Spending a year in space can really change your outlook on life, but it can also change your gene expression.
Scott and Mark Kelly are identical twin brothers and are both astronauts. They’re helping NASA out with a study on how spending a year in space can affect the human body.
Scott left for the International Space Station in March 2015 and spent 340 days in space, the record for most consecutive days in orbit, while his brother Mark stayed on Earth. When Scott returned, NASA compared his genes to his brother’s and found he underwent an “unexpected” genetic change.
They found “hundreds of unique mutations.” These changes were in his metabolism, cognition, and immunity, among others. NASA says these changes are a result of “the stresses of space travel, which can cause changes in a cell’s biological pathways and ejection of DNA and RNA.”
Around 93 per cent of these changes were temporary. NASA reported that some returned to normal within hours of being back on Earth, while others took up to six months to level out. However, seven per cent of the changes in his genes have remained in the two years he’s been back on Earth. These changes relate to his “immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia”, the study says.
Scott himself took to Twitter to joke about the fact that his genes are no longer an exact match to his twin brother.
What? My DNA changed by 7%! Who knew? I just learned about it in this article. This could be good news! I no longer have to call @ShuttleCDRKelly my identical twin brother anymore. https://t.co/6idMFtu7l5
— Scott Kelly (@StationCDRKelly) March 10, 2018
However, since publishing these preliminary findings NASA has made it clear that Scott’s DNA and genetic relationship have not fundamentally changed, but his gene expression has.
“Mark and Scott Kelly are still identical twins,” says NASA. “Scott’s DNA did not fundamentally change. What researchers did observe are changes in gene expression, which is how your body reacts to your environment. This likely is within the range for humans under stress, such as mountain climbing or SCUBA diving. The change related to only 7 percent of the gene expression that changed during spaceflight that had not returned to preflight after six months on Earth. This change of gene expression is very minimal. We are at the beginning of our understanding of how space flight affects the molecular level of the human body.”
The study is important for more reasons than just seeing if a pair of twins end up identical after space travel. It is a stepping stone to a mission to Mars, which takes up to three years. It will help NASA understand the toll space has on the body during long-duration flights and help them figure out how to get humans safely to Mars. More comprehensive results for this twins study will be released by NASA later this year.