In reality, their DNA hasn’t been identical for most of their lives. We humans accumulate random mutations throughout our genomes as we age, and the chances that Mark and Scott’s genetic sequences were randomly modified in exactly the same way are astronomically small. Mark and Scott Are Not IdenticalĪnother somewhat alarming-sounding finding is that Scott Kelly’s DNA “ no longer matches that of his identical twin.”įor anyone familiar with genetics, this is possibly the most obvious statement one could make. Certainly, spending a year in microgravity with reduced oxygen and increased radiation levels could cause that type of change. Indeed, seeing such changes in expression is not at all unusual-it happens each time we get sick, or in response to environmental factors. “Nonetheless, this number is likely within the range for humans under stress, such as climbing a mountain, or SCUBA diving.” “We had no idea what to expect, and this is the first experiment of its kind, so this sets the bar for future studies of astronauts,” Mason says. That these levels of expression haven’t boomeranged to pre-spaceflight values is humongously different than saying Kelly’s DNA didn’t “ return to normal after a sojourn in space.” “Seven percent of the genes that changed their expression during spaceflight were still altered after six months back on Earth,” says Weill Cornell Medicine’s Christopher Mason, who led the analysis. The NASA result everyone is freaking out about actually measured Scott Kelly’s expression levels, and it found that-not surprisingly-spaceflight affects how much expressing certain genes do, particularly those involved in immune function, DNA repair pathways, and bone growth. This animated time line, made of paper, covers some important milestones in space exploration, weaving in astronauts' thoughts about Earth. It’s those patterns of expression that produce hearts, brains, eyeballs, and other things, kind of like using the same set of ingredients to cook up vastly different dishes. Within each of us, most of our cells are otherwise genetically identical, but their genes are expressed at different levels. Most mutations, however, go unnoticed (the one that confer superpowers are a different story).Įxpression levels, on the other hand, reflect whether genes are turned on or turned off. Mutate the wrong letter, or sequence of letters, and it can be mildly annoying, like our favorite ducking autocorrect, or it can be extremely bad news, like the mutations that allow tumors to proliferate. Genetic sequences are like strings of letters arranged just so, and they are in charge of producing proteins. So, no, seven percent of Kelly’s DNA is not mutated after his year in space, which makes sense if you keep in mind that humans and chimps have genetic sequences that differ by less than 2 percent, and individual humans-even completely unrelated strangers-differ by about 0.1 percent.
“I, too, am concerned about how the stories coming out are being sensationalized,” says Colorado State University’s Susan Bailey, who leads one of the research groups studying the twins. The space agency says that papers detailing the findings will be published later this year, and for now, the press is mostly relying on some vague wording and other information contained in a NASA release. Among the dimensions surveyed were cognitive ability, immune system function, and genetics. That study, which involves multiple independent research groups, compared Scott with his twin brother Mark (also a NASA astronaut) and looked for changes caused while Scott spent a year aboard the International Space Station, a mission that ended in March 2016. The story Kelly is referring to, and many more, misrepresent the results of a study NASA commissioned on the effects of spaceflight by confusing changes in genetic sequence with changes in gene expression levels.
Well, and we hate to spoil the fun, but no.
Hosted by Will Smith, ONE STRANGE ROCK is a mind-bending, thrilling journey exploring the fragility and wonder of our planet.
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