For years, scientists have viewed extreme longevity as something largely determined by genetics. But research following tens of thousands of people suggests that the path to living exceptionally long may also be reflected in ordinary blood tests. A long-term Swedish study tracked more than 44,000 people for decades, with just over 1,200 eventually reaching 100. Researchers found that the future centenarians often shared something surprisingly simple: their biological markers remained relatively stable throughout life. Rather than extreme numbers, balance appeared to be the recurring pattern.

Markers involving glucose, kidney function, iron, cholesterol, and uric acid offered important clues. Strong kidney and liver function, along with lower levels of chronic inflammation, were commonly associated with exceptional longevity. Some results were unexpected, including findings that slightly higher cholesterol could be associated with survival into very old age. Genetics still influence aging, but lifestyle can shape how those genetic tendencies play out. Regular movement, sufficient sleep, stable blood sugar, and moderation may therefore matter far more than chasing perfection.