With the advent of commercial telomere length measurement services, there's been a lot of unscientific hype in the media of late about tests that will show how long you're going to live. Some more sensible commentary here from FuturePundit: "the test can not precisely predict your year of death. Too many factors (accidents, suicide, and murder aside) influence your date of death. Take cancer for example. There's a lot of randomness involved in determining when we'll get cancer. The accumulation of damage in cells can make them turn cancerous. But just when the right set of genetic mutations or other cancer-promoting damage will occur in some cell in one's body is as hard to predict as when someone will win a lottery. Many things have to line up just right all in the same cell to make it cancerous. Every day is basically another throw of the dice. Will a bunch of mutations all line up to send a cell of yours into dangerous mad replication and growth? Better longevity tests seem useful for retirement planning. Should you save enough money to support yourself to age 95? Or expect to die by your late 60s? A telomere test could help you decide difficult questions about your savings rate and career choices. Do you need to work past age 70 to save enough money to avoid going broke in your 80s and avoid poverty in your 90s? A better sense of the odds would help. Of course, before we hit our biological shelf life expiration date some of us just might live long enough to still be around when rejuvenation therapies become available. Injections of youthful stem cells with long telomeres could replace older tired cells with short telomeres. This would be great for the immune system, for example, because a youthful immune system will do a better job of fighting cancer. Also, youthful cells for the cardiovascular system could cut the risk of heart disease, stroke, and other killers." The high level point being that unless you are old already the future of your life span has less to do with your telomeres and more do to with progress in medical science.