Demographics are the viruses of the human race. They are far from obvious, but they quietly replicate and assert their version of a new reality as inexorably as the passage of time.

What are seen as realities today are forgotten conceits tomorrow, after demography has unfolded. India rockets along its economic arc, becoming a global business giant and multilateral political player. Yet, at home, some 300 million people-most of them young, low caste, excluded, and angry-await their turn at the wheel. The recent Uttar Pradesh election result is just the first of many. India's demographics cannot be denied.

Iran's mullahs and cavorting prime minister cock a merry snook at the United States and its ridiculously inept administration. They are nurtured in the petridish of Washington's ire and cloak themselves and their words in Islam's cadences, flicking their eyes towards god's realms at every opportunity. But their fellow citizens are young, unemployed, and fed up with empty rhetoric and corruption. Iran will change beyond all recognition soon.

Western Europe lurches along, taking lengthy vacations to escape the angst of change in post-World War II realities. France atrophies but dines well even as its self-conceived civilisation becomes ever more irrelevant. Germany deludes itself that German genius will overcome all obstacles. Only Britain shows the slightest awareness of the coming assertion of demographics.

Sometime this century, Islam will become the most important faith in a continent that has long regarded itself rather militantly as Christian, and that has a history of war with Muslim civilisation. This change will be brought about by immigration and family dynamics, not war or policy. What's alarming is not that change is coming, but that Europe's leadership is wilfully blind to this prospect. Even the simplest step, admitting Turkey to that Christian club called the European Union, has them reaching for crucifixes and shields and talking like medieval popes.

In the United States, Spanish speakers are already the largest non-white minority and Asians are the most economically successful. Poor whites and African Americans aren't invited to the party. What do politicians do? They pretend they can build walls and enforce official language policies to reverse the tide of history. The real threat to American prosperity is not foreign waves but neglected backwaters within-communities and people mired in poverty and exclusion, left alone with their anger.

What about demography in Nepal? This too is a young country, where most people beyond a narrow ethnic and religious definition are left out of power and prosperity. Count on that youthful dynamism forcing open the doors to the feast and stealing dishes from the banquet or privilege. It's happening already. Count as well on the disappearance of national tropes that seem so relevant now-anthems, costumes, religious practice, and political symbols from Marx to the Shah dynasty-to be largely forgotten in a decade or two.

Human history moves at a stately pace, through generations, fuelled by demographics, new critical masses in the making, and the cumulative aspirations of the young, the excluded, the newly arrived, the ambitious.

If I had two words of advice for anyone in power anywhere in the world right now they would be: stand aside.