Award-winning journalist and economist Tim Harford explains three simple rules for understanding statistics and evaluating truth in the news. Then, you’ll learn about why our microbiomes may have come from dirt.
Award-winning journalist and economist Tim Harford explains three simple rules for understanding statistics and evaluating truth in the news. Then, you’ll learn about why our microbiomes may have come from dirt.
Additional resources from Tim Harford:
Microbes in dental plaque are more like soil microbes than tongue microbes, which suggests our microbiomes came from dirt by Cameron Duke
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/did-your-microbiome-come-from-dirt
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about three simple rules for understanding statistics, from award-winning journalist and economist Tim Harford. Then, you’ll learn about why our microbiomes may have come from dirt.
CODY: Let’s satisfy some curiosity.
If you read the news or open up social media, you'll see a lot of statistics being thrown around. If you're not a statistician, how exactly are you supposed to know whether a given number is accurate, or if it's being distorted to mess with your emotions? Luckily, today's guest has an easy rule of thumb you can use the next time you run into a statistic you're not sure about. Tim Harford is an award-winning journalist, economist, and broadcaster, and author of the new book "The Data Detective: Ten Easy Rules to Make Sense of Statistics." Here's a clip from our conversation.
[CLIP 3:43]
Again, that was Tim Harford, an award-winning journalist, economist, and broadcaster, and author of the new book "The Data Detective: Ten Easy Rules to Make Sense of Statistics." Tim will be back tomorrow to talk about the statistics surrounding the COVID vaccines.
No matter how often you brush your teeth, your mouth will always be full of bacteria. And recently, scientists discovered that these very bacteria have a dirty little secret. They found that bacteria living on your plaque are more similar to bacteria living in dirt than they are to the bacteria living on your tongue. And this may say big things about how the human microbiome evolved.
For microbes, your mouth is full of little microhabitats. Just like natural selection molds species that live in treetops differently than the ones that live on the forest floor, the bacteria that live on your tongue should be different than the bacteria on your teeth. But how different should we expect them to be? I mean, they are neighbors. It’s easy to assume they’re closely related.
Recently, a study carried out by scientists at the University of Chicago Medical Center put that assumption to the test. The scientists focused on the genetic relatedness of a group of microbial species called the Saccharibacteria. They were able to use a technique called metagenomics to organize the species they found into six clades [CLAY-ds], or evolutionary groups. Think of clades as all species that share a particular common ancestor. We would expect them to have a lot of the same DNA. With those clades established, they were able to zoom out a bit and see how each of them compared to each other and to similar clades in other environments, like dirt and the human GI tract.
So here’s where it gets surprising. It turns out that the bacteria that live on the plaque of human teeth are more closely related to species that live in dirt than to other species in the mouth. And the bacteria on the tongue are more closely related to bacteria in the GI tract than to other species in the mouth.
This has powerful implications for the evolution of the human microbiome. The researchers’ hypothesis is that plaque may be an environmental stepping stone for bacteria to enter the human microbiome. These microbes might enter our mouths via dirt on our food or our hands, and the ones that can survive make their homes there. Bacteria from dirt may not be able to survive on the tongue, but if they can survive on plaque and adapt to that environment, then they may have an easier time transitioning to other areas of the body.
So yeah: maybe dental plaque isn’t all bad — it may be one reason we have so many beneficial bugs in our bodies. It’s still a hypothesis that needs to be tested, but as far as origin stories go, I’d say it has some teeth.
Let’s recap the main things we learned today
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CODY: Today’s stories were written by Ashley Hamer and Cameron Duke, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was produced and edited by Cody Gough.
CODY: 9 out of 10 dentists recommend you join us again tomorrow to learn something new in just a few minutes. I’ll let you practice the 3 C’s of calm, context, and curiosity to decide whether that’s really true, or if it’s just a dumb joke.
ASHLEY: And until then, stay curious!