Ask Ethan: How many atoms do you share with King Tut?
The answer is larger than you might think, and applies in some shocking ways!
“The beauty of a living thing is not the atoms that go into it, but the way those atoms are put together.” -Carl Sagan
It’s no secret that when it comes to your own identity — the thing that makes you your own unique person — you’re a lot more than just the sum of the atoms that make you up. The food you eat, the water you drink, the air you breathe and everything else your body ingests can be used as raw materials for creating new molecules, new cells and new parts of your body throughout your life. The thing is, they all came from somewhere, and that’s what Brendan Markovich wants to know:
I would like to know what are the odds of the atoms in your body coming from something else in the past? Like a 0.0001% chance that somewhere in your body an atom used to be some part of a Pharaoh in Egypt or a King in England. Can science tell us anything about how atoms are recycled around the Earth and where the atoms in my body may have come from previously?
Not only can science tell you something about this, but it can allow you to estimate a whole slew of interesting facts concerning exactly what makes you up.
First off, let’s disabuse you of any incorrect preconceptions of what “you” actually are. What you think of as “you” is normally things like your bones, muscles, skin and other organs, but from a cellular standpoint, that’s only about 4% of the cells in your body. The other 96%? Split pretty evenly between blood cells and bacteria. Blood cells, most of which are red cells, live for only about 120 days apiece before they’re broken down, excreted, and replaced by new cells made in your bone marrow. Bacteria live everywhere: there are perhaps a million of them on every square inch of your skin, and tens of trillions of bacterial cells in your digestive tract.