Time was, old people knew their place. Scepters were passed to sons and daughters, crowns placed on younger heads. The elderly would watch human follies from their rockers, grandchildren gamboling at their feet. Not any more. The elderly are no longer a sidelined sliver of society, but its mainstream. During the next two generations, the number of the world's people older than 60 will quadruple, rising from 606 million now to 2 billion in 2050. For the first time in human history, the elderly will outnumber children. More and more, it's not the children who are our future, it's the seniors. The graying of the globe is quite simply the "most significant population shift in history," says Ann Pawliczko of the United Nations Population Fund.

And growing old doesn't mean what it used to. Better medical care has increased the average global life expectancy by two decades--to 66--in as many generations. "One hundred is the new 60," cracks Marty Davis, of the American Association of Retired People. In the West, technology and wealth are empowering the aged. They are an increasingly vocal political lobby and muscular consumers. The portfolio of Senioragency, Europe's only ad agency aimed at the 50-plus market, used to consist of hearing aids and insurance. Now mainstream companies like Coca-Cola and Siemens are approaching the firm. "We're used to thinking of a 60-year-old who looks like "Whistler's Mother," but we should be thinking about someone who looks like Tina Turner," says Gloria Gutman, president of the International Association of Gerontology.

The elderly of the future may live longer, but the gap between the wealthy and poor seniors, and the fit and feeble ones, will be even more pronounced, says Eike Wenzel, an aging expert at Germany's Future Institute. In transitional economies, migration and urbanization are chipping away at traditional family structures--and with them, old people's status and support networks. In Africa HIV has transformed a generation of grandparents into de facto parents; they're the main group of caregivers for AIDS orphans. In Eastern Europe the breakdown of multigenerational families and communist welfare systems has created "a lost generation," says Polish former social-care employee Krzysztof Dopierala from Warsaw. In Russia the stress of post-communist economic flux has hit the older generation hard, leading to alcoholism and stress, particularly among men. Mokei-Gora, a farming hamlet 400 kilometers north of Moscow, is an all-woman village, its youngest resident 66. "We buried all the men," says 69-year-old Yekaterina Khokhlova.

The rapidly shifting demographics are forcing a radical rethinking of many facets of our lives. Two billion elderly will need new systems of care and support. The growing number of old people who want to live independently will need housing, streets and cityscapes that will accommodate their slower pace. Smart technology will have to plug nursing shortages; architects and social planners will have to start catering for populations with dementia and failing eyesight or hearing. In contrast to the youth-driven culture of the last half century, the elderly will set the agenda for how the late-21st century lives. Already societies have begun facing the pension crisis, the scariest specter haunting Western treasuries. But pensions aren't the half of it. For one thing, 80 percent of the world already can't afford to retire. Even in Western Europe and the United States, say experts, the very concept of retirement may soon be viewed as a historical aberration--a social curiosity from the era between World War II and the war on terror. And paying for the elderly is just a fraction of the massive upheaval underway. What's been dubbed "the silent revolution" is changing everything from politics to tax structures to the width of the world's doorways (for wheelchairs). It demands creative solutions to issues from steps on trains and buses to bottle caps too tight for arthritic hands to epidemics of depression. "Every sector of society needs to rethink the way we do business," says Edwin Walker, U.S. deputy assistant secretary for aging.

Visionaries are beginning to do just that. Hallmark, the American greeting-card company, offers an ever expanding range of birthday cards for the 100-plus crowd. It expects to sell nearly 90,000 of them by the end of the decade. In Mexico, Japan and a clutch of other countries, groups of seniors are following the American model by organizing into political lobbies. The new generation of oldies is rejecting the stock notion of nursing homes in favor of staying in their own houses, or clubbing together in small groups to create postmodern elder families. Designers are developing gadgets aimed at geriatrics, like wheelchairs that use the Global Positioning System and walkers with onboard computers to identify obstacles and clear pathways. Urban planners are starting to develop communities like Arabianranta, an elder-friendly quarter of Helsinki, Finland, where broadband links all 8,000 residents, and the sidewalks have no cracks to trip up old feet.

The "silver tsunami" is rising most ominously in Asia and Africa, which have the fastest-growing elderly populations. Singapore gives tax breaks to children who live with their aged parents; laws provide parents with the right to take their kids to court if they don't provide for them. Korean government employees caring for their parents get loans for houses and monthly stipends. In a pilot program in Shanghai, volunteers take care for the elderly in exchange for points, to be reclaimed in kind when they themselves grow old.

Everyone is trying to figure out how to look after this new generation of elderly, who will probably live long lives without ever going back to their extended family for care. Western countries are developing their own fresh approaches. The buzzword among European and American gerontologists is "aging in place," in which the elderly continue to live in their own homes rather than move to sterile, expensive institutions. The quest for independent living has generated new technologies, both low and high. "Ninety percent of the elderly can stay in their own homes with just small, inexpensive modifications," says Eckhardt Feddersen, a Berlin architect specializing in aging issues. Solutions as simple as stools in elevators and on staircase landings, or handles to help people navigate the bathroom and kitchen, can keep many old people out of nursing homes.

More complex devices are on the way. In Rome, elderly citizens living alone are issued telesoccorsos, warning devices that monitor basic functions like blood pressure and heart rate, with buttons to press in case of emergency. The German Fraunhofer Institute for Automation has developed the Care-o-bot, a robot that takes orders and delivers drinks, freeing up caregivers for more important chores. At the AgeLab at the Massachusetts Institute of Technology, inventors have created the Pill Pet, modeled on the Japanese Tamagotchi, a faddish toy in 1997. When patients forget to take their pills, the pet will frown, then sicken and die. The only revival technique: visiting the doctor or pharmacist to "reboot" the pet with pills--and get a lecture on the importance of taking them. Miss Daisy, a bright red Volkswagen, has a collision-avoidance system designed to help elderly drivers make left-hand turns more safely.

Seniors who can't live independently now have many options. In Britain and the United States, geriatric day hospitals merge adult day care, home care and health care, allowing seniors to get assistance and socialize by day, but return to their homes at night. Some German seniors are retooling the hippie tradition of communal apartments for their twilight years, living together and pooling their money to hire part-time help, get groceries delivered or order in doctors or nurses. For elders who need on-call nursing, there's a growing network in the United States, Europe, Japan and Australia of the Green House Project, offering elders round-the-clock care in homey settings. A trained nurse is always on call, and assistants maintain the cozy, pleasant household of about nine seniors. "It's like living in a college dorm without the blasting music at 3 in the morning," says its founder, American geriatrician, Dr. William Thomas. At a Green House in Tupelo, Mississippi, the long dining-room table is set with place mats and fresh-cut flowers, and the smell of baked goods wafts from the "hearth" room to the open kitchen. Elders and caregivers sit down to a family-style meal that can stretch on for hours. Residents take pride in doing things they hadn't been able to do for years in their former nursing homes. One resident actually cried when she was able to bake cornbread again, recalls project director Jude Rabig. "They really grab onto the fabric of life again."

That is crucial for a good old age, say gerontologists. China has a strong network of "elderly universities," run by the aged themselves. On a recent sunny day at the Beijing Dongcheng District Elder University, a packed class of seniors listened to a famous art professor--funkiness incarnate with his tinted glasses and wild mane of white hair--as he taught them to paint a branch of cherry blossoms. Across the courtyard, students sat on stools while their partners practiced massage. "It's paradise for old people," says 75-year-old He Jixian, a retired art teacher.

Still, paradise is the exception rather than the rule. Youth, not age, remains a far sexier target for policymakers and other professionals. Politicians with four-year terms aren't necessarily going to tackle aging policies that require decades of planning. The United Nations Secretariat has just three people working on the world's aging issues, compared with UNICEF's staff of 7,200. In results-driven professions like medicine, aging has the taint of failure, not success. "In old age, the outcome ultimately is death," explains Robert N. Butler, professor of geriatrics at the Mount Sinai School of Medicine in New York. "It's not as attractive to young physicians as heroic things, like trying to cure cancer." Of the 144 medical schools in the United States, only five have gerontology departments. In poor countries, the reaction to aging patients can be even blunter than benign neglect. Elderly Africans are frequently turned away from public-health clinics, says Monica Ferreira, director of the Cape Town-based Albertina and Walter Sisulu Institute of Aging in Africa. "Nurses tell them, 'You are old--what do you expect? We don't have medicine for you. Go home and die.'"

Among the world's biggest challenges is changing this youth-oriented mind-set. When Hurricane Ivan was poised to hit Jamaica last summer, the island stocked up on diapers and baby food, but not incontinence pads. In Africa, health workers and policymakers alike often refuse to acknowledge that HIV infects the elderly as well as the young. "People don't want to believe that the elderly are interested in the sexual act," says Tavengwa Nhongo, of HelpAge Africa. "But they are." Research in Uganda, for example, found that 20 percent of all over-50s who came for HIV testing were infected.

Even as the West tries to find ways of keeping the elderly out of nursing homes, the new middle classes in developing countries are resorting to them more and more. A decade ago nursing homes were unheard of in China and India, where filial loyalty was a cornerstone of traditional beliefs. During the past few years, private nursing homes have popped up in cities and boomtowns. In China they cost $200 a month, meaning only the wealthy can afford them; many younger Chinese see nursing homes as status symbols. Beijing has tried to stall what they see as the disintegration of traditional Confucian values by making it illegal for children to neglect aging parents. Neighborhood committees, once responsible for stamping out ills from prostitution to bourgeois behavior, now monitor families and have the right to file lawsuits against those that abandon their elders. "The developing world may well make the same mistakes that we made," explains Gutman. "Consumers somehow think that if it's medicalized, then it's good."

Not always. In India, there's a huge gap between the situation of the elderly in villages, where traditional family networks still exist, and in fast-growing cities, where modernization means they're breaking down. Kona Devi, a 72-year-old widow, lives in Kalyanpur village in West Bengal with her elder son's family. She counsels her daughters, who drop by frequently, looks after her son's house when he and his wife go to work and tells stories to doting grandchildren. "I feel loved and cared for," she says. "All my needs are fulfilled."

Devi may have bad arthritis and a measly monthly pension of about $7, but she's a far sight happier than retired bank executive Vijay Mohan. The 64-year-old used to live with his son's family in Mumbai. But soon he started feeling neglected, waiting endlessly for meals at night after his family returned from work. "Younger people today lead a very hectic life to stay ahead of the competition," he says "They have no time for elderly people at home." Mohan, like an increasing proportion of India's urban middle class, found himself having to think as an individual rather than a member of a family: "We have to learn how to make ourselves happy." He took himself to an old-age home in Pune, where he waits eagerly for the monthly visits from his son.

In former Soviet bloc countries, where the last 15 years have brought massive upheaval, the elderly are frequently at the sharp end of economic liberalization. Under communism, many families lived in multigenerational houses, with grandparents caring for the children. Increasingly, young people are traveling abroad to work, leaving the elderly to fend for themselves in countries that have yet to set up many residential care homes. Social workers in Prague, the city with the highest population of senior citizens in the world--29 percent of residents are over 60--report the elderly are frequently under pressure from children or private landlords to leave their flats, in order to free them up for quick sales or higher rents. Jan Lorman, founder of an elder-care project called Life 90 says pressure sometimes extends to physical abuse, and to sedating pensioners in order to intimidate them. Other countries in economic flux report a frightening rise in elder abuse. In South Africa the elderly are frequently attacked by their relatives for their money, reports HelpAge's Nhongo. "Nothing happens, as the victims do not want to see their flesh and blood suffer in jail."

Perhaps the most common thread uniting seniors from Biloxi to Beijing is the danger of isolation. Last August a European heat wave killed 7,000 Italians and 15,000 French--most of them old, many of them left behind by vacationing families. Many were abandoned in death, too: hundreds of corpses went unclaimed. Prague social workers say some city seniors haven't been out of their apartments in two decades.

But mass loneliness needn't be the world's newest misery. German university towns have thriving exchanges called Home for Help, where students in need of cheap digs move in with seniors looking for company and help with chores. Two years ago the village of Saint Apollinaire, near Dijon, created France's first intergenerational planned community. Half of its residents are young, low-income couples with babies or toddlers, the other half are seniors. To live there one must sign the Hello Neighbor Charter, a commitment to be an active member of the community. "We can't force people from different generations to interact, but we do everything in our power to make it easy," says cofounder Pierre Henri Daure. "Elderly retired schoolteacher seeks family willing to adopt grandfather," read an ad earlier this year in the Italian paper Corriere della Sera. "Will pay." Placed by Giorgio Angelozzi, a depressed widower, the ad worked. Angelozzi, 79, now lives in a village outside of Milan where he is nonno to two teenagers and their parents, paying 500 euros a month to cover his expenses. With solutions like Angelozzi's, the gray new world could be a brave new one.