NASA's Twin Study Is Already Showing Surprising Results

In 2015 and 2016, astronaut Scott Kelly spent almost a year, 340 consecutive days, in orbit around the Earth in the International Space Station to help NASA better understand the effects of long term space travel on humans. But, just as important to the study, his identical twin brother, Mark Kelly, a NASA retiree, stayed on Earth.

Both twins underwent an extensive series of medical tests before Scott's trip to provide a baseline for understanding the differences between the body on Earth and the body in space. Now, although NASA will be waiting as long as a year or more to publish the findings of the study officially, with the final consent of the Kelly brothers, there are initial findings that have made themselves clear: At least in Scott's case, extended space travel affects DNA.

Upon initial research into the changes in Scott's body vs the changes in Mark's, the first thing scientists noticed was that Scott's telomeres, the protective caps at the ends of DNA strands, had lengthened while Mark's had stayed basically the same. Scott's telomeres have since returned to normal size, though, indicating that this is a temporary change that is reversed upon return to normal gravity.

The second thing scientists have noticed is that while earthbound Mark experienced an increase in DNA methylation, a process where molecules known as methyl groups are added to DNA, Scott experienced a decrease in DNA methylation living in microgravity.

But now, what we would like to know is...

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