What worries me is the ongoing "greying" of the world population, which is uneven globally but widespread. It is not "on the radar" (except for occasional gee-whiz news stories and narrow discussions about particular problems for this or that trade). But it should be—both the coming vast increase in the number of elderly people and the general rise in average age, as middle-aged and older people come to represent a greater share of humanity.
For example, out of the 9 billion people expected when the Earth's population peaks in 2050, the World Health Organization expects 2 billion—more than one person in five—to suffer from dementia. Is any society ready for this? Is any really talking about how to be ready?
At the coming mid-century, in rich nations nearly one person in three will be more than 60 years old. But this upheaval won't be confined to developed world. The Chinese population's median age is now almost 35; by 2050 it will be 49. India's population of people aged 60-80 will be 326 percent larger in 2050 than it is now. Elderly people, now 7 percent of Brazil's population, will make up nearly a quarter of that country in 2050. Yes, a swath of poor nations in Africa and Asia will soon go through classic population explosions, and will teem with young people. But they will be exceptions to a global trend. "Before 2000, young people always outnumbered old people," Rockefeller University's Joel E. Cohen wrote a few years ago. "From 2000 forward, old people will outnumber young people."
Awareness of this demographic shift is partial and piecemeal. Public health specialists discuss the expected huge increases in cases of "grey" diseases—chronic non-communicable ailments like heart and lung problems, stroke, diabetes and kidney failure. Economists talk about the disruptions that follow when working-age people are too few to support many retirees. Financial types bemoan the many millions of people who could not or would not lay away money and now face decades with no obvious way to take in the income they'll need. Governments in India and China have introduced laws to prop up family values in the wake of stories of old people abandoned by their adult children. Within each discipline and profession there's some discussion of this vast disruption but almost no one, to my knowledge, is discussing the underlying cause or trying to map out the consequences and relate them to each other.
The greatest worry about this shift turns on the social safety net. Most developed and developing nations promise at least some security and medical care for the old. That promise depends on the pyramid structure of a 20th-century society, in which active working-age people outnumber the retirees. It's hard to see how those social-security guarantees can stay in place when there are fewer young workers for more and more older dependents. China, for example, now has about six workers for each retired person. On current trends that ratio will be two workers per retiree by 2050.
That's a prescription for labor shortages, falling production, and political uproar as promised pensions and health-care for the elderly become impossible to pay for. And this is one reason why China is expected to relax the famous "one-child" policy that now applies the majority of its people—and the reason why more and more nations are trying to increase their fertility rates. How else do you forestall this kind of crisis? Well, you could raise the retirement age, so workers support retirees for longer. But that's not acceptable, for a number of practical and political reasons. One of which is that in a number of countries the retirement age would have go into the late 70s for this to work.
Politically, I worry about the consequences of a shift in power and influence away from younger people to the middle-aged and the old. In democracy there is power in numbers, and if the numbers give power to older people, then I fear their concerns (for keeping what they have, for preserving the past as they imagine it, for avoiding the untried and the unfamiliar) will start to overwhelm those of younger people. This has never happened before, so we can't know exactly what its consequences are. But I doubt they're good.
I think we can expect to see some frank and ugly intergenerational conflict. Even the United States, which faces less greying than other rich nations due to its openness to immigration, is in the beginnings of a policy debate about pensions and medical care that pits the interests of older workers (secure and predictable pensions and medical care) against those of younger people (education, future infrastructure, opportunity).
In countries where greying is happening really fast (Spain, Italy, Japan), one consequence might be an upsurge in xenophobic nationalism, for two reasons. First, there's good evidence that openness to change and new experiences declines with age (Robert Sapolsky actually devised some tests for this, back in the 90s, and concluded that the window for being willing to try new music closed, for his American subjects anyway, at 35, while openness to food ended around 39). People who could like a crude nationalist message—"let's get back to the way things were in the old days, before things went bad"—will be a bigger proportion of voters.
Second, because of the economic trouble I've already mentioned, nations will be looking for ways to boost their active workforces, to support all those retirees. And here the options are (a) boost the birthrate or (b) open doors to immigrants from all those poor youthful nations in Africa and Asia or (c) make a lot of robots (as they seem to trying to do in Japan. Options (a) and (b) are obvious triggers of xenophobic rhetoric ("young women must do their duty and make more of us!" and "we have too many of these damn foreigners now!").
Finally, on the cultural front I worry about too much deference being given to the fears of people my age (54) and older. In the past 20 years, it has become intellectually respectable to talk about immortality as a realistic medical goal. I think that is an early symptom of a greying population. Here's another: When we speak of medical care, it's often taken as a given that life must be preserved and prolonged. Ray Kurzweil has said that whenever he asks a 100-year-old if she wants to reach 101, the answer is yes. Has he asked the 100-year-old's children, neighbors or employees? They might give a different answer, but in a greying world, the notion of natural limits and a fair share of life becomes taboo.
Richard Posner described the pre-greying dispensation this way: "In the olden days, people broke their hips and died, which was great; now they fix them." Posner grew up with the simple and once-commonsensical notion that you have your time on Earth and then you get out of the way. Because other, younger people are here, and they need to take your place. They'll need money for something other than their parents' practical nurses, they'll need the jobs older people won't retire from, they'll need the bandwidth that we old people will fill with talk of tummy tucks and IVF and Viagra. And they will need to have some decades out of the shadow of their parents. Once, people who were dutiful if not lovingly devoted to their elders could count on liberation. (I think of Virginia Woolf, whose father died at 71, writing 25 years later: "He would have been 96, 96 yes, today; but mercifully was not. His life would have ended mine. What would have happened? No writing, no books—inconceivable.") I fear it is becoming acceptable, due to the demographic shift, to tell younger generations that their day might never, should never, come.
Perhaps, though, I should be more positive, and less like a typical 54-year-old, extolling the way things were in my youth. No doubt the greyer world will have its advantages. (Older people, for example, consume less power and fewer products per capita. In 2010 Brian C. O'Neill and his colleagues analyzed that effect and concluded that global greying might supply as much as 29 percent of the reductions in carbon-dioxide emissions needed to avert a climate catastrophe this century.) Whatever one's attitude toward greying, though, it is indisputably happening. It deserves much more attention.