The year is 2350 and humanity is divided into a genetically enriched elite and an educationally deprived lumpen mass who cannot even breed successfully with their gene-enhanced betters. Lee Silver believes this is not science fiction

The date is May 15 2350 and the place Washington DC. The United States still exists as a unified country, but its population is very different from the one alive 350 years earlier. The most striking difference is that the extreme polarisation of society that began during the 1980s has now reached its logical conclusion, with all people belonging to one of two classes. The people of one class are referred to as Naturals, while those in the second class are called the Gene-enriched or simply the GenRich.

These new classes of society cut across what used to be traditional racial and ethnic lines. In fact, so much mixing has occurred during the past 300 years that sharp divisions according to race - black versus white versus Asian - no longer exist. Instead, the American populace has finally become the racial melting pot that earlier leaders hoped for. The skin colour of Americans comes in all shades from African brown to Scandinavian pink, and traditional Asian facial features are present to a greater or lesser extent in a large percentage of Americans as well.

But while racial differences have mostly disappeared, another difference has emerged that is sharp and easily defined. It is the difference between those who are genetically enhanced and those who are not. The GenRich - who account for 10 per cent of the American population - all carry synthetic genes; genes that were created in the laboratory and did not exist within the human species until 21st century reproductive geneticists began to put them there. The GenRich are a modern-day hereditary class of genetic aristocrats.

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Some of the synthetic genes carried by present-day members of the GenRich class were already carried by their parents. These genes were transmitted to today's GenRich the old-fashioned way, from parent to child through sperm or egg. But other synthetic genes are new to the present generation. These were placed into GenRich embryos through the application of genetic engineering techniques shortly after conception.

The GenRich class is anything but homogeneous. There are many types of GenRich families, including GenRich athletes who can trace their descent back to professional sports players from the 21st century. Embryo selection techniques have been used to make sure that a GenRich athlete has received all of the natural genes that made his unenhanced foundation ancestor excel. But in addition, at each generation beyond the foundation ancestor, sophisticated genetic enhancements have accumulated so that the modern-day GenRich athlete can perform in a way not conceivable for any unenhanced Natural. Of course, all professional baseball, football, and basketball players are special GenRich subtypes. After 300 years of selection and enhancement, these GenRich individuals all have athletic skills that are clearly "non-human" in the traditional sense. It would be impossible for any Natural to compete.

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Another GenRich type is the GenRich scientist. Many of the synthetic genes carried by the GenRich scientist are the same as those carried by all other members of the GenRich class, including some that enhance a variety of physical and mental attributes, as well as others that provide resistance to all known forms of human disease. But in addition, the present-day GenRich scientist has accumulated a set of particular synthetic genes that work together with his "natural" heritage to produce an enhanced scientific mind. Although the GenRich scientist may appear to be different from the GenRich athlete, both GenRich types have evolved by a similar process. The foundation ancestor for the modern GenRich scientist was a bright 21st-century scientist whose children were the first to be selected and enhanced to increase their chances of becoming even brighter scientists who could produce even more brilliant children. There are numerous other GenRich types including GenRich businessmen, GenRich musicians and GenRich artists who all evolved in the same way.

Not all present-day GenRich individuals can trace their foundation ancestors back to the 21st century, when genetic enhancement was first perfected. During the 22nd and even the 23rd centuries, some Natural families garnered the financial wherewithal required to place their children into the GenRich class. But with the passage of time, the genetic distance between Naturals and the GenRich has become greater, and now there is little movement up from the Natural to GenRich class. It seems fair to say that society is on the verge of reaching the final point of complete polarisation.

All aspects of the economy, the media, the entertainment industry, and the knowledge industry are controlled by members of the GenRich class. GenRich parents can afford to send their children to private schools rich in the resources required for them to take advantage of their enhanced genetic potential. In contrast, Naturals work as low-paid service providers or as labourers, and their children go to state schools. But 24th-century state schools have little in common with their predecessors from the 20th century. Funds for state education have declined steadily since the beginning of the 21st century, and now Natural children are only taught the basic skills they need to perform the kinds of tasks they will encounter in the jobs available to members of their class.

There is still some intermarriage as well as sexual intermingling between a few GenRich individuals and Naturals. But, as one might imagine, GenRich parents put intense pressure on their children not to dilute their expensive genetic endowment in this way. And as time passes, the mixing of the classes will become less frequent for reasons of both environment and genetics.

The environmental reason is clear enough: GenRich and Natural children grow up and live in segregated social worlds where there is little chance for contact between them. The genetic reason, however, was unanticipated.

It is obvious to everyone that with each generation of enhancement, the genetic distance separating the GenRich and Naturals is growing larger and larger. But a startling consequence of the expanding genetic distance has just come to light. In a nationwide survey of the few interclass GenRich-Natural couples that could be identified, sociologists discovered an astounding 90 per cent level of infertility. Reproductive geneticists have examined these couples and come to the conclusion that the infertility is due primarily to an incompatibility between the genetic makeup of each member.

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Evolutionary biologists have long observed instances in which otherwise fertile individuals taken from two separate populations prove infertile when mated to each other. And they tell the sociologists and the reproductive geneticists what is going on: the process of species separation between the GenRich and Naturals has already begun. Together, the sociologists, the reproductive geneticists, and the evolutionary biologists are willing to make the following prediction: if the accumulation of genetic knowledge and advances in genetic enhancement technology continue at the present rate, then by the end of the third millennium, the GenRich class and the Natural class will become the GenRich-humans and the Natural-humans - entirely separate species with no ability to cross-breed, and with as much romantic interest in each other as a current human would have for a chimpanzee...

If you think you have just read a piece of science fiction with no basis in reality, think again. Genetic engineering is already used routinely on laboratory animals, and recent advances in cloning and artificial chromosome technology make it almost certain that the technology will be transferable to humans. Many scientists have assumed this will indeed be the case, and some have discussed the effects this could have on a society of the near-future. But what has come across less clearly are the consequences further down the road, as genetic enhancements accumulate from one generation to the next.

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Cumulative genetic processes often have a way of taking us by surprise. There were ape-like animals living five million years ago in Africa who had children that went on to evolve along two different lines into human beings and chimpanzees. Nowhere along those lines of a million generations did any child appear to be very different from its parents. And yet at the beginning there was an ape; at the end of one line, there was a human being.

Spectacular changes occurred even more rapidly when early humans consciously intervened in the cumulative process. Within a hundred generations, we took individuals from a single species of grey wolf and bred them down different pathways into French poodles and St Bernards, into hounds and sheep herders, and into so many other breeds that look and behave so differently it is hard to believe they are all distant cousins of each other. Incredibly, the breeding of dogs was performed by people who did not even understand the laws of genetics, let alone the function of individual genes.

The self evolution of humans will operate under different principles. Within a decade, we will have identified and characterised each of the 100,000 genes that a human carries in his or her cells. And within a decade or two after that accomplishment, the increasingly powerful tools of biotechnology will allow us to decipher the function of each of these genes. Of course, just because a technology becomes feasible does not mean that it will be used. Or does it? Society, acting through government intervention, could outlaw any one or all of the reprogenetic practices that I have described. Isn't the non-use of nuclear weapons for the purpose of mass destruction over the past half century an example of how governments can control technology?

There are two big differences between the use of nuclear technology and reprogenetic technology. These differences lie in the resources and money needed to practise each. The most crucial resources required to build a nuclear weapon are tightly controlled by the government itself. The resources required to practise reprogenetics - precision medical tools, small laboratory equipment, and simple chemicals - are all available to anyone with the money to pay for them. The cost of developing a nuclear weapon is billions of dollars. In contrast, a reprogenetics clinic could easily be run on the scale of a small business anywhere in the world. Thus,even if restrictions on the use of reprogenetics are imposed in one country or another, those intent on delivering and receiving these services will not be restrained.

In Brave New World, Aldous Huxley envisioned a future worldwide political state that exerts complete control over human reproduction and human nature as well. In this brave new world, the state uses foetal hatcheries to breed each child into a predetermined intellectual class that ranges from alpha at the top to epsilon at the bottom. Individual members of each class are predestined to fit into specific roles in a soulless utopia.

While Aldous Huxley guessed right about the power we would gain over the process of reproduction, I think he was dead wrong when it came to predicting who would use the power and for what purposes. What Huxley failed to appreciate was the driving force behind babymaking. It is individuals and couples who want to reproduce themselves in their own images. It is individuals and couples who want their children to be happy and successful. And it is individuals - not governments - who will seize control of the new reprogenetic technologies. They will use some to reach otherwise unattainable reproductive goals, and others to help their children achieve health, happiness, and success. And it is in pursuit of this last goal that the combined actions of many individuals, operating over many generations, could perhaps give rise to a polarised humanity more horrific than even Huxley could imagine.

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Lee M. Silver is a professor of genetics at Princeton University and author of Remaking Eden, Cloning and Beyond in a Brave New World, Weidenfeld and Nicolson, Pounds 20.