We Are All Related

Hello Vsauce, this is Michael, and you are my family. Scientifically speaking, geneticists tell us that every person on Earth is at least a fiftieth cousin to everyone else on Earth. Must be like this. Think of it like this: he has two biological parents, four biological grandparents, and eight biological great-grandparents. It keeps doubling. Well, if you trace your family tree back to the time of the ancient Romans, 64 generations ago, that tree would need a quintillion separate individuals, which is a number greater than the number of humans who have ever existed. Ever. So what does that mean? Well, I think Bill Bryson said it best when he said, "You couldn't be here without a little incest; actually, quite a bit of incest." Nothing ridiculous, mind you, but if you go back far enough in your family tree, you'll find that, quite often, people who were distant relatives had children.

In fact, if you are currently dating or married to someone who is from your own country and your own ethnicity, there is a one in five chance that the two of you shared a common family member less than 10 generations ago. Additionally, because our society is becoming increasingly mobile, our most recent common ancestor is becoming more recent. Mathematical models now show us that for everyone, for every human being on Earth right now, our most recent common ancestor probably lived only 2,000 to 4,000 years ago. A recent study (it's fantastic, you should read it) found that there was a person alive as early as 300 BC. which is

related

to every person alive on Earth today.

Their study also found that that person probably lived in Taiwan near a busy port city, so his descendants could spread quickly around the world. Now, all that being said, you only get half of your genetic information from your mother and the other half from your father, and as you go up your tree, it's entirely possible that very, very distant ancestors literally did not contribute to your genome. . So, who are you? I've said this before, but because bacteria are much smaller than the average human body cell, your body contains more bacteria than your own cells. And forget about trying to remember every single cell and bacteria in your body.

They are dying and being replaced constantly. Even cells like those in the brain, which seem to live a long time, still absorb new nutrients and expel waste, meaning that about every five years, every atom that used to make up the body has been exchanged. Do you remember what you were like five years ago? Well, the atoms that make up your body, surely not. This is a bit existentially scary, but it leads to a very good question. To begin with, how many atoms are there inside my body? How much are a billion atoms? Well, here's one way to think about it.

If you counted a larger number every second, it would take you 12 days to count to a million, and if you wanted to count to a billion, it would take you 32 years. So a billion is a very big number, but not when it comes to atoms. The atoms are so inconceivably small that even if you had a billion, say, sodium atoms, their total weight would be only 38 femtograms. Each individual cell in your body, too small to be seen even with the naked eye, contains 100 times more atoms than stars in the Milky Way. Multiply that by the number of cells that make up what we call ourselves and each human body contains more atoms than stars in the known universe.

Such large numbers lead to some pretty mind-blowing truths, for example this one mentioned by Bill Bryson: Because our bodies contain so many atoms, and because we recycle them so vigorously, statistically speaking, about a billion atoms inside our body used to belong to Shakespeare. One billion of its atoms belonged to Beethoven. A billion atoms in your body right now, as you sit and watch this, used to be inside Buddha's body. You could also think of it this way: a thousand years from now, when humans first land on a planet outside our solar system, that first person to set foot on the surface of the alien planet, their body will contain a billion atoms that are in you right now.

And as always, thanks for watching.