Breath: Divine Gas In a Smart Body

The word breath most often refers to the air we pull in to and pump out of our lungs (or to the action of doing so) as in “Take a deep breath.” But we also give the same word loftier qualities in phrases such as “the breath of life” and in practices like yoga that view the breath as a source of health and peace. Other traditions and languages also have words for breath in both these ordinary and spiritual senses, such as Latin spiritus, Hebrew ruach, and Chinese qi.

breath spirit (soundofheart.org)

soundofheart.org

But what about the breathing body itself? Unless we are wheezing or short of breath, we usually take the smooth coordination of our lungs, diaphragm, membranes, and blood cells as unremarkable. But let’s refocus our wonderment for a moment. The air is, when you come down to it, just a mix of gasses, but our body’s ingenious respiration of them is a process to appreciate.

We breathe in air because it contains one gas that we must have: oxygen. We know that. Less familiar, though, is the step-down system that has evolved to make the most of the fact that, like all gasses, oxygen spreads out from wherever there is more of it to where there is less of it. Thanks to this step-down dispersal and our flowing  blood, we move oxygen from the air outside of us to every cell that is waiting for it, all several trillion—that’s 000,000,000,000—of them.

Why oxygen? Its electrons are arranged in such a way that it interacts eagerly and often with other elements. It’s a potent extrovert. The body’s cells may get their nourishment from food molecules but not unless they also have oxygen handy to break those molecules down. That would be like our eating dinner without any acid in our stomach to digest it. No nourishment. Without oxygen, cells go hungry.

But a little oxygen goes a long way. The numbers surprised me. Only about twenty percent of the air that we breathe is oxygen. The rest is nitrogen and a percent or two of other gasses. And of that twenty percent of oxygen that we inhale, we actually use only about a quarter of it. The rest goes out again. Our inhalation is twenty percent oxygen; we exhale fifteen percent.

Once it is in our lungs, oxygen must get across the lung’s membrane to the blood stream that will move it around the body. The amount of oxygen in the lung might not seem like much, but it is more than remains in the oxygen-depleted blood that is returning towards the lungs through the veins. So the new oxygen steps down across the thin membrane to the empty hemoglobin molecules in the blood cells for the ride to the rest of the body.

As this convoy of oxygenated blood flows near, say, a finger, the oxygen detaches from the hemoglobin, steps down once more across a membrane to a cell itself, and goes to work on the food particles. In the process, extrovert that it is, oxygen combines to form unusable carbon dioxide, crosses the cell membrane back out to some empty passing hemoglobin that just dropped off new oxygen elsewhere, rides the vein back to the lungs, gets off again, and is exhaled back out to air. Like riding the bus you took to work back home at the end of the day.

I argue for the wonderment of a distribution system that pulls in air-borne oxygen in an endless rhythm, arranges for it to disperse itself across strategic membranes, loads it on to the blood for transport to a million million cells that it will help nourish, after which it returns the way it came in. Our stunning respiration makes oxygen look good—even divine.

 

Plants as Aliens

Plants are so familiar to us that we don’t see them very well. We look at them and think about them according mostly to how we use them—for food and beauty. To shift our perspective, I’ll look at plants as if they were strangers from another planet, as plant-aliens. Making them weirder may make them more vivid.

  • Plant-aliens don’t eat anything. They make their own food. For that purpose they anchor themselves to a water source and grow their own solar panels.
  • Plant-aliens follow a clock that is geared only to the sun light and the seasons. Small plants push out leaves and flowers quickly in early spring so that they can catch maximum sunlight before the slower growing leaves on the trees above them plunge them into shade.
  • Unlike the many animals that cooperate so they can secure food, plant-alien food makers have little reason to be social. They don’t appear to react to each other at all as they seek out the sun. In fact, however, research is showing that their root systems commune with fungi about soil conditions and they share nutrients.
  • Many plant-aliens are giants. They tower over all animals.
  • Through their sophisticated plumbing and evaporation mechanisms, tree-aliens pull water up long distances without using any kind of pump. Animals, on the other hand, must all use small pumps just to keep fluids moving inside their fragile bodies.
  • Life below freezing (blendspace.com)

    Life below freezing
    (blendspace.com)

    Plant-aliens survive sub-freezing temperatures that last for weeks or months. They get as cold as the frozen earth around them. Animals can’t survive if they get that cold; hibernating animals cling to a slow metabolism that keeps them above freezing.

  • One process that plant-aliens do share with animals is sexual reproduction. Their equipment for doing so, however, is a little kinky. An individual plant-alien may contain flowers with structures that are male or female or both or that change from one to the other.
  • Plant-aliens breathe in carbon and exhale oxygen. Animals do the reverse.
  • Plants-aliens have successfully colonized the earth. They occupy the coldest and hottest zones, they outnumber animals and they are both larger and smaller than we are. And we animals are at their mercy for our food and oxygen.*

Plants are so different from us and so impressive that it’s actually not too difficult to portray them as aliens. And after that exercise, it’s pleasant to see them again as our comfortable companions and allies. I wonder if they feel the same way about us.

 

*With appreciation for David Attenborough’s The Private Life of Plants (1995)

Life Before Fossils

Most of what we think of as fossils—old bones, hardened bits of plants, impressions of leaves—go back no more than 600 million years. Yet life on the planet is about 3.8 billion years old, more than six time further into the past. How do we know that? What evidence do we have of life on earth so much earlier than the oldest fossilized bones?

Stromatolites in Australia today, looking much as they did 3.5 billion years ago. (stromatolites.weebly.com)

Stromatolites in Australia today, looking probably much as they did 3.5 billion years ago.
(stromatolites.weebly.com)

One might think that there are older fossils that haven’t been found yet. But in fact there were no animals and plants at all before 600 mya. For about the first 3 billion years—much of the entire course of life on the planet—almost all life was tiny, even microscopic.

(One exception is fossilized stromatolites, hardened layers of bacterial cells piled in paddy-shaped colonies, seen today in their living versions at Shark Bay, Australia. Stromatolites thrived globally around 1.25 billion years ago but date back 2 billion years before that.)

Stromatolites in Australia, probably looking much as they did 3.5 billion years ago. (www2.estrellamountain.edu)

Microfossils from 3.5 billion years ago (www2.estrellamountain.edu)

So instead of digging through dirt, today’s paleontologists start by searching for the oldest rocks. Samples of rocks that formed up to four billion years ago from Australia, Greenland, South Africa and elsewhere are sliced, studied under a microscope, and tested with chemicals. Scientists find microfossils, tiny creatures’ cell walls that have mineralized into tough material. Or they find chemical smears of carbon or the products of the earliest photosynthesis. A recurring challenge is to figure out whether such traces are signs of early organisms or only part of the rock itself.

banded iron (britanica.com)

Banded iron (britannica.com)

A less direct but more common sign of early life is oxygen, especially as it appears in bands of rust in rocks. The same bacteria that built the stromatolites gave off oxygen as a waste product, most of which was absorbed by iron in the oceans. The result was masses of rust that eventually formed in bands in rocks, most abundantly around 2.4 bya. It wasn’t until 2 billion years ago that enough iron had turned to rust so that bacterial oxygen was no longer absorbed by the metal and instead accumulated in the atmosphere.

Who does this kind of ancient detective work? We’ve come a long way from Indiana Jones. The field today consists of hybrids of the disciplines that I’ve always been familiar with. For example, the curriculum in Geobiology at the California Institute of Technology includes the following course titles: Earth’s Biogeochemical Cycles, Isotopic Biogeochemistry, Microbial Metabolic Diversity, Paleooceanography, and Geobiological Constraints on Earth History.

As these titles suggest, the study of the history of early life parallels how we view ecology today: the state of living things is inseparable from the state of the planet; a change in one always means a change in the other, back and forth, continually.