In 2010, an estimated 524 million people were aged 65 or older—8 percent of the world's population. By 2050, this number is expected to nearly triple to about 1.5 billion, representing 16 percent of the word's population. Although more developed countries have the oldest population profiles, the vast majority of older people—and the most rapidly aging populations—are in less developed countries. Between 2010 and 2050, the number of older people in less developed countries is projected to increase more than 250 percent, compared with a 71 percent increase in developed countries.
This remarkable phenomenon is being driven by declines in fertility and improvements in longevity. With fewer children entering the population and people living longer, older people are making up an increasing share of the total population. In more developed countries, fertility fell below the replacement rate of two live births per woman by the 1970s, down from nearly three children per woman around 1950. Even more crucial for population aging, fertility fell with surprising speed in many less developed countries from an average of six children in 1950 to an average of two or three children in 2005. In 2006, fertility was at or below the two-child replacement level in 44 less developed countries.
In some countries, the sheer number of people entering older ages will challenge national infrastructures, particularly health systems.
This numeric surge in older people is dramatically illustrated in the world's two most populous countries: China and India ( Figure 2.2 ). China's older population—those over age 65—will likely swell to 330 million by 2050 from 110 million in 2011. India's population of 60 million in 2011 is projected to exceed 227 million in 2050, an increase of nearly 280 percent. By the middle of this century, there could be 100 million Chinese over the age of 80. This is an amazing achievement considering that there were fewer than 14 million people this age on the entire planet just a century ago.
This chapter includes text excerpted from “Global Health and Aging,” National Institute on Aging (NIA), National Institutes of Health (NIH), October 2011. Reviewed September 2017.