Should Science Give Astronauts Genetic Superpowers for Space Travel?
What if people could just survive on sunlight like plants?
The admittedly outlandish question occurred to me after reading about how climate change will exacerbate drought, flooding, and worldwide food shortages. Many of these problems could be eliminated if human photosynthesis were possible. Had anyone ever tried it?
Extreme space travel exists at an ethically unique spot that makes human experimentation much more palatable.
I emailed Sidney Pierce, professor emeritus in the Department of Integrative Biology at the University of South Florida, who studies a type of sea slug, Elysia chlorotica, that eats photosynthetic algae, incorporating the algae's key cell structure into itself. It's still a mystery how exactly a slug can operate the part of the cell that converts sunlight into energy, which requires proteins made by genes to function, but the upshot is that the slugs can (and do) live on sunlight in-between feedings.
Pierce says he gets questions about human photosynthesis a couple of times a year, but it almost certainly wouldn't be worth it to try to develop the process in a human. "A high-metabolic rate, large animal like a human could probably not survive on photosynthesis," he wrote to me in an email. "The main reason is a lack of surface area. They would either have to grow leaves or pull a trailer covered with them."
In short: Plants have already exploited the best tricks for subsisting on photosynthesis, and unless we want to look and act like plants, we won't have much success ourselves. Not that it stopped Pierce from trying to develop human photosynthesis technology anyway: "I even tried to sell it to the Navy back in the day," he told me. "Imagine photosynthetic SEALS."
It turns out, however, that while no one is actively trying to create photosynthetic humans, scientists are considering the ways humans might need to change to adapt to future environments, either here on the rapidly changing Earth or on another planet. Rice University biologist Scott Solomon has written an entire book, Future Humans, in which he explores the environmental pressures that are likely to influence human evolution from this point forward. On Earth, Solomon says, infectious disease will remain a major driver of change. As for Mars, the big two are lower gravity and radiation, the latter of which bombards the Martian surface constantly because the planet has no magnetosphere.
Although he considers this example "pretty out there," Solomon says one possible solution to Mars' magnetic assault could leave humans not photosynthetic green, but orange, thanks to pigments called carotenoids that are responsible for the bright hues of pumpkins and carrots.
"Carotenoids protect against radiation," he says. "Usually only plants and microbes can produce carotenoids, but there's at least one kind of insect, a particular type of aphid, that somehow acquired the gene for making carotenoids from a fungus. We don't exactly know how that happened, but now they're orange... I view that as an example of, hey, maybe humans on Mars will evolve new kinds of pigmentation that will protect us from the radiation there."
We could wait for an orange human-producing genetic variation to occur naturally, or with new gene editing techniques such as CRISPR-Cas9, we could just directly give astronauts genetic advantages such as carotenoid-producing skin. This may not be as far-off as it sounds: Extreme space travel exists at an ethically unique spot that makes human experimentation much more palatable. If an astronaut already plans to subject herself to the enormous experiment of traveling to, and maybe living out her days on, a dangerous and faraway planet, do we have any obligation to provide all the protection we can?
Probably the most vocal person trying to figure out what genetic protections might help astronauts is Cornell geneticist Chris Mason. His lab has outlined a 10-phase, 500-year plan for human survival, starting with the comparatively modest goal of establishing which human genes are not amenable to change and should be marked with a "Do not disturb" sign.
To be clear, Mason is not actually modifying human beings. Instead, his lab has studied genes in radiation-resistant bacteria, such as the Deinococcus genus. They've expressed proteins called DSUP from tardigrades, tiny water bears that can survive in space, in human cells. They've looked into p53, a gene that is overexpressed in elephants and seems to protect them from cancer. They also developed a protocol to work on the NASA twin study comparing astronauts Scott Kelly, who spent a year aboard the International Space Station, and his brother Mark, who did not, to find out what effects space tends to have on genes in the first place.
In a talk he gave in December, Mason reported that 8.7 percent of Scott Kelly's genes—mostly those associated with immune function, DNA repair, and bone formation—did not return to normal after the astronaut had been home for six months. "Some of these space genes, we could engineer them, activate them, have them be hyperactive when you go to space," he said in that same talk. "When we think about having the hubris to go to a faraway planet...it seems like an almost impossible idea….but I really like people and I want us to survive for a long time, and this is the first step on the stairwell to survive out of the solar system."
What is the most important ability we could give our future selves through science?
There are others performing studies to figure out what capabilities we might bestow on the future-proof superhuman, but none of them are quite as extreme as photosynthesis (although all of them are useful). At Harvard, geneticist George Church wants to engineer cells to be resistant to viruses, such as the common cold and HIV. At Columbia, synthetic biologist Harris Wang is addressing self-sufficient humans more directly—trying to spur kidney cells to produce amino acids that are normally only available from diet.
But perhaps Future Humans author Scott Solomon has the most radical idea. I asked him a version of the classic What would be your superhero power? question: What does he see as the most important ability we could give our future selves through science?
"The empathy gene," he said. "The ability to put yourself in someone else's shoes and see the world as they see it. I think it would solve a lot of our problems."
This man spent over 70 years in an iron lung. What he was able to accomplish is amazing.
It’s a sight we don’t normally see these days: A man lying prone in a big, metal tube with his head sticking out of one end. But it wasn’t so long ago that this sight was unfortunately much more common.
In the first half of the 20th century, tens of thousands of people each year were infected by polio—a highly contagious virus that attacks nerves in the spinal cord and brainstem. Many people survived polio, but a small percentage of people who did were left permanently paralyzed from the virus, requiring support to help them breathe. This support, known as an “iron lung,” manually pulled oxygen in and out of a person’s lungs by changing the pressure inside the machine.
Paul Alexander was one of several thousand who were infected and paralyzed by polio in 1952. That year, a polio epidemic swept the United States, forcing businesses to close and polio wards in hospitals all over the country to fill up with sick children. When Paul caught polio in the summer of 1952, doctors urged his parents to let him rest and recover at home, since the hospital in his home suburb of Dallas, Texas was already overrun with polio patients.
Paul rested in bed for a few days with aching limbs and a fever. But his condition quickly got worse. Within a week, Paul could no longer speak or swallow, and his parents rushed him to the local hospital where the doctors performed an emergency procedure to help him breathe. Paul woke from the surgery three days later, and found himself unable to move and lying inside an iron lung in the polio ward, surrounded by rows of other paralyzed children.
Hospitals were commonly filled with polio patients who had been paralyzed by the virus before a vaccine became widely available in 1955. Associated Press
Paul struggled inside the polio ward for the next 18 months, bored and restless and needing to hold his breath when the nurses opened the iron lung to help him bathe. The doctors on the ward frequently told his parents that Paul was going to die.But against all odds, Paul lived. And with help from a physical therapist, Paul was able to thrive—sometimes for small periods outside the iron lung.
The way Paul did this was to practice glossopharyngeal breathing (or as Paul called it, “frog breathing”), where he would trap air in his mouth and force it down his throat and into his lungs by flattening his tongue. This breathing technique, taught to him by his physical therapist, would allow Paul to leave the iron lung for increasing periods of time.
With help from his iron lung (and for small periods of time without it), Paul managed to live a full, happy, and sometimes record-breaking life. At 21, Paul became the first person in Dallas, Texas to graduate high school without attending class in person, owing his success to memorization rather than taking notes. After high school, Paul received a scholarship to Southern Methodist University and pursued his dream of becoming a trial lawyer and successfully represented clients in court.
Paul Alexander, pictured here in his early 20s, mastered a type of breathing technique that allowed him to spend short amounts of time outside his iron lung. Paul Alexander
Paul practiced law in North Texas for more than 30 years, using a modified wheelchair that held his body upright. During his career, Paul even represented members of the biker gang Hells Angels—and became so close with them he was named an honorary member.Throughout his long life, Paul was also able to fly on a plane, visit the beach, adopt a dog, fall in love, and write a memoir using a plastic stick to tap out a draft on a keyboard. In recent years, Paul joined TikTok and became a viral sensation with more than 330,000 followers. In one of his first videos, Paul advocated for vaccination and warned against another polio epidemic.
Paul was reportedly hospitalized with COVID-19 at the end of February and died on March 11th, 2024. He currently holds the Guiness World Record for longest survival inside an iron lung—71 years.
Polio thankfully no longer circulates in the United States, or in most of the world, thanks to vaccines. But Paul continues to serve as a reminder of the importance of vaccination—and the power of the human spirit.
““I’ve got some big dreams. I’m not going to accept from anybody their limitations,” he said in a 2022 interview with CNN. “My life is incredible.”
When doctors couldn’t stop her daughter’s seizures, this mom earned a PhD and found a treatment herself.
Twenty-eight years ago, Tracy Dixon-Salazaar woke to the sound of her daughter, two-year-old Savannah, in the midst of a medical emergency.
“I entered [Savannah’s room] to see her tiny little body jerking about violently in her bed,” Tracy said in an interview. “I thought she was choking.” When she and her husband frantically called 911, the paramedic told them it was likely that Savannah had had a seizure—a term neither Tracy nor her husband had ever heard before.
Over the next several years, Savannah’s seizures continued and worsened. By age five Savannah was having seizures dozens of times each day, and her parents noticed significant developmental delays. Savannah was unable to use the restroom and functioned more like a toddler than a five-year-old.
Doctors were mystified: Tracy and her husband had no family history of seizures, and there was no event—such as an injury or infection—that could have caused them. Doctors were also confused as to why Savannah’s seizures were happening so frequently despite trying different seizure medications.
Doctors eventually diagnosed Savannah with Lennox-Gaustaut Syndrome, or LGS, an epilepsy disorder with no cure and a poor prognosis. People with LGS are often resistant to several kinds of anti-seizure medications, and often suffer from developmental delays and behavioral problems. People with LGS also have a higher chance of injury as well as a higher chance of sudden unexpected death (SUDEP) due to the frequent seizures. In about 70 percent of cases, LGS has an identifiable cause such as a brain injury or genetic syndrome. In about 30 percent of cases, however, the cause is unknown.
Watching her daughter struggle through repeated seizures was devastating to Tracy and the rest of the family.
“This disease, it comes into your life. It’s uninvited. It’s unannounced and it takes over every aspect of your daily life,” said Tracy in an interview with Today.com. “Plus it’s attacking the thing that is most precious to you—your kid.”
Desperate to find some answers, Tracy began combing the medical literature for information about epilepsy and LGS. She enrolled in college courses to better understand the papers she was reading.
“Ironically, I thought I needed to go to college to take English classes to understand these papers—but soon learned it wasn’t English classes I needed, It was science,” Tracy said. When she took her first college science course, Tracy says, she “fell in love with the subject.”
Tracy was now a caregiver to Savannah, who continued to have hundreds of seizures a month, as well as a full-time student, studying late into the night and while her kids were at school, using classwork as “an outlet for the pain.”
“I couldn’t help my daughter,” Tracy said. “Studying was something I could do.”
Twelve years later, Tracy had earned a PhD in neurobiology.
After her post-doctoral training, Tracy started working at a lab that explored the genetics of epilepsy. Savannah’s doctors hadn’t found a genetic cause for her seizures, so Tracy decided to sequence her genome again to check for other abnormalities—and what she found was life-changing.
Tracy discovered that Savannah had a calcium channel mutation, meaning that too much calcium was passing through Savannah’s neural pathways, leading to seizures. The information made sense to Tracy: Anti-seizure medications often leech calcium from a person’s bones. When doctors had prescribed Savannah calcium supplements in the past to counteract these effects, her seizures had gotten worse every time she took the medication. Tracy took her discovery to Savannah’s doctor, who agreed to prescribe her a calcium blocker.
The change in Savannah was almost immediate.
Within two weeks, Savannah’s seizures had decreased by 95 percent. Once on a daily seven-drug regimen, she was soon weaned to just four, and then three. Amazingly, Tracy started to notice changes in Savannah’s personality and development, too.
“She just exploded in her personality and her talking and her walking and her potty training and oh my gosh she is just so sassy,” Tracy said in an interview.
Since starting the calcium blocker eleven years ago, Savannah has continued to make enormous strides. Though still unable to read or write, Savannah enjoys puzzles and social media. She’s “obsessed” with boys, says Tracy. And while Tracy suspects she’ll never be able to live independently, she and her daughter can now share more “normal” moments—something she never anticipated at the start of Savannah’s journey with LGS. While preparing for an event, Savannah helped Tracy get ready.
“We picked out a dress and it was the first time in our lives that we did something normal as a mother and a daughter,” she said. “It was pretty cool.”