push human life expectancy much further, perhaps to 115 years and beyond.

The potential to alter our nature and lifespans elicits strong reactions. The transhumanists—a loose coalition of scientists, technologists and thinkers who seek opportunities to enhance the human condition—see change as desirable. Human nature, says Nick Bostrom, an Oxford University philosopher and advocate of transhumanism, is “a work in progress, a half-baked beginning that we can learn to remould in desirable ways…we shall eventually manage to become posthuman, beings with vastly greater capacities than present human beings have.” Others argue that we will never have sufficient wisdom to make ourselves more than we are. Francis Fukuyama of Johns Hopkins University describes transhumanism as one of “the world's most dangerous ideas”. But whatever you may think, the possibilities for changing your nature by direct biochemical intervention are arriving now.

There is no greater goal for transhumanism than the conquest of death. Some of the most controversial advocates of technological improvements to humans, including Ray Kurzweil, an American inventor and author, and Aubrey de Grey, a gerontologist and chairman of the Methuselah Foundation, argue optimistically that immortality may become achievable for people who are alive today. But even without the yet-to-be-invented technologies that they say will make this possible, there are good reasons why we can hope to live a lot longer.

Transhumanists question the conventional wisdom that the human lifespan is coming to a natural limit. History shows that every limit announced by experts is quickly overturned. Back in 1928, an American demographer, Louis Dublin, calculated that the upper limit on average life expectancy would be 64.8 years, a daring figure at the time, with American life expectancy then just 57 years. But now his figure looks timid, given that life expectancy for women in Okinawa, Japan, has passed 85.3 years, 20 years more than Dublin claimed possible. Also looking timid are the scientists who later predicted that life expectancy would nowhere pass 78 years (in 1952), 79 years (1980) and 82.5 years (1984).

Can this steady rise in life expectancy be replaced with a giant leap? Many transhumanists think so. We already know that cutting back severely on calories in the diet can give life expectancy a remarkable boost—between 30% and 50%—in a range of animals. Now evidence is emerging not only that this approach may work in humans but also that drugs may provide the benefits of calorie restriction without the pains of the diet.

Life-extension enthusiasts who have been eating just 1,800 calories a day for an average of six years (a healthy Western diet averages 2,700 calories a day) do indeed show signs that their bodily ageing is slowing. Eating far fewer calories does not simply slow metabolism, nor do the advantages come just from being thin, as aggressive calorie-burning exercise does not confer the same benefits. Rather, calorie restriction appears to trigger natural defences designed to boost the chances of survival during periods of food scarcity. As many of those defensive responses are co-ordinated by a set of genes called sirtuins, there is a chance that drugs can be used to trigger their action directly, without the diet. Chemicals that affect sirtuin activity have been found in plants and one, resveratrol, extends lifespan in test animals. In one species of fish, maximum lifespan increased by almost 60%. Humans will be pleased to know that resveratrol occurs naturally in red wine

Efforts to develop sirtuin-targeting drugs and test them for clinical safety are under way, but the companies working on them stress a goal of activating “health-promoting genes”, rather than life-extension itself. That is just too controversial.

The same is true of other drugs that may enhance human capabilities. Modafinil provides an interesting example. The drug was developed to treat narcolepsy and sleep problems but is a hit with healthy people who want to improve their concentration and skip sleep. Modafinil users dramatically improve their ability to solve classic tests of planning ability, like the Tower of London task where sets of coloured discs on pegs have to be moved from one pattern to another in the fewest moves. More than 40 other cognitive enhancement drugs are under study around the world.

Numerous drugs are also in development that may enhance or alter memory. In the brain, memories are coded in patterns of links between nerve cells and are laid down in two stages: the first when the strength of signals between cells is temporarily enhanced and the second when memory is consolidated through the synthesis of new proteins. Ampakine drugs target the first stage, boosting excitatory communication between nerve cells, as well as stimulating brain growth. Results are encouraging, at least for middle-aged rats. Recently scientists found that the drug turned back the clock for a key measure of decline in memory function.

Another drug, propranolol, has the quite different aim of weakening troubling memories. Memories are etched with particular strength in stressful situations, including wars, car accidents and rapes. Later these memories can return as a painful part of post-traumatic stress disorder. Propranolol blocks the impact of stress hormones on memory formation and, if taken very soon after the trauma, turns down the intensity of recall. More surprising is a new drug called ZIP (Zeta Inhibitor Peptide) that makes rats forget everything they learnt recently, without affecting their learning ability. ZIP has not been tested in humans but has the potential to wipe out all new memories.

In one species of fish, maximum lifespan increased by almost 60%

Transhumanists have been quick to debate where such drugs might lead: not only might they lessen stress disorders, but they could also remove the feeling of guilt by lessening memories of wrongdoing, or dull the pains of love lost. Such possibilities highlight the problems of playing with human nature. We may be more efficient, but without the feelings of others around us.

That leaves us with the great unresolved debate in transhumanism: whether, if we choose to “enhance” ourselves, we can say we are the same person afterwards, and whether that matters. But one thing is certain: whatever ailment drugs may be developed to treat, if they can also be used to provide someone with a competitive advantage, or prolong life, people will take them.





Alun Anderson: senior consultant, New Scientist