After A Year In Space, This Astronaut's Genes Are Expressed Differently Than Those Of His Twin

What does space do to your body? NASA is trying to find out.

Scott Kelly is teaching NASA a lot about space. The 54-year-old astronaut just got done spending 340 days aboard the International Space Station. When he came back, scientists noticed something unusual: about seven percent of Kelly's genes were expressing themselves differently than when he left. 


Kelly's gene phenomenon has exploded in the news, and scientists have been able to study it closely because of his twin brother, Mark. Since Mark and Scott had identical genes, and only Scott went to space, researchers are looking into the ways that space changes the body. So far, their findings have been fascinating. 

Mark (left) and Scott (right) Kelly.  NASA

"Scott's DNA did not fundamentally change," NASA said in a statement. "What researchers did observe are changes in gene expression, which is how your body reacts to your environment."

The Twins Study was performed by 10 research teams from around the country, who were trying to figure out how the body changes after a year in space. Kelly's one-year on the ISS is a good precursor for a three-year mission NASA hopes to soon launch to Mars. 

Those researchers found that 93 percent of Scott's genes became "normal" again shortly after he returned to earth. Seven percent, though, had changes related to his immune system, DNA repair and bone formation networks, among other things. DNA changes weren't the only differences in Scott's body, either. Last March, Scott was two inches taller when he returned from his mission than he had been when he left. Those changes were due to the absence of gravity in space and its effect on his spine, and have since subsisted. 

Other changes were noticed too: Scott's telomeres, the caps on the end of chromosomes, got longer. This is the opposite of what researchers expect. His gut bacteria also changed, which scientists believe is due to a different diet and environment. 

NASA still hasn't released the full results of its experiments, but its expected to in 2018. So far, Scott seems unphased.

"I did read in the newspaper the other day… that 7% of my DNA had changed permanently," Kelly told Marketplace. "And I'm reading that, I'm like, 'Huh, well that's weird.'"


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