Health Checkup: How to Live 100 Years

A baby born in the U.S. today can realistically look forward to living to 100, scientists say, despite official life expectancies in the developed world in the high 70s to low 80s.

Confused? It's all in the language. The life-expectancy stat that's so commonly used is not, in fact, meant to reflect our expectations for the future. We can't know what medical breakthrough may come along to extend our lives or what plague may shorten them. Life-expectancy figures instead describe how long we'd live, hypothetically, if today's death rates never changed.

But Danish scientist Kaare Christensen and his colleagues have calculated a different kind of projection, one that assumes longevity improvements will continue at their current pace. In that model, more than half the children in the developed world will be around for their 100th birthday. Now may be a good time to invest in candles.

See portraits of centenarians.

Special Report: How to Live 100 Years.