IRA FLATOW: This is Science Friday. I’m Ira Flatow. This week, amidst the swirling muck of this election campaign, President Obama gave a shout out to science.

PRESIDENT OBAMA: I’m a science geek. I’m a nerd. And I don’t make any apologies for it.

[APPLAUSE]

I don’t make any apologies for it. It’s cool stuff.

IRA FLATOW: He was speaking at the White House Frontiers Conference in Pittsburgh. In attendance was my next guest, a proud science journalist. Don’t know if she’s a geek. We’ll ask her. Nadia Drake, she’s a science writer with National Geographic and she joins us from WESA in Pittsburgh. Welcome back.

NADIA DRAKE: Hi, Ira. Thank you for having me. And I am definitely a geek.

[LAUGHTER]

IRA FLATOW: That’s two in the room now.

NADIA DRAKE: Exactly.

IRA FLATOW: You were at this conference and you saw the President speak. Was there any news, or mainly just a feel good event?

NADIA DRAKE: Well, it was mostly an event that was attended by a number of scientists and policy makers and innovators who were getting together to consider the future of various topics, including things like interplanetary exploration, and personalized medicine, artificial intelligence, smart cities and smart transportation, and climate change.

IRA FLATOW: Yeah, a lot of interesting things for the future– for any next president to tackle.

NADIA DRAKE: Absolutely.

IRA FLATOW: Elsewhere this week, there’s a story about a virus lifting some genes from the black widow spider?

NADIA DRAKE: Hmm-mm.

[INTERPOSING VOICES]

IRA FLATOW: –about that.

NADIA DRAKE: So, I think it’s easiest to consider this story as kind of like the biological version of Russian nesting dolls. You know where smaller and smaller and smaller dolls are tucked into one another. That’s a useful framework for thinking about what I’m going to tell you next.

Which is that in this case we’re not dealing with dolls but with a virus that tucks itself inside a type of bacteria that tucks itself into spiders and insects. The virus is called WO. And that’s spelled capital W, capital O, like whoa.

IRA FLATOW: Whoa.

NADIA DRAKE: And whoa! Exactly.

[LAUGHS]

And it infects a bacteria called Wolbachia, which in turn is found inside animals, such as insects and spiders. Now what’s interesting is that the virus’ genome contains some snippets of animal genes, including those that produce venom in black widow spiders. In fact, one third of its genome is basically a hodgepodge of various animal genes. And that’s something that scientists did not think could happen. So–

IRA FLATOW: Wow, so over the life evolution of this virus, it went around picking up genes–

[NADIA LAUGHS]

–from things it infected.

NADIA DRAKE: Yes, so that’s one of the questions that scientists are trying to answer is, how exactly did a spider gene end up in the viral genome? Because normally you only see viruses grabbing genes from the organisms that they actually infect. Which in this case is not the spider or the insects, but the bacteria that lives inside them.

So viruses that infect bacteria normally only steal bacterial genes. Viruses that infect animals like spiders and insects will steal genes from the spiders and insects. But this is the first time that virologists have seen animal-like DNA tucked into a viral genome that normally only infects bacteria.

IRA FLATOW: Boy, the mind can go wild with this. I mean let’s move onto the next story. There’s news from your home, National Geo, this week– right– about some ancient footprints.

NADIA DRAKE: That’s right. Yeah, so in northern Tanzania near Arusha there’s a volcano that the Maasai call the Mountain of God. And near that volcano is a mud flat the size of a tennis court that is crisscrossed by more than 400 prehistoric human footprints that could be as many as 19,000 years old. It’s the largest such assemblage of ancient human footprints found in Africa.

And scientists think that all of those footprints were laid down over a period of hours to days. Some of them show people jogging, keeping upwards of a 12 minute per mile pace. Others show groups of maybe a dozen people, mostly women and children, walking together. And there’s a track that looks like it was made by a person who might have had a broken toe.

IRA FLATOW: They can get that granular with it? Wow.

NADIA DRAKE: Yeah, it’s really interesting.

IRA FLATOW: Where was it found? In Tanzania I understand?

NADIA DRAKE: Right. In northern Tanzania near the Kenyan border.

IRA FLATOW: Yeah, well we know where the fertile ground Tanzania is [INAUDIBLE] by [INAUDIBLE] and all that kind of stuff there.

NADIA DRAKE: Oh, it’s beautiful.

IRA FLATOW: Yeah. Let’s go to space. Now the moon may be more liable to craters than we thought. Is that what you’re hearing?

NADIA DRAKE: Yeah, so it seems kind of obvious that the moon is constantly being pummeled, so craters are one of its most distinctive features. But it’s the rate at which these craters appeared recently that surprised scientists.

So a group of scientists studied images that were taken by NASA’s lunar reconnaissance orbiter, which has been orbiting the moon since 2009. And what they found after scanning through more than 14,000 before and after images taken of the same sites were 222 new impact craters all made over the last seven years. And that’s 33% more craters than were expected for those that are at least 10 meters across. So something that a school bus could fit into, for example.

IRA FLATOW: So is there worry then if we went back to the moon that, you know, we might get hit by something that’s making more craters, because there are more craters than we thought?

NADIA DRAKE: Right.

[LAUGHS]

So what’s concerning here in terms of a moon base, for example, is that the cratering rate is a lot higher than what we had expected. So that means that any future lunar base, which is a really fun thing to think about, would need to be somewhat more fortified against these collisions from outer space. Because there are more of them happening at you know– and faster than we expected.

IRA FLATOW: Well, that would be pretty strong fortification for something incoming like that.

NADIA DRAKE: Right.

IRA FLATOW: Finally, some other astronomy research. But it’s probably not aliens, but looks like something might be?

NADIA DRAKE: Some day it will be aliens, but–

IRA FLATOW: Maybe not.

NADIA DRAKE: Today is not that day.

IRA FLATOW: What are we talking about here?

NADIA DRAKE: So scientists were looking through some spectra taken of stars in the Sloan Digital Sky Survey, and they found 243 stars. The Specter of which contained a periodicity that could be mimicking what we might expect to find from an extraterrestrial civilization. It is extremely unlikely that periodicity is being caused by aliens, but it’s more likely that it’s an artifact of the instrument itself.

IRA FLATOW: Oh, that’s measuring it. Huh?

NADIA DRAKE: Right, exactly.

IRA FLATOW: So the star is sort of blinking at a certain rate that you might think is sending us Morse code signals or something like that.

NADIA DRAKE: Yeah, so basically. It’s a little more complicated but, yeah. There’s something that someday could be alien Morse code.

IRA FLATOW: Takes a little more, as Sagan used to say, a little more evidence than extraordinary evidence needed for–

NADIA DRAKE: Yes, extraordinary claims require extraordinary evidence.

IRA FLATOW: Thank you, Nadia. It’s great stuff.

NADIA DRAKE: Yeah, thank you.

IRA FLATOW: Nadia Drake, science writer with National Geographic.

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