Every one of the roughly 50 trillion cells in your body contains a ticking biological clock counting down your mortality. We can’t yet read the clock’s face to reckon your expiration date, but some scientists now believe they have deciphered at least part of the message and can predict about how long people with the clock’s hands set like yours might live. You might even be able to hit the snooze button and improve the odds of a longer life.
These cellular clocks are called telomeres, tiny genetic structures found on the ends of chromosomes, and they are often compared to the protective aglets on shoelaces. Every time a cell divides and reproduces, the telomeres fray and get a little shorter. When telomeres become very short, cells either shut down or die.
Some scientists say their research shows that, in practice, telomeres respond to every beer drunk, cigarette smoked, vegetable chomped, and marathon run, recording them for posterity in every cell in the human body. They claim that peeking at this hidden data stream using simple medical tests can reveal one’s true biological age and even life expectancy. To be fair, other researchers rate the results no better at predicting mortality than the length of the crease between one’s thumb and one’s wrist.