If you look at a long enough timeline, getting older is now an exercise in getting younger. According to new research from the Max Planck Institute for Human Development, in Berlin, the people who turn 75 this year will, on the whole, be more intelligent, physically fit, and happier than the people who turned 75 roughly two decades ago.

In 1980, aging research took a hard turn with the introduction of a new hypothesis, dubbed the compression of morbidity. It departed from the commonly held idea that as medical science extended people’s lives, diseases would extend with them. People who once spent four years living with Alzheimer’s, for example, might now suffer twice as long. But that notion left no room for innovation that could delay the onset of disease or improve current treatments. The compression of morbidity did, and in 1998, a 20-year study confirmed the theory held true.

Aging Both Ways

Aging used to mean guaranteed disease. In 1900, for instance, infections made up more than half of all deaths, particularly as people’s immune systems waned as they got older. But today’s populations are ravaged by heart disease and cancer, not to mention diseases specific to longevity, such as Alzheimer’s and other dementia.

These aren’t exactly preventable — Alzheimer’s is one of medical science’s largest question marks. But they do leave us with more control. Denis Gerstorf, developmental psychologist at Humboldt University, argues today’s older adults believe less in things like luck and fate than people did 20 years ago. “Differences seem to exist in what psychologists call control beliefs — whether people think that they are the ones who determine the things that happen in their own lives,” Gerstorf told Medical Daily. With more control, many opt to take the reins on their health.

Those are the results of Gerstorf’s latest study into aging, which he carried out with colleagues from Max Planck. Looking at two stages of the Berlin Aging Study, the first carried out between 1990 and 1993 and the second between 2013 and 2014, the team made some large-scale assessments of how old-age vitality has changed, along with some speculations as to why.

Overall, despite growing obesity concerns and a stagnant international smoking rate, people seem to be aging more gracefully. Past the advances that have kept people in better physical shape, cognitive tests showed 75-year-olds today were an average of 19.6 years “younger” relative to 75-year-olds in the early 1990s. That is, people tested at 75 today performed as well as a 55-year-old would have two decades ago.

“This is, by any means,” Gerstorf said, “a huge effect.”

Issues On The Table

Perhaps more important to future research is understanding what’s driving these changes. Education plays a big part, Gerstorf says, as a more informed society is likely to be a more intelligent society. A much larger factor is the general improvement of public health, which causes domino effects in other aspects of daily life. Healthier people prefer to be more socially and physically engaged, which keeps them biologically younger. Unlike those who sit at home and let their brains atrophy, people who maintain exuberance in old age are given a kind of compounding reward for it: They use their health to do other healthy activities.

Unfortunately, not all factors are within people’s control. Some are structural. A study from the University of Wisconsin recently found that not only do low levels of income shorten a person’s life expectancy; income inequality does it, too. The same effect crops up in places where pollution is heavy, where stress is higher, and, indeed, where income is lower overall. Susan McDaniel, sociologist and demographer at the University of Lethbridge, says these larger forces are only starting to become untangled, and what’s still left for future research is how these factors “get under the skin” to leave lifelong effects.

“We don’t understand those mechanisms,” McDaniel said, “and that is something that is really on the table.”