According to UN calculations presented in May today, October 31 2011, the world population reaches 7 billion people. If you would have to make a bet where, India is your best choice.

Zooming in to find the world’s 7 billionth human inhabitant. According to UN calculations he or she will be born somewhere on our planet – today. (Visit Infographics Page for full resolution image.)

With over 350,000 newborns sharing the same birthday there is of course no way to be sure. In India today an estimated 75,000 people will be born, quite a lot more than the numbers two and three, China (46,000) and Nigeria (17,000). [It is by the way why India will topple China in 10 years from now.]

If really you want to pin the tail of the donkey, next best shot would be Mumbai, as it is India’s largest city. You could then end up in one of the most densely populated neighbourhoods, like Dharavi Slum, world famous since Slumdog Millionaire.

A boy or a girl?

But perhaps it would be wise to spread your chances and also take a look at the Ganges Basin, currently the most important driver of Indian population growth.

That would diminish our chance of celebrating the birth of a girl. In the Indian state of Utar Pradesh for instance only 889 girls are being born to every 1000 boys. This is mainly due to sex-selective abortion says campaign group Plan International, which today holds a rally in India to challenge the practice.

Meanwhile in New York Ban Ki-moon will address the UN, to mark the 7 billion milestone. He will focus attention on challenges and problems arising from continued growth of the world population. It is only 12 years since the world population reached 6 billion.

Population projections, UN’s medium variant

And according to the medium projections of the World Population Prospects’ 2010 Revision we will only have to wait until 2025 to greet 8 billion. That would mean the world population would have doubled in just over 50 years time.

A Harvard study from a few months ago concludes up to 2050 97 percent of population growth will come from less developed regions. Most notable is Africa, where again according to medium UN prediction the total population will grow by 2.5 billion extra people over the course of this century. In the meantime many European nations will have declining populations. Today countries like Nigeria, Pakistan and Indonesia already have more inhabitants than Russia. By the end of the century even some small African nations, like Uganda and Malawi, would have larger populations than the world’s biggest country.

There is more agreement than there is policy – some versus none

To get back to today’s news: not everyone agrees on the calculations. It’s apparently more difficult to keep count than one would imagine. The US Census Bureau for instance thinks we’ll have to wait till March 30 2012 to great the 7 billionth human.

It is of course even harder to predict future developments – especially since these would depend on economic development, politics and policies and the possibility of cultural changes. But it is perhaps wise to assume some resilience on that last front, as so far the graphs have always needed upward adjustment.

That often assumed link between birth rates and poverty seems somewhat challenged by the fact that an average Russian woman gives birth to just 1.4 children, whereas in rich Saudi Arabia that number is still higher than 3.

Niger tops all other countries with 7.2 children per average woman – in Afghanistan that’s 6.6.

© Rolf Schuttenhelm | www.bitsofscience.org