By Chris Adams

America – and the world – is aging. Many of the reasons why are known.

But many others remain a mystery.

In a session with National Press Foundation fellows, Dr. Luigi Ferrucci, scientific director at the National Institute on Aging, laid out the demographic trends that are transforming the world from a young one to an old one.

The institute, which is part of the National Institutes of Health, studies diseases such as Alzheimer’s and Parkinson’s; demographic trends; and overall life expectancy.

Ferrucci described the expansion in the elderly population – and how it is expected to continue. In the United States, the over-65 population is projected to nearly double, from 48 million people to 88 million by the year 2050.

Global life expectancy is expanding at the same time, and is projected to increase by almost 8 years, from 68.6 years to 76.2 years by 2050. The ranks of the very old – those 80 or older – will triple during that time, to 447 million worldwide.

And that’s how the world is switching from young to old: The number of people worldwide who are 65 and older is about to surpass the number who are under 5.

“There were probably people living to 100 years in Roman times – but they were really, really rare,” Ferrucci said. “A larger part of the population is now able to survive to old age, and to survive in a decent, healthy condition.”

He talked about how bodies age, including how smell is often the first to go as people age; how muscle mass diminishes as well; and how the evidence of nutritional intake on longevity isn’t as strong as many people think. And he talked about “geroscience,” which is the convergence of two fields of study: the biology of disease and the biology of aging.

Finally, he left fellows with a perspective on how attitudes change.

Ferrucci shared a physician’s column from a Baltimore newspaper in 1950. That doctor’s advice? “Don’t over-exert – exercise after the age of forty won’t keep you young and may, if overdone, hasten old age. … Don’t play or work to the point of being ‘short of breath.’ ”

Finally, this doctor said, there’s “no indication that alcoholic beverages, or smoking, in moderation” have any effect on longevity.

That was convention wisdom at the time – and it’s all been discredited.