“I think that we are like stars. something happens to burst us open; but when we burst open and think we are dying, we’re actually turning into a supernova. And when we look at ourselves again, we see that we’re suddenly more beautiful than we ever were before.” C. Joybell C.
Hydrogen is formed into helium, and helium is built into carbon, nitrogen and oxygen, iron and sulphur - everything we're made of. When stars get to the end of their lives, they swell up and fall together again, throwing off their outer layers. If a star is heavy enough, it will explode in a supernova.
Our bodies are made of remnants of stars and massive explosions in the galaxies. Everything we are and everything in the universe and on Earth originated from stardust, and it continually floats through us even today. It directly connects us to the universe, rebuilding our bodies over and again over our lifetimes.
The residual stardust finds its way into plants, and from there into the nutrients that we need for everything we do—think, move, grow. And every few years the bulk of our bodies are newly created.
We tend to think of our bodies changing only slowly once we reach adulthood. In fact, we're changing all the time and constantly rebuilding ourselves.
The skin, for example, is our largest organ. To keep alive, our cells have to divide and grow. We're aware of that because we see children grow. But cells also age and eventually die, and the skin is a great example of this. It's something that touches everything around us. It's also very exposed to damage and needs to constantly regenerate. It weighs around eight pounds and is composed of several layers. These layers age quickly, especially the outer layer, the dermis. The cells there are replaced roughly every month or two. That means we lose approximately 30,000 cells every minute throughout our lives, and our entire external surface layer is replaced about once a year.
Very little of our physical bodies lasts for more than a few years, something we might find hard to grasp each day as we look in the mirror. But we're not fixed at all. We're more like a pattern or a process.
The spiral in a snail's shell is the same mathematically as the spiral in the Milky Way galaxy, and it's also the same mathematically as the spirals in our DNA. It's the same ratio that you'll find in very basic music that transcends cultures all over the world. Joseph Gordon-Levitt.
Every tissue recreates itself, but they all do it at a different rate. We know through carbon dating that cells in the adult human body have an average age of seven to ten years. That's far less than the age of the average human, but there are remarkable differences in these ages. Some cells literally exist for a few days. Those are the ones that touch the surface. The skin is a great example, but also the surfaces of our lungs and the digestive tract. The muscle cells of the heart, an organ we consider to be very permanent, typically continue to function for more than a decade. But if you look at a person who's 50, about half of their heart cells will have been replaced.
Our bodies are never static. We're dynamic beings, and we have to be dynamic to remain alive. This is not just true for us humans. It's true for all living things.
Cells die and rebuild all the time. We're literally not what were a few years ago, and not just because of the way we think. Everything around us does this.
Nature is not outside us. We are nature.
Read more: Living with the stars: how the human body is connected to the life cycles of the Earth, the planets, and the stars. Karel Schrijver and Iris Schrijver.