Unhealthy issues occur to a human physique in zero gravity. Simply take a look at what occurs to astronauts who spend time in orbit: Bones disintegrate. Muscular tissues weaken. So does immunity. “Once you go up into area,” says Saïd Mekari, who research train physiology on the College of Sherbrooke, in Canada, “it’s an accelerated mannequin of growing older.” Earthbound experiments mimicking weightlessness have revealed comparable results. Within the Seventies, Russian scientists immersed volunteers in bathtubs lined in a big sheet of waterproof material, enabling them to drift with out being moist. In a few of these research, which lasted as much as 56 days, topics developed severe coronary heart issues and struggled to regulate their posture and leg actions.
Weightlessness hurts us as a result of our our bodies are fine-tuned to gravity as we expertise it right here on Earth. It tugs at us from start to demise, and nonetheless our intestines keep firmly coiled of their stack, blood flows upward, and our backbone is able to holding up our head. Unnatural contortions can throw issues off: Folks have died from hanging the wrong way up for too lengthy. However as a common rule, the fixed push of g-force on our physique is part of life that we hardly ever discover.
Or a minimum of, that’s what scientists have all the time thought. However there may be one other risk: that gravity itself is making some folks sick. A brand new, peer-reviewed idea means that the physique’s relationship with gravity can go haywire, inflicting a dysfunction that has lengthy been a troubling thriller: irritable bowel syndrome.
This can be a rogue thought that’s removed from extensively accepted, although one which a minimum of some specialists say can’t be dismissed outright. IBS is a quite common ailment, affecting as much as an estimated 15 % of individuals in the USA, and the signs may be brutal. Individuals who have IBS expertise belly ache and gasoline, really feel bloated, and infrequently have diarrhea, constipation, or each. However no precise reason behind IBS has been pinned down. There’s proof behind many competing theories, reminiscent of early-life stress, weight loss plan, and even intestine infections, however none has emerged as the only rationalization. That could be a drawback for sufferers—it’s troublesome to deal with a situation if you don’t know what to focus on.
Brennan Spiegel, a gastroenterologist at Cedars-Sinai Medical Heart, in Los Angeles, has a special thought: Folks with IBS are hypersensitive to gravity on account of any variety of components—stress, weight achieve, a change within the intestine microbiome, unhealthy sleep patterns, or one other habits or harm. The concept got here to him after watching a relative confined to a nursing-home mattress develop basic signs of IBS. “We’re upright organisms,” he advised me. “We’re probably not imagined to be mendacity flat for that lengthy.” The speculation, revealed late final 12 months in The American Journal of Gastroenterology, is simply that, a speculation. Spiegel hasn’t performed any experiments or affected person surveys that time to a “mismatch” in our physique’s response to gravity as the reason for IBS, although the mechanics are all based mostly in agency science. However a part of what makes the speculation so alluring is that it’d embody the entire different standard explanations for the illness. “It’s meant to be a brand new mind-set about previous concepts,” he mentioned.
So precisely how would somebody’s relationship with gravity get off-kilter? Take into account serotonin, a chemical that carries messages from the mind to the physique. Spiegel sees serotonin as an “anti-gravity substance” due to the function it performs in so many vital bodily features influenced by g-force, reminiscent of blood stream. Serotonin may cause blood vessels to slim, slowing circulation. It will possibly make sure muscle tissues contract or chill out. It’s additionally essential to digestion, serving to with bowel perform, eliminating irritating meals, and regulating how a lot we eat. With out serotonin, gravity would flip our intestines right into a “flaccid sac,” Spiegel writes. As a result of 95 % of the physique’s serotonin is produced within the intestine, if ranges spike or plummet from components reminiscent of stress, then the chemical’s doable dealing with of gravity could be thrown into chaos, affecting digestion. The consequence, he theorizes, is IBS.
Different elements of our physique that reply to gravity can be in on the issue. We’re hardwired to react negatively to conditions through which the pull of gravity would possibly hurt us; stroll to the sting of a cliff and your physique will let you know one thing. The amygdala in our mind is vital to concern responses, and stress of assorted sorts may cause it to enter overdrive. Spiegel thinks that when stress taxes the amygdala, an individual begins overreacting to potential threats, together with gravity. The digestive points that make up IBS are a manifestation of that overreaction. Positive sufficient, folks with IBS have been proven to have a hyperactive amygdala.
That’s hardly something near proof. The thought that this painful and extended situation could possibly be a gravity dysfunction is a serious stretch, counting on a renegade interpretation of primary biology. “Folks simply assume I’m loopy,” Spiegel mentioned. Lots of his fellow medical doctors usually are not offered on the concept. The gravity speculation is one other in a protracted parade of unconvincing theories about IBS, Emeran Mayer, a gastroenterologist at UCLA, advised me. He’s heard all of them: “It doesn’t exist; it’s a hysterical trait of neurotic housewives; it’s irregular electrical exercise within the colon.” He added, “I don’t assume there’s some other illness that has gone by way of these peaks of attention-grabbing new theories.”
Spiegel’s thought has clear holes. If a defective response to gravity triggers IBS, says David C. Kunkel, a gastroenterologist at UC San Diego, you then would anticipate to see increased charges of IBS amongst populations dwelling at sea degree versus at excessive altitudes, the place g-force is barely weaker. However that doesn’t appear to be the case: A couple of quarter of Peruvians stay excessive within the mountains and most Icelanders stay at sea degree, but each international locations have excessive charges of IBS. Likewise, IBS charges seem to lower with age, “which might not be anticipated if the illness was attributable to a continuing gravitational pressure,” Kunkel advised me.
Spiegel is conscious that the gravity speculation has little assist within the discipline and no proof. However the gravity speculation has some logic behind it. The truth that the weightlessness of area journey can drastically change the physique lends credence to the concept that different shifts in our relationship to gravity might do the identical, says Declan McCole, a biomedical scientist at UC Riverside.
And the intestine could also be significantly delicate to gravity modifications. McCole has discovered that weightlessness made epithelial cells—which line the intestine and cease invaders from getting into the physique—simpler to evade. So if our inside chemistry can change in a approach that makes us hypersensitive to gravity, then, to McCole, it stands to motive that such a shift might hit the intestine exhausting. He’s much less certain of whether or not that hypersensitivity exists. If it does, then why haven’t we recognized any chemical substances that assist deal with gravity, as we now have for concern or intercourse drive or starvation? That molecule could certainly transform serotonin, however proper now there’s no proof.
The gravity speculation actually issues solely whether it is significant for folks with IBS. And that’s not assured. Tying the very actual ache of IBS to such a fantastical thought could appear nearer to mythology than drugs, leaving sufferers feeling dismissed or belittled. Or they could throw up their palms in despair and put together for a lifetime of ache: If the immovable pressure of gravity is the enemy, then why hassle combating?
But when there may be some fact to it, then the speculation might additionally present a doable beginning place for therapies. A few of Spiegel’s strategies are already widespread, reminiscent of weight reduction and drugs that lower serotonin, however he additionally advocates for some gravity-specific therapies. “I do speak about it with my sufferers,” Spiegel mentioned. “I like to recommend sure yoga poses; I like to recommend tilt tables.” Individuals who have IBS could balk at his extra radical concepts, reminiscent of shifting to a better altitude or farther from the equator.
The gravity speculation could by no means be something greater than a speculation. We have now a protracted approach to go earlier than really figuring out whether or not the human physique can develop a hypersensitivity to gravity that may make us sick, or whether or not a few of us are higher geared up to deal with gravity than others. However the weight of proof is sufficient to make us assume twice earlier than ignoring the concept that our physique’s relationship to gravity can go awry—together with these of us not dealing with IBS. If gravity would possibly contribute to IBS, why not different illnesses too? After which, why can’t it even be harnessed for good? Mekari and his colleagues not too long ago discovered that mendacity at a six-degree downward angle sped up response occasions to cognition exams—pointing to a doable hyperlink between gravity and government functioning. Antigravity treadmills, which assist astronauts put together for weightlessness, are being studied for the remedy of cerebral palsy, Parkinson’s illness, and sports activities accidents.
All of those unknowns about gravity can really feel haunting. Life on Earth has modified so much since its first kinds appeared about 4 billion years in the past, however by way of all of it, gravity has seemingly remained fixed—maybe the only factor that connects each organism that has ever lived. What if there’s nonetheless a lot we now have to study what it’s doing to us? In spite of everything, proper now your physique is dealing with gravity, simply because it has been for each different second of your life. Maybe it might be weirder if gravity wasn’t doing something to us over time. “Each fiber in our physique is straining to handle this pressure,” Spiegel mentioned. You don’t have to spend 56 days in a tub to determine that out.
