Living to 1000? A new book on ageing says that in the future, people will routinely live to 150 and that the first people to reach 1000 years of age may have already been born. — agediscrimination.info

Another promising new technology is organ printing, which is exactly what it sounds like: Cells, rather than ink, are put into a sophisticated 3-D printer and then printed onto a biodegradable material. The machine prints “pages” of cells on top of each other to make a three-dimensional shape. In December 2010, a company called Organovo announced that it had successfully printed human blood vessels—an important feature of all organs.

At the McGowan Institute for Regenerative Medicine at the University of Pittsburgh, Stephen Badylak is working with “extracellular matrix”—the material that gives structure to tissue—from pig bladders. Dr. Badylak has used ECM to grow back the tips of patients’ fingers that have been accidentally snipped off, and his colleagues have used it to cure early-stage esophageal cancer by removing the cancerous cells and replacing them with ECM. Scientists don’t yet understand why the substance promotes new tissue growth, and ECM can’t yet grow back entire limbs, but the results so far are impressive.

Assuming that the necessary technology eventually arrives, the big question is: What will life look like when we live to over 100?

One of the most important areas of potential change is family and relationships. With an average life expectancy of 150 years, it’s possible that we might see age differences of as much as 80 or 90 years between spouses and partners. But the historical evidence suggests that such disparities in age probably won’t be common.

Research by Norway’s government statistics bureau shows that between 1906 and 2002, life expectancy rose from around 57 years to around 79 years in that country. But the average age difference in relationships remained at around 3.5 years (men being slightly older).

One reason for the rarity of relationships with large age gaps is that modern societies tend to look down on them. Will the number of men marrying much younger women continue to grow as people live longer and such relationships become less stigmatized?

Research done at Stanford, the University of California, Santa Barbara, and the University of Wisconsin suggests that older men seek younger partners primarily to continue having children. If that is the case, such men won’t need to find younger partners once it is easier for older women to have their own biological children using new fertility technologies.

And in the future, older women (and men) will likely look less “aged” because they will remain healthy for much longer. Remarriage for beauty or youth will lose some of its distinguishing force.

More time to live also raises the possibility of more divorces and remarriages—the seven-year itch turned into the 70-year itch. Today, some people get married two or even three times, but as people live longer, these numbers could increase, perhaps exceeding Liz Taylor proportions for at least a small slice of the population. But greater longevity might also lead to a higher incidence of serial monogamy, regardless of whether it leads to marriage, perhaps interspersed with periods of living alone.

As researchers further refine reproductive technology like egg freezing and ovary transplants, the ranks of older parents, currently on the rise, are bound to increase even more. This raises the prospect of families in which siblings are born many decades apart, perhaps 50 years or more. How would such age gaps between children change family dynamics?

We know that siblings of the same age cohort have more meaningful and longer-lasting relationships than those separated by more years, but it is difficult to predict how the relationship between siblings born decades apart would function. It probably would be akin to that of a child and an aunt or uncle, or even a child and a grandparent.

Living longer would also mean both making and spending money longer. What would an economy look like in which work lives extended into a second century of potential productivity?

Most of us already don’t expect to retire at 65. The Social Security system cannot afford it even now, and in the future, going out to pasture at 65 will mean decades of boredom. People who live to 150 will use their additional years for second and third careers, and we are likely to see a greater movement toward part-time and flex-time work.

It has long been clear that wealth creates health. We now know that health also begets wealth. In a paper titled “The Health and Wealth of Nations,” Harvard economist David Bloom and Queen’s University economist David Canning explain that, based on the available research, if there are “two countries that are identical in all respects, except that one has a five-year advantage in life expectancy,” then the “real income per capita in the healthier country will grow 0.3–0.5% per year faster than in its less healthy counterpart.”

Although these percentages might look small, they are actually quite significant, especially when we consider that between 1965 and 1990 countries experienced an average per capita income growth of 2% per year.

Those numbers are based on only a five-year longevity advantage. What if a country had a 10-, 20-, or 30-year advantage? The growth might not continue to rise in linear fashion, but if the general rule holds—a jump in life expectancy causes an increase in economic growth per capita—then having a longer-lived population would generate enormous differences in economic prosperity.

In a 2006 study, the University of Chicago economists Kevin Murphy and Robert Topel painstakingly calculated that for Americans, “gains in life expectancy over the century were worth over $1.2 million per person to the current population.” They also found that “from 1970 to 2000, gains in life expectancy added about $3.2 trillion per year to national wealth.”

The world’s advanced societies are finally in a position to launch a true offensive against the seemingly irresistible terms imposed on our lives by disease and death. That’s good news for us as individuals and for humanity as a whole. A longer span of healthy years will lead to greater wealth and prospects for happiness.

But realizing the full potential of the longevity revolution will not be easy. We will need to tackle important and legitimate questions about the effects of greater health spans on population growth, resource availability and the environment. The decisions that we make in this regard will matter far more than the mere fact of greater numbers.

The very idea of radically greater longevity has its critics, on the right and the left. Leon Kass, who served as chairman of the President’s Council on Bioethics under George W. Bush, sees the scientific effort to extend life as an instance of our hubris, an assault on human nature itself.

The environmental writer Bill McKibben, for his part, strongly opposes what he calls “techno-longevity,” arguing that “like everything before us, we will rot our way back into the woof and warp of the planet.”

I’m unconvinced. Arguments against life extension are often simply an appeal to the status quo. If humans were to live longer, we are told, the world, in some way, would not be right: It would no longer be noble, beautiful or exciting.

But what is noble, beautiful and exciting about deterioration and decline? What is morally suspect about ameliorating human suffering?

The answer is nothing. Everything that we have, socially and as individuals, is based on the richness of life. There can be no more basic obligation than to help ourselves and future generations to enjoy longer, healthier spans on the Earth that we share.

Adapted by Wall Street Journal from “100 Plus: How the Coming Age of Longevity Will Change Everything, From Careers and Relationships to Family and Faith” by Sonia Arrison. Available from Basic Books. Copyright © 2011.