Equality is one of the most sacred values of modern society. Yet modern society is poised to become the most unequal in history. For humankind might soon split into biological castes, with upper-class humans transformed into gods.

When we think about the future, we generally think about a world in which people like us enjoy more advanced technology: spaceships that travel at the speed of light, powerful laser guns, intelligent robots. But the most important potential of future technologies such as genetic engineering and brain-computer interfaces lies in the possibility of altering our own bodies and minds, rather than just our vehicles and weapons. If elites have preferential access to such technologies, the result may well be the translation of social inequality into biological inequality. For the first time in history, the upper classes will be not only richer than the rest of humankind, but also much more talented, beautiful, courageous -- or any other trait they would care to buy.

When scientists are confronted with such scenarios, their standard reply is that in the twentieth century, most medical breakthroughs began with the rich, but gradually trickled down to the general population. We can expect this to happen again in the twenty-first century. Yet this may well be just wishful thinking. What happened in the twentieth century may not necessarily repeat itself in the twenty-first century, for two important reasons.

First, medicine is undergoing a conceptual revolution. Twentieth-century medicine aimed to heal the sick. In contrast, twenty-first-century medicine is increasingly aiming to upgrade the healthy. Healing the sick was an essentially egalitarian project, because it assumed that there is a normative standard of physical and mental health that everyone can and should enjoy. But upgrading the healthy is an elitist project, because it rejects the idea of a universal standard applicable to all, and it seeks to give some individuals an edge over others. If some upgrade becomes so cheap and common that everyone enjoys it, it will simply be considered the new norm, which the next generation of treatments will seek to surpass.

Secondly, the world is undergoing a dramatic military and economic transformation. The twentieth century was the age of the masses. Armies needed masses of healthy soldiers, and the economy needed masses of healthy workers, which is why medicine focused on treating the masses. The greatest medical achievements were in the fields of mass hygiene, mass vaccinations and overcoming mass epidemics. The rich had an interest in vaccinating the poor and building hospitals and sewage systems in the slums because if a country wanted to be a great power, it needed many millions of healthy soldiers and workers.

But the age of the masses may be over and with it, the age of mass medicine. Armies are no longer based on recruiting millions of soldiers, but rather on small numbers of experts and cutting-edge technologies such as pilotless drones. In the economic sphere, algorithms are replacing humans not only in simple manual jobs, but also in those demanding higher cognitive abilities, such as driving taxis, trading on the stock exchange or diagnosing diseases.

As the twenty-first century unfolds, normal humans are in danger of losing their economic value because intelligence is decoupling from consciousness. Until today, high intelligence always went hand-in-hand with a developed consciousness. Only conscious beings could drive taxis or diagnose diseases. Therefore every conscious human was potentially an economic asset.

However, today we are developing new types of non-conscious intelligence that can perform these tasks far better than humans. This raises a novel question: which of the two is really important -- intelligence or consciousness? From an economic perspective, the answer is clear: intelligence is mandatory but consciousness has little value. Once the economy enjoys the services of highly intelligent non-conscious algorithms, normal humans might become worthless.

In a world in which normal humans are losing their military and economic value, elites around the world may conclude that there is no point in providing normative conditions of health for masses of poor people, and it is far more sensible to focus on upgrading a handful of superhumans beyond the norm. This would especially apply to huge developing countries like India, China and Brazil. These countries resemble a long train. The elites in the first class cars enjoy healthcare, education and income levels which are on a par with the most developed nations in the world. However, the hundreds of millions of ordinary citizens who crowd the third class cars still suffer from widespread diseases, ignorance and poverty.

What would the Indian, Chinese or Brazilian elite prefer to do in the coming century? Invest in fixing the problems of hundreds of millions of poor -- or in upgrading a few million rich? In the twentieth century, the elites had a stake in fixing the problems of the poor, because they were militarily and economically vital. Yet in the 21st century, the most efficient (and ruthless) strategy may be to let go of the useless third class cars, and dash forward with the first class only. In order to compete with South Korea or Canada, Brazil might need a handful of upgraded superhumans far more than millions of healthy ordinary workers.