Two mountaineers are trying to recreate NASA’s twin study—on Mount Everest

NASA’s widely publicized twin study—which compared astronaut Scott Kelly’s bodily functions to those of his earthbound identical twin brother—is getting a follow-up in one of the most forbidding environments on Earth. Two experienced mountaineers are in the middle of a month-long expedition to Mount Everest, while their twins stay at sea level. The primary goal: to sequence DNA and RNA from their white blood cells and search for possible changes in gene expression.

The project is one of the most demanding high-altitude studies ever done, not least because it requires the climbers to take samples of their own blood, saliva, and feces under freezing conditions at an altitude of more than 7 kilometers—if they can manage it. So far, so good. The team, 20-year-old Dartmouth College sophomore Matt Moniz and 49-year-old professional climber Willie Benegas, has already taken three blood samples, one at Everest’s Camp 3 at an elevation of 7300 meters.

The project was inspired by NASA’s twin study, which looked for changes in Kelly’s organs, cognitive function, immune function, microbiome, proteins, metabolites, and genes while he spent a year aboard the International Space Station (ISS) starting in March 2015. His identical twin, retired astronaut Mark Kelly, was an ideal control who shares his brother’s DNA, and also has previous space experience.

The most intriguing early results suggest Scott Kelly experienced changes in the expression of thousands of genes; earlier this year, NASA reported that 7% of them—related to immune function, DNA repair, bone formation, and his body’s response to insufficient oxygen and abnormally high carbon dioxide levels in the blood—remained some 6 months after his return to Earth.

But those changes can’t be directly attributed to life in orbit; they could simply be the result of being in an extremely stressful environment, says Christopher Mason, a geneticist at Weill Cornell Medicine in New York City, who led the gene expression study. So, he recruited Moniz and Benegas for an Earth-side “control” experiment. Although Everest is quite different from the ISS, low oxygen levels, freezing temperatures, and strong feelings of isolation make for intensely stressful conditions.

While Moniz and Benegas ascend, their twins—Kaylee Moniz and Damian Benegas—will stay at sea level and serve as their controls. The fact that the Moniz twins are fraternal is “not ideal,” Mason says. (The Benegas twins are identical.) “But you still can control 50% of their genetics, which is better than comparing completely different people with no relation.”

The Everest twin study, although not officially part of the NASA research, will use the same protocol. The climbers are collecting blood and microbiome samples—stool, saliva, and secretions from their eyes—at Everest Base Camp (5364 meters), both before and after acclimatization climbs, then again at Camp 3 and possibly higher. They will use supplemental oxygen on the last phase of their ascent, from Camp 3 to Everest’s 8850-meter summit. That means their final blood samples won’t be directly comparable to those taken at lower elevations, but it does increase their chances of getting to the top. It also means, Moniz jokes, that he’ll be able to keep all his brain cells for grad school.

Tatum Simonson, a geneticist at the University of California, San Diego, who studies genetic adaptations to high altitude, says the study will offer “unique insights” into how humans respond to environmental stresses. But she cautions that because different conditions are being tested—high altitude oxygen deprivation versus microgravity—the NASA and Everest studies remain distinct.

“They may be compared, but it is important to keep the differences in mind.” One area of possible comparison, she says, is changes to gene expression in pathways that respond to low oxygen, which appeared in Kelly after his year in space and are likely to appear in the two climbers.

Moniz and Benegas plan to push for the summit around the middle of May, when early forecasts show a likely drop in wind. If anyone can pull it off, it may be the two of them: Benegas has made it to the top of Everest 11 times, and Moniz, a National Geographic adventurer of the year, climbed several 8000-meter peaks before the age of 19. “I love working on projects like this when I’m on expeditions,” says Moniz, who studies biomedical engineering. “[It] offers me a chance to give something back, enrich my mind.”

*Correction, 5 May, 11 a.m.: An earlier version of this story reported that both twin pairs were fraternal. That has been corrected to state that only the Moniz twins are fraternal.