What is it to breathe? Find out in this episode of Uncertainty Principle, the Soundcloud based science podcast with transcript below!
What is it to breathe? Certainly those of you receiving this are familiar with the human action of breathing, unless you are some extra-anthropic entity without the need to breathe. I will, however, assume that you are not, and that you do, indeed, require breath. Breathing in its most literal sense is the action of consuming oxygen, and subsequently expelling poisonous carbon dioxide. That’s about as far as most people’s knowledge of breathing goes. And who can blame them? It seems so, trivial to explore something that we do without even thinking. But why? It is one of the first things that you do outside of the womb, and its ceasing is an indication of death. Between these two, you hardly ever stop doing it for more than a minute.
Breathing isn’t something overlooked by humans. Antiquity is riddled with the association between breathing and life. The ancient Hebrews wrote in the creation myth of the Book of Genesis chapter two verse seven,
“And Jehovah God formeth the man – dust from the ground, and breatheth into his nostrils breath of life, and the man becometh a living creature.”
Similarly, it is written in the Greek creation myth,
“Prometheus shaped man out of mud, and Athena breathed life into his clay figure.”
Even English, holds clues to this ancient correlation. The Greek word “pneuma”, which we now use in words like, pneumonia – an illness of the lungs – means “breath”, and also, “spirit of man”. Moreover, the word “spirit” comes from the latin word for breath; “spiritus”.
For modern humans, the relationship between breath and life is so obvious that it’s easy to overlook. Among the list of that which we associate with life – besides breath – are simpler things the ancients would have recognized like blood, food, water, and sex. Our list is longer and more sophisticated; we can add things like oxygen, nitrogen, atmospheric pressure, mild temperatures, an abundance of nutrients, sleep, a working heart, an undamaged brain, and so, so much more. But in a moment of crisis, one of the first things we check in an unconscious person is whether or not they are still breathing.
Among all of that which is needed to keep us alive, breathing, next to a beating heart, is one of the most immediate concerns of our body. That’s why holding your breath is so unpleasant – because you need it all the time. Think about it, you have to unceasingly breathe just to stay alive, but most of us succeed at that for years without even thinking about it. Others aren’t so lucky.
There is a German fable of a nymph named Ondine, who, if she falls in love with a mortal, will lose her immortality. And that she did – with a knight named Lawrence. Upon their marriage, he pledged to Ondine,
“My every waking breath shall be my pledge of love and faithfulness to you.”
But Lawrence was not faithful, and upon discovering his infidelity, Ondine was furious that she had sacrificed her immortality for this man. She cursed him to never sleep again, for if he slept, he would forget to breathe, and die. What a terrible affliction! Thankfully Ondine doesn’t curse people anymore. Or does she?
There is a very real medical disorder called Congenital Central Hypoventilation Syndrome. Known, more informally, as Ondine’s Curse, though we can be sure that those it affects were not cursed by a betrayed goddess. CCHS, as it is called, is an incredibly rare disorder in which the body loses its autonomic ability to regulate respiration. Being awake, you can breathe on your own, but when you go to sleep, your body has to regulate your breathing for you. Victims of CCHS lack this regulation, and like Sir Lawrence, “forget” to breathe when they sleep. It’s not clear how rare Ondine’s Curse is, as few studies have been done on large and diverse populations surrounding the prevalence of this disorder, but it is rare enough that it’s unlikely you know anybody with it. The disorder is treatable, but if left untreated, it can be a slippery slope to a fate like that of Sir Lawrence.
So let’s be thankful that the vast majority of us don’t have to worry about breathing. But why do we have to breathe, how do we breathe, and…what do we breathe. Questions with less obvious answers than one would think. To answer these, we have to go back to the beginning of life itself, on Earth.
This would be around four billion years ago, shortly after the earth’s formation, but still after the crust had cooled. The planet back then would have been unrecognizable as your home. The continents that we now recognize did not yet exist as tectonic activity has shifted the earth’s crust since, and continues to do so. There would have been no foliage – looking outside, it’s hard not to see a plant or some sign of life. The planet would have been a barren rock. And of course: you wouldn’t have been able to breathe. The earth’s original atmosphere consisted of probably helium and hydrogen. These gases wouldn’t have stayed on the earth because its gravity isn’t strong enough to hold on to light gases. On top of this, the planet had not yet developed a magnetic field to block the solar wind from our host star. These gases would easily have been blown away by the sun.
Later on, heavy volcanic activity would expel gases from the inner earth, creating our second atmosphere. There were some familiar gases like nitrogen and carbon dioxide (most likely in levels different than that of today), but also more poisonous gases like methane, chlorine, and carbon monoxide. There was, as of yet, little to no oxygen in the atmosphere, but there was gaseous water. As the earth cooled, the water became liquid, forming the earth’s oceans. It is from here that life arose. The arrival and evolution of life on our planet is a much more in-depth story that we will come back to in the future, but what we want to know is how it contributed to our atmosphere. For most of the history of this planet, life was incredibly simple; unicellular and microscopic. The most complex organism back then wouldn’t have been as complex as the simplest organism now. From this period of our history, the first plants arose, inhaling the carbon dioxide rich atmosphere and turning it into oxygen. The earth had begun to breathe.
It is then fair to ask why humans don’t breathe in the same way – inhaling carbon-dioxide and exhaling oxygen. Moreover, oxygen is somewhat poisonous to cells, modern humans can actually die of oxygen poisoning. So the early plant life of this planet was exhaling poison. Luckily, we don’t breathe in that much oxygen. Most of the modern atmosphere is made of nitrogen, and about a fifth of it is oxygen, and out of the oxygen we inhale we only use a fraction. Too much of it can be intoxicating. So what happened long ago that turned a substance harmful to life into that which we most immediately need? Efficiency is what happened. The process for breathing in oxygen – aerobic breathing – acquired much more energy than the previous anaerobic processes. The bacteria that evolved the ability to breathe oxygen obtained more energy than their predecessors. This bacteria eventually merged with other cells to become mitochondria, a cellular organ seen in most modern cellular life. When we breathe, it is the mitochondria that is using that energy. You should think of your body less as an organism and more like a hive. You have trillions of cells, and all of them are individually alive. When you breathe, your bloodstream takes the oxygen, and shuttles it around your body to your cells so they can stay alive. You live because some proto-bacteria learned a new trick, and converged with other life forms. When you breathe, your whole body takes a breath.
We could also say that the earth breathes because all the life on it is made from it. When we and the other plants and animals breathe *breath* that is the earth taking a breath. But we are in a special form of existence called life. Does anything else breathe?
Not much else does, but I like to think that the universe on its grandest scale is breathing. But allow me to explain before you go off telling people that the universe is a living organism. Cosmology and astrophysics has long been interested in the ultimate fate of our universe. Edwin Hubble in the 1920’s not only proved that the universe contained more than one galaxy, but that the space itself was expanding, and the distance between galaxies was increasing. This was the primary observation that led to the big bang theory – that the universe as we know it started from a single point and “exploded” so to speak, outward. One theory about the universe’s fate is called the oscillating universe. This idea states that if there is enough gravity in the universe, it’s expansion will stop and reverse, bringing everything back together again. Then the process repeats. The universe exhales in a big bang and inhales in a big crunch. In this sense, the whole universe is breathing like us.
Though this theory is still on the table, but it is not the likely scenario. Observation of distant galaxies has lead astronomers to the conclusion that the universe’s expansion is accelerating. We don’t really know why – it is a great mystery of science to be solved. If this is true, then the universe is just a single outward breath, and it will disperse into nothing… But it is in such a distant future, it is hardly worth the worry.
On this somber note I leave you, but go outside and breathe. The trees are doing it, the flowers, the grass, and all of the animals living in your backyard. Enjoy the atmosphere that you have, and breathe deeply, because earth is the only place in the universe, so far, where you can go outside and breathe with ease.
Thanks for listening, and keep exploring.