Illustration: Michael Arnold

A sleeping giant is neither a threat nor a promise. In repose, eyes closed, it gives no indication of what it will do when it awakens—whether it will be the kind of giant that gently cups its hands around the helpless or pounds them down in fury.

In this series, we consider the sleeping giants that lurk in population change. From now to the year 2100, the number of people in the world is expected to grow much faster than ever before—from more than seven billion today to 10.5 billion. In the context of globalization and an expected surge in job-driven migration, that kind of growth could lead to both a rise in creative innovation and the threat of social unrest, as differing cultures converge in ways and with consequences yet unknown.

Explosive population growth and the effects of increasing ethnic, national, religious, and cultural diversity: Those are our sleeping giants. Based on interviews with experts, the latest research, and the best available statistical projections, this series constitutes a provisional report on what the expected shifts in global demographics may mean for the U.S. and the world.

Among the most pressing questions: How will the world deal with a population that is increasingly lopsided, with too few workers in job-rich, advanced economies and too many in the job-poor developing world? Which societies will gain and lose as populations move and otherwise adjust for that imbalance? What tensions can be expected when economic pressures for migration draw differing cultures together? And how might such tensions be resolved?

How, in short, do we ensure that our sleeping giants wake up on the right side of the bed?

Developed vs. Developing World: The Great Divergence

Although the global population is expected to keep growing until the end of this century, that growth is predicted to be extremely uneven. As explored in the article titled “Birth, Death, and Working Life: A Critical Balance” the populations of Africa and parts of Asia are growing larger and younger, while the populations of Japan, Russia, and nearly all of Europe are shrinking and aging. “The Continental Divide Between Workers and Jobs” considers potential solutions for that demographic dichotomy.

Growing populations of young people in nations in Africa and Asia will encourage migration toward jobs, which is expected to increase the number of the world’s megacities—urban areas with more than ten million residents. There are only 28 such cities today, but the prediction is that by 2030, there will be 13 more. The U.N. predicts that virtually all of that urban growth will take place in the developing world, a geo-demographic trend explored in “Rise of the Megacities: Is China Ahead of the Curve?.”

The great unknown is immigration. No one disputes the fact that populations will be shifting across national, regional, and continental borders, but there is a wide range of opinion about the scale and effects of that movement. A key variable in how well or badly a society deals with immigration, as Natalia Banulescu-Bogdan of the Migration Policy Institute explains in “The Immigration Fix,” is how fast the change is allowed to take place, an insight that implies useful strategies for maintaining social cohesion during such a time.

The Diversity Dividend

“Diversity has some costs and some benefits,” says Oded Galor, a professor of economics at Brown University, who has studied how both civil strife and economic abundance result from diversity. His research suggests that as societies become more diverse, they become more creative and more adaptive to technological innovation.

This may not have been much of a benefit in the distant past, he notes, when agricultural output was the primary indicator of a nation’s success and when maintaining an isolated, homogeneous society was the best way to safeguard the stability of the economic unit.

But what drives economic development today, he says, is not homogeneity and stasis but diversity and innovation. Galor found that as a society’s diversity gradually increases, the number of patents and scientific articles it produces tends to increase as well. “A new world that is much more demanding technologically has moved us into a position where diversity is highly rewarded in the marketplace,” he says. “Societies that are more diverse are performing much better.”

Not surprisingly, Galor’s research also found that the more heterogeneous a community is, the more likely it may be to suffer from civil strife. “We are basically genetically programmed to trust only people who are very similar to us,” he explains. Once upon a time, that was adaptive: “Otherwise, we wouldn’t have survived.” But to reap the benefits of diversity for the creativity and general health of a society, Galor says, the society must reconcile internal differences and embrace the people on its margins.

“Not all diversity that is present in society will necessarily be exploited,” says Galor. “If some parts of the society are not an integral part of its productivity, that is a problem.”

In this analysis, Africa and the Middle East are too diverse, ethnically isolated countries like Bolivia are not diverse enough—and the U.S., thanks in part to its historic acceptance of immigration, is close to a golden mean.

U.S. Demographics and the Economics of Empathy

Evidence provided in “LGBT: Acronym for a Changing Nation” suggests that the U.S. may well remain in that demographic sweet spot. More than 90 percent of respondents to a poll of the American lesbian, gay, bisexual, and transgender community claimed to feel greater acceptance by the general U.S. population than they did 20 years ago, which suggests a change that is both dramatic and incontestable: Very few poll results show 90 percent agreement on anything.

The millennial generation, which this year surpassed the population of the baby boom, is also redefining public attitudes toward gender, defying its hold on their behavior and destiny. The article “Millennials and Gender: A Major Attitude Shift” addresses some of the consequences for U.S. households and the workplace.

Attitudes toward race and ethnicity in American society are up for redefinition as well. As discussed in “Minority: A Word Without Meaning?”, minority kids already outnumber the children of non-Hispanic whites in more than 100 U.S. cities, and by 2035, non- Hispanic whites will be outnumbered in all age groups. People are marrying across ethnic and racial boundaries as never before, a practice that was widely frowned on only 50 years ago. Boomers see this as a positive sign, while millennials tend to see it as just commonplace.

As the U.S. embraces these and other aspects of its diversity, effects on the American family have been profound. Changes explored in “The Many New Faces of the American Family” include the fact that a record number of people—one in five adults—have never married; that more kids than ever have two dads or two moms; that 44 percent of all American children have step-siblings; and that less than half of them live in a “traditional” family, defined as one in which the parents are a heterosexual man and woman in their first marriage.

Polls suggest that Americans are evenly split on how they feel about such departures from convention, but according to Patrick Gerland, chief of the Mortality Section of the U.N. Population Division, “diversity has helped the U.S. stay more stable demographically over time.” Continuing its embrace of racial and ethnic differences, he says, may be the nation’s best hope for staying in the demographic Goldilocks zone.

In November, President Barack Obama established a new White House task force with the goal of “creating welcoming communities and fully integrating immigrants and refugees.” The group is soliciting ideas from experts and community leaders around the country and is building on the U.S.’s long experience with immigration. That history has hardly been smooth, but the nation that inspired the original term and vision for “the melting pot” promises to be among the world’s best models for adaptation to the new demographic order.