How can you trace minerals from supernovas to our teeth and bones? Isn’t the calcium that make up our bones produced during our gestation? How is that connected to a supernova from potentially millions of years ago?
In: Biology
>Isn’t the calcium that make up our bones produced during our gestation?
The calcium us PUT there during gestation, but that’s not where the Ca comes from. Ca comes from stellar nucleosynthesis and supernovae. The heavier elements come from neutron star mergers and the subsequent massive explosions that occur from them.
The elements just exist and are here from when Earth formed from dust floating around in a nebula, they’re just exchanged and recycled.
I like this video about where stuff comes from: [https://www.youtube.com/watch?v=lInXZ6I3u_I](https://www.youtube.com/watch?v=lInXZ6I3u_I)
Imagine elements like Lego bricks. Let’s say calcium is a 2×2 white brick. When stars explode, it’s so hot that matter, or “plastic” for this metaphor, fuses together to make a new permanent brick. A star exploded a long time ago, fusing a bunch of these new 2×2 bricks.
As time goes on, these bricks get linked up to other bricks of various types. These are various molecules that contain calcium, but aren’t like bones and teeth yet. Your digestive system has enzymes and other processes that look for those specific Lego bricks linked to others, and pull them out. Then the body puts those bricks together in a way that forms bones and teeth.
I don’t remember my biochem enough to give more details about the actual molecules themselves, but this feels ELI5 enough.
Calcium is a relatively common element, being around 3% of Earth’s crust (while of the human body, around 1.3% is calcium). Most if has been created as a part of the silicon-burning process; when a star has fused up much of the lighter elements in it, leaving mostly silicon. Though it’s not silicon itself that is fused straight into calcium. Rather silicon fuses with an alpha particle (that is; helium) and forms sulfur and sulfur fuses with an alpha particle and forms argon and argon fuses with an alpha particle and forms calcium. Subsequently, that’s also the order of their abundance in the universe; silicon is more common than sulfur which is more common than argon which is more common than calcium.
To fuse calcium requires so much concentrated energy that the human body can not do it, nor can it fuse or split any element at all. We get all the calcium in our body from our food (or, in gestation, from our parent’s blood). It’s typically not as free calcium that our body can instantly use, rather it’s as e.g. calcium salts, which our body digests.
Most of all matter was made in a star somewhere and somewhen. The calcium in your bones is built from atoms that were created in a star. Most of you is.
The calcium in your skeleton when you were born came from your mother, who got it from food, drink, and maybe supplements. That calcium, in turn, came from plants and animals that got it from their food or from the soil. The calcium in the soil came from rocks and bones. And *that* ultimately was made by a supernova billions of years ago.
See, matter is never created or destroyed. Every atom in the universe has been here since the Big Bang. The calcium in your bones and teeth is made up of atoms that used to be part of something else. Many somethings, in fact. Maybe even a dinosaur at one point. Isn’t that cool?
Calcium is a chemical element. The kind of things that happen in your body can bind calcium to other elements or and tear it away from them, but cannot create or destroy it. Therefore, all the calcium that’s currently in your body came from somewhere else. As an adult, you eat foods that contain calcium, and your body separates the calcium out and puts it to use. As a baby, your mother’s body did the digesting for you, and you got your calcium from her. These are all facts that scientists have observed repeatedly and proven exhaustively.
The remaining question then is, where did calcium come from originally? The only ways we have found to create elements are nuclear processes like radioactivity or fusion. The nuclear processes we have discovered which could create significant amounts of calcium are things that will only occur naturally as part of a nova or supernova. Therefore, by process of elimination, our best theory is that all the calcium we see must have been created by exploding stars.
Which stars exploded to make the calcium we have? How did that calcium get from there to here? How long did that take? We don’t know, not with any certainty. But we don’t know of any other way that our calcium could have been created. Perhaps we will learn of a new way to synthesize elements in the future, and our theory about our calcium coming from supernovae will be challenged. But until then, the supernova origin story, ridiculous as it sounds, is the most likely explanation we have found.
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