If demographics is destiny who will run the century?

Most of Europe, and even China, will face a dearth of young workers soon. What does this mean for the rest of the world?

A consensus is growing that America has become like Britain after 1945, destined for inevitable decline. Many reasons are given to support this view: the burden of debt; the sclerotic politics of Washington; the cost of supporting old people as they live longer; the inability to compete with China. A timely counterblast to this defeatist talk has come from Joel Kotkin, a California-based expert on cities and demography, who predicts that America's genius for attracting and absorbing talented immigrants will keep it a global powerhouse for generations to come.

His book, The Next Hundred Million: America in 2050, is based on the projection that America's population will rise to 400 million by midcentury. It was 200 million in 1967 and 300 million in 2006. Mr Kotkin has been pilloried by some liberals for excess of optimism. They believe that an extra 100 million people would strain the country's institutions and exhaust the environment and water resources. On the right, there are questions as to how whites will tolerate becoming a minority in their own country by 2050, as is widely predicted.

These are good questions, but Mr Kotkin has history on his side against the decline-ists. In the 1960s, America feared it would be overtaken economically by the Russians. In the 1980s it was the Japanese, and now China is tipped as the victor. Predictions are rarely correct, but Mr Kotkin's focus on demography provides a useful gauge of the vitality of nations. The Russians, the rump of the former superpower, are in intensive care. Every year Russia has some 800,000 fewer schoolchildren. In 1997 there were 26 million children and teenagers at school. When the new school year begins next September, there will be only 15 million, a barely believable fall of 43 per cent. Its vibrancy as a society is under threat due to lack of young people.

Japan is not much better. It has a shrinking workforce and rapidly ageing population. These factors, combined with bureaucratic government, have conspired to ensure that Japan has yet to recover fully from the crash of 1991. The position of China is more complex: it has no shortage of young and ambitious citizens at the moment, but the one-child policy imposed by the Communist Party has skewed the country's demographic profile. In a generation or so, China may find itself short of young people. It is in a race to grow rich before it grows old.

The extra million Americans will not all spring from the wombs of American mothers. The US will have to attract the brightest and most entrepreneurial young people from around the world, as will other greying states, provoking ever sharper competition to suck in new blood. "No western-derived country produces enough children of European descent to prevent them from becoming granny nation-states by 2050," Mr Kotkin has written. "In the next decades the fate of western countries may well depend on their ability to make social and economic room for people whose origins lay outside Europe."

Canada and Australia are already following this path, with strong repercussions. The Chinese government is trying to reverse the flow and entice students educated in Australia to return home. The influx of Indian students to Australia has led to a spate of racially-motivated attacks which has poisoned relations with the Indian government. In New Zealand - a country of 4.3 million - the anti-immigration New Zealand First party has said the country is in danger of becoming an "Asian colony".

For its part, the UAE is not an ageing country, but the greying European nations' rush to attract new blood cannot fail to affect it. It needs to attract the brightest and most daring if it is to succeed in its goal of being an educational, commercial and hi-tech hub. By all accounts the competition for these people is going to become more fierce. The UAE has many attractions for the upwardly mobile citizen of the world but one thing is lacking: a Chinese couple who make their home in Melbourne, San Francisco or Vancouver know that they will have more space to breathe than in overcrowded China, and will be free of the one-child policy and thus can have as large a family as they can afford. They will also be able to make a home for their children who can stay for generations, should their homeland - China or one of the many countries with large Chinese diasporas - become unstable.

The UAE attracts great talent that it now must consider how to keep. It has a couple things going for it that few other countries do: a stable government and a tolerant Islamic culture, important for people from the Middle East who fear their children will acquire the habits of teenage sex and public drunkenness that can be the norm in the West. America has also become somewhat less attractive to Muslim immigrants as a result of the reaction to the attacks of September 11. But most American Muslims still seem to be comfortably middle class.

With the availability of good jobs in most Arab countries lagging behind the ambitions of its ever more numerous graduates, there will be no shortage of people who want to come and work in the UAE. But the Government will have to bear in mind that the global competition for the best graduates will inevitably rise in the coming years . A talented Egyptian graduate may have a choice between working in California or the UAE.