What is a Gut?
What is American Gut?
What is 16S rRNA?
Do you really have a robot?”
The robots enable the scientists to rapidly extract the DNA from thousands of samples simultaneously. Specifically, they can load your samples into small plastic plates each with 96 little wells. The robot then loads chemicals into the wells and heats the chemically-laced wells enough to break open the bacterial cells in the sample, BAM! This releases the cell’s DNA. The robots later decode the specific letters (nucleotides) of the 16S gene using the nucleotides dumped out of the broken microbial cells into these plates.
Tree of life
What is a microbiome?
What do my microbes eat?
Where do my microbes come from?
What will we discover in your gut?
Nucleotides are those hunks of which DNA and RNA are made. They come in different forms to which scientists have assigned names and letters. When the robots are done with the work, what they produce are lists of strings of nucleotides (called genetic barcodes) in all of 16S rRNA genes from all of the cells in your sample. These strings of nucleotides tell the scientists which kinds of life are in your sample (and in you). But because we will only have samples of little stretches of the 16S rRNA genes, we won’t know exactly which species are in you, just which lineages they are from. You might have the bacterial equivalent of a chimpanzee and a gorilla in you, but all we’ll know from your sample is that there was an ape. Knowing you have a bacterial ape in your gut will, on its own, not tell you so much. The real information will come from context, statistical context. I know, that sounds boring, but I promise it is not.
We think that hundreds of different things you do during your life, in addition to what your mother and father did (let’s try not to think about that), your genes and even just where you grew up influence which species of microbes are found inside you. But we don’t really know. The problem is humans are so darn complicated. What we need to be able to do is to compare large numbers of people, people who differ in many ways, to be able to sort out which variables are sometimes a little important and which ones are the big deal. Is a vegan gut very different from a vegetarian one? Does eating yogurt make a big difference? Do the effects of a C-section birth last forever? These questions require us to compare many people, which is where you come in. Your sample, gives us context and it gives you context too. It won’t be terribly exciting on its own (you will know which ancient lineages you have dividing and thriving inside you. OK, that is pretty cool on second thought), but it will be very exciting in context. Where do you fall relative to fish eaters, sick people healthy people, hunter-gatherers, or even your dog? You will know and we will know. And this is not all.
All of the questions I have mentioned so far are what I might call first order questions. How does this thing compare to that thing. But what we’d love to be able to answer are second order questions, contingent questions, questions such as whether the effect of your diet depends on your ethnicity (it probably does), whether the effect of having a dog depends on whether or not you live in the city (again, I bet it does) and so on. These questions are exactly the sort of question we have failed to be able to answer well when it comes to diet, because we don’t have big enough samples sizes. We can see the forest for all of humans. Well, that isn’t quite right, but you get the idea, we will be able to understand elaborate effects of multiple variables on the wilderness between your pie hole and the other hole and that, to us, is exciting.
A few of the stories of the evolutionary tree in your gut
Further reading from Rob Dunn
Rob Dunn is the founder of the Wild Life of your Homes Project and the author of “The Wild Life of Our Bodies.”