Your Body Is Many Different Ages

By Debra Kelly on Thursday, August 28, 2014
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“I still think of myself as I was 25 years ago. Then I look in a mirror and see an old bastard and I realize it’s me.” —Dave Allen

In A Nutshell

How old are you? Whatever you answered, you’ll be glad to know that you’re not 100 percent correct. Researchers have now developed an algorithm that examines the amount of patterning and chemical buildup in DNA, allowing them to get a look at just how old the different tissues in our bodies actually are. For example, if you’re female, your breast tissue is about three years older than the rest of you.

The Whole Bushel

Our age is probably one of the first things we’re asked, along with our names and whether or not we’d like to pet the puppy. We’re taught to count our age first on our fingers, then in terms of when we can enlist, when we can drive or vote and, perhaps most importantly, when we can legally drink. Most of us are less proud of it as we get older, but it turns out that that number we’re taught to recite and the years we’ve been on this Earth have very, very little in common with the actual age of our body.

This isn’t one of those, “Fill in the answers and see how old you really are,” types of questions, either; those are based on the idea of the wear and tear we inflict on our bodies with our hobbies and habits. It turns out that the answer to how old we really are is a lot more complicated than that, and it actually has a lot of different answers—to processes that our body does naturally.

It turns out that different parts of our body age at vastly different rates; it’s something we might have been suspecting for a long time but science has now proven is true.

Researchers from the University at California have isolated a way to determine just how fast different parts of your body are aging. It involves looking at a person’s DNA, and isolating something called methylation patterns. Different types of tissues have different patterns, and these patterns become more and more “methylated” (that is, show a change in the amount of chemical groupings in them) as they age. This allows scientists to determine the actual age of a particular tissue.

Oddly enough, one of the fastest-aging tissues in the human body is female breast tissue. Samples of this tissue taken and viewed through the lens of this methylation pattering method—also called epigenetics—shows that breast tissues appear to be about three years older than the body’s actual age. It’s thought that this premature aging might be one reason that breast cancer is so prevalent, as cancer cells also show pretty drastic premature aging.

In those cases, cells are up to 36 years older than the rest of the body.

It’s not all doom and gloom, though, and researchers also found that there are some tissues that are younger than your numerical age. Heart cells, which are constantly replenished by the presence of stem cells, can be tested as several years younger than you proudly declare yourself to be on each birthday.

The method had been proven extremely accurate across a number of different tissues, such as tissues from the heart, liver, lungs, colon, and even the blood. (Blood cells have different life expectancies, with some lymph cells living for years.)

The discovery has some interesting potential applications, including accelerating the study of aging and age-related diseases. Scientists will be able to pinpoint if the problems a person is suffering in conjunction with aging are impacting the whole body, or only a certain element. It’s thought the method may even be able to predict different types of cancers by detecting cells in the body that are aging at an accelerated rate.

The scientists responsible for the discovery have released their algorithm to the public in the hopes that it will help other researchers in their work against age-related illness.

Show Me The Proof

ScienceDaily: Scientist uncovers internal clock able to measure age of most human tissues
Genome Biology: DNA methylation age of human tissues and cell types