JOHN DANKOSKY: This is Science Friday. I’m John Dankosky. Ira Flatow is away.

In the search for new antibiotics to counter the growing problem of drug resistant infections, no stone goes unturned. And that includes the human body itself. Scientists are looking at our own microbes for inspiration, with the idea that they may have developed some helpful weapons in their war to coexist with the rest of a gut, skin, and other flora.

The latest promising find? Well, it’s right under, or inside, our noses. Here with that story and other short topics in science is my guest, Ed Yong. He’s a science writer for The Atlantic. Normally he’s in London, but this week he joins us from Washington DC. Welcome, Ed.

ED YONG: Hi, good to be here.

JOHN DANKOSKY: So first of all, why go digging around for antibiotics in the nose?

ED YONG: So a lot of our antibodies come from bacteria in the world around us, and especially in the soil. But the human microbiome– the bacteria that live in our bodies– are a largely untapped source of antibiotics, but they are a potentially valuable one. Our bodies are home to so many different microbes, which are all competing and cooperating with each other, and they have weapons to fight off their rivals.

And those weapons might be especially potent in the nose, because unlike, say, the gut or the mouth, the nose is a bit of a nutritional wasteland. It isn’t continually washed with food, so the microbes there must be very competitive in order to soak up the meager resources.

JOHN DANKOSKY: So what do they find in the nose?

ED YONG: So they found that a species of bacterium called Staph lugdunensis, which is found in about 10% of us, makes a chemical called lugdunin, which can kill Staph aureus– the bacterial species that, in its antibiotic resistant form, is better known as MRSA, or “mersa.”

So this is great. It’s a new potential antibiotic that can treat a bacterium which causes some potentially nasty infections, and is starting to shrug off a lot of our existing antibiotics. And it comes at a time when no new classes of antibiotics have reached the market for many decades.

And even if this promising lead fizzles out, this approach of mining the human microbiome for potential new drugs is, I think, a very sound one. And this study proves that it’s a worthy place in which to look.

JOHN DANKOSKY: Very interesting. So let’s move on. Tell us who, or what exactly, is a LUCA?

ED YONG: Right. So LUCA stands for the Last Universal Common Ancestor. So that is the organism that gave rise to everything that’s currently alive on earth. Every microbe, every animal, plant and fungus, descends from LUCA. It’s our great, great, great, great, great, great, great, great, great, great, great, et cetera, grandparent.

And, you know, what LUCA was is an open question. But one way of finding out is to take modern organisms and look at their genes and to try and find those that likely date back to LUCA, so genes that are shared throughout the tree of life. And when a group led by Bill Martin did this, they came up with a list of 300 plus genes and these paint an interesting portrait of what LUCA was like.

So it likely was a microbe that thrived in hot temperatures. It subsisted on hydrogen for energy, and it shunned oxygen so it was anaerobic. And that means it probably lived in an environment like a hydrothermal vent, like one of these undersea vents that is belching out hydrogen gasses that are there really, really hot. There no oxygen there. It’s a very primordial hadean of worlds. But it’s a likely scenario for where the ancestor of all living things arose.

JOHN DANKOSKY: Interesting. I want to move on to a really cool interesting living thing. Tell me about this. If I were in Mozambique and I wanted to get some help finding a little bit of honey, what would I do to summon somebody to help me?

ED YONG: Right, so what you want is the greater honeyguide, a bird that is known for leading people to sources of honey and that gets exposed bits of beeswax in return. And the Yao people of Mozambique have this special signal, which I’m now going to do a terrible impression.

JOHN DANKOSKY: I can’t wait.

ED YONG: It goes like this. Brrr-hmm. So you say brrrr, you roll the R’s, and you go hmm, as if like you’re asking a question, but you’re a little bit irritated at the same time.

And that call summons the bird. It’s a call that’s only ever used for this purpose. The bird seems to understand it and it responds by flying in the direction of a bees’ nest, leading the people there. The people smoke the bees out with fire and they get the honey and the bird gets some of the remnants.

So it’s this beautifully mutualistic relationship between people and a wild animal, and it’s one of the few examples where wild, untrained animal attaching a meaning to a human signal, and then responding appropriately.

JOHN DANKOSKY: Again, the birds need us because they can’t really deal with the bees and get inside there themselves, they need us to smoke them out and help get inside.

ED YONG: Yeah, that’s right. And there are some cases where greater honeyguides have been found stung to death by bees. So without human help, they wouldn’t be able to get access to the wax that they so love to eat. So they depend on us as much as we depend on them.

Now the interesting thing is that relationship sort of breaks down in some parts of Africa where certain groups of people actually try and bury honeycombs and sort of stop the bird from gorging itself, presumably because keeping it hungry makes a more motivated guide. So that’s an open question now, like how does that relationship vary from mutualism to manipulation in different parts of the continent?

JOHN DANKOSKY: There’s also a new theory about the origin of one of our oldest and most persistent diseases, tuberculosis– something you’ve written about. Where did this come from?

ED YONG: Yes, tuberculosis has been with us for thousands of years. Today it still kills more people than any infectious disease, about 1.5 million people. So its interesting thing where it comes from. And originally people thought maybe we got the bacterium that causes it from animals, and actually it seems that it’s probably the other way around.

So that mycobacterium tuberculosis was probably originated from a soil-dwelling microbe, it jumped into humans, and then we gave it to the rest of the animal kingdom.

So what was the thing that made it start colonizing our bodies and spread from host host? Well, a couple of Australian scientists think that fire was a possible answer, because fire does two things. First, it produces smoke and smoke damages our lungs and our airways and creates conditions that make it easier for an opportunistic environmental microbe to colonize.

And then fire also gathers people in dense places. People huddle for warmth around fires, and that creates an evolutionary pressure for that opportunistic bacterium to become better at jumping from one host to another.

So fire created the conditions in which an environmental microbe could have taken up shop in our airways, and then gained the ability to spread to new people.

JOHN DANKOSKY: Well that’s the news roundup for this week. Thanks again to my guest, Ed Yong, a science writer for The Atlantic. Thanks so much, Ed.

ED YONG: Thanks for having me.

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