The world baby boom is finished.
By 2025, for the first time in history, the old will outnumber the young worldwide.
Good or bad, said William Kerrigan, UN secretary-general for the World Assembly on Aging (on July 26), ''There will be more than a billion people over 60 - and for the first time in history they will outnumber the young.''
What happens on a planet where most of the people aren't ''young'' anymore? There will be economic and other changes, but for the moment UN demographers recoil from giving an answer; they merely observe.
Representatives of 120 countries gathered to consider the problem of world aging at Vienna are absorbed in the statistical drama. Birthrates are falling, life expectancy rising; it is throwing vital statistics out of whack.
''Only in the past few months,'' Mr. Kerrigan explains, ''have UN demographic experts discovered the extent of the aging population explosion predicted for early next century.'' These are the first worldwide projections formally taken beyond 2000. The ''over-60s of 2025,'' as the new population is called, are today's 17-year-olds - and their numbers are huge.
The effect of population aging is argued as a triumph of development in some circles, but others call it a brake on progress.
''If there are proportionately fewer persons of working age,'' Mr. Kerrigan notes, ''their productivity must increase before the standard of living of the whole population can improve.'' An alternative, he says, is for older people to remain economically active - and that means more flexible retirement policies.
How does it affect the United States? Some workers are already feeling the pinch: ''The ratio of workers to pensioners has slid from 16 to 1 in 1950 to 3.2 to 1 today. By 2025 it will be 2 to 1.'' This is a big jump in a short time it is noted here, in what demographers call ''the dependency ratio.'' The prospect is that it will spread over the world and is now affecting the developing countries.
Industrialized nations cut birthrates some generations back. Now its the developing countries. Their population today is young - up to 50 percent under 25. The new projections argue that by 2025, nearly three quarters of the over-60 s will live in the third world. Countries like Brazil, Bangladesh, Mexico, and Nigeria will each see the number of over-60s increase by up to 15 times that of 1950. What happens then? Will it be a more calm, sedate, reflective world?
''And so the centuries-old population pyramid will begin to turn upside down; old will outnumber the young in all developing countries,'' says Kerrigan.