India's life expectancy is projected to increase from the current 64.7 years to 75.6 years by the middle of the century. And that is close to the current US figure of 77.5 years.
As per the '2006 World Population Prospects,' a report of the population division of the UN Department of Economic and Social Affairs, the number of Indians over 65 years of age will almost quadruple from 6.4 crore in 2005 to 23.9 crore.
The number of those aged 60 and above will increase from 8.4 crore (7.5% of the population in 2005) to 33.5 crore (20.2%) in the next 43 years.
But there is also a note of concern in the report. When people live longer and birth rates decline, it means the ageing population will also go up.
By 2050, the number of Indians aged above 80 will increase more than six times from the current number of 78 lakh to nearly 5.14 crore.
Inevitably the population of those aged between 15 and 24 years of age will decrease from 21.8 crore (19.3%) to 21 crore (12.7%).
The study also warns that India's fertility rate in the age group of 25-29 years will dip from 160 to 107 while that in the age group of 30-34 years of age will fall from 81.9 to 61 by 2050.
Despite the declining fertility, India's population is expected to increase from 1.13 billion to 1.65 billion, making it the most populous nation on earth by 2050.