Why do we age? –Logan, 12, Pullman, WA

Dear Logan,

It’s usually later in life that we see the more dramatic signs of aging, like gray hair, wrinkles, and lots of birthday candles on our cake. But we really start growing older from the time we are born.

The way humans change across the lifespan fascinates my friend Cory Bolkan, an associate professor of human development here at Washington State University.

“There isn’t really one factor, one theory, or one line of research that can explain aging,” Bolkan said. “It’s kind of an exciting area with lots of opportunities to explore.”

For example, some scientists are really curious about how people age in space versus here on Earth.

NASA astronaut Scott Kelly recently returned from a year-long mission aboard the International Space Station. Scientists are curious if conditions of space, like living in weak gravity or being around particular particles from outside the solar system, might change the way a person ages.

They are also interested in the things we can’t always see right away.

Scientists think part of the answer to your question may lie in our genes. So, they want to look at Scott’s DNA.

“Our genes contain information about us that’s been passed down from our parents, grandparents, and ancestors,” Bolkan said. They hold the instructions for hair color and skin color, for example.

Scientists are particularly interested in studying Scott because he also has an identical twin brother. That means they were born with DNA that is exactly the same. Scientists will zoom into the ends of their DNA and observe sections that we think might be linked to growing older.

But it’s not just our genes that play a part in why we age, Bolkan said.

“You can have two identical twins who share the exact same DNA,” Bolkan said. “You can look at them again decades later and you’ll see that genetically they are more different.”

She said this makes the answer to your question even more complex. Our environments interact with our genes, too.

There are certain things in our environment that can damage our genes. The damage can be a result of activities like smoking or not wearing sunscreen. This kind of activity can speed-up the aging process, Bolkan said. Our physical appearance changes as a result of “wear and tear” on our DNA.

While we haven’t pinpointed the exact answer to why we age, we are finding clearer answers to other questions about growing older.

For example, the power of our mind can change the way we age, Bolkan said. Studies have shown people with a positive outlook on aging actually tend to live longer.

“People say ‘I don’t want to get older, it doesn’t look like fun’,” Bolkan said. “But when you look at the research and you look at happiness, we are the happiest later in life.”

Perhaps some of your best birthdays will be the ones with the most candles on your cake.

Sincerely,

Dr. Universe

Got a science question? E-mail Dr. Wendy Sue Universe at Dr.Universe@wsu.edu. Ask Dr. Universe is a science-education project from Washington State University.