Quietly, without much notice, the world's population crept past the 7 billion mark on Oct. 31, according to the United Nations. The majority of people live on one continent, Asia, with two countries, China and India, accounting for almost 37 percent of the total.

What is striking is that while it took thousands of years for the population to reach the 1 billion mark — about 1830 — it took only 100 more years for it to hit 2 billion and, in the last eight decades, an additional 5 billion people were added.

In the past, there was a view that too large a population was a drag on economic growth. That certainly was behind China's one-child policy, introduced by Deng Xiaoping after the death of Chairman Mao Zedong. Ironically, now, the world's two most populous countries are also its most rapidly developing economies.