IRA FLATOW: This is Science Friday. I’m Ira Flatow. How do you find out if there is a secret room hidden in an ancient pyramid? Not the same way you’d discover hidden places in that home you’re remodeling. You just can’t go busting through the walls to find out what’s on the other side, right? So, how do you do it?

Case in point. A group of scientists recently suspected that there might be an undiscovered chamber hidden in the Great Pyramid of Giza. Following up on their hunch, they turned to a technique scientists use to measure the density of volcanoes to try and see if there was anything behind that earth and stone besides, well, more earth and stone. So did they find anything? The suspense is killing me, so let’s find out.

Joining us to discuss this and other short subjects in science Annalee Newitz, tech culture editor at Ars Technica. Welcome back.

ANNALEE NEWITZ: Hey, thanks for having me.

IRA FLATOW: OK, let’s continue this story. So you have this room is hidden. How do they know that?

ANNALEE NEWITZ: So the north side of the Great Pyramid at Giza has this characteristic architectural feature that suggests that somebody might have wanted to hold up a ceiling behind the outer wall of the pyramid. So scientists thought, well, maybe there’s something behind. Maybe there’s a chamber behind there.

The problem is, as you said, you can’t just dig it up or break into it. So what they did was they used a technique called muography. Not photography. Muography works with subatomic particles called muons that are created through collisions in the upper atmosphere and they rain down on Earth at a very regular rate. And the thing that’s great about muons is they can pass through incredibly dense amounts of earth and stone, but they sometimes get absorbed the denser it gets.

And so if you go into one of the lower areas of the Great Pyramid, there’s a few corridors in there that we’ve opened up. They went into a corridor under the area where they thought there was this possible chamber and set up plates that capture muons and left them there for three months and went back to see basically the absorption patterns of those muons to see how many were absorbed and how many got through and if there was a pattern. And they found there was a pattern that looks like there may be a void space somewhere in the pyramid right behind that architectural feature.

IRA FLATOW: So they saw a shadow, like you would see on an X-ray instead of muons coming where X-rays would be coming in.

ANNALEE NEWITZ: That’s right. So you’re using muons instead of X-rays, and they’re just coming down from the atmosphere.

IRA FLATOW: Just to make sure that we say no cows were harmed in this experiment.

ANNALEE NEWITZ: That’s right.

IRA FLATOW: So what do they do now? They know it’s there and they can’t get in, can they?

ANNALEE NEWITZ: So right now the group, which is called The Scan Pyramids Mission, is hoping to get another year to do more research to basically do more muography. Because they want to make sure that what they’re seeing is actually some kind of chamber instead of just the muons picking up spaces between the stones. It’s possible that there’s larger stones and smaller stones that have gaps between them.

So they don’t want to do anything to harm this wonder of the world until they really are certain that there’s something there. So first another year of gathering, and then they’ll see what they’re going to do next.

IRA FLATOW: I think there’s a song here somewhere about gathering muons, but let’s move on to your next story that’s out of Brazil about some monkeys that were spotted banging rocks together. I don’t get it. What’s so special about that?

ANNALEE NEWITZ: So these are Capuchin monkeys, the very cute monkeys, that were spotted by some researchers in a Brazilian national park. And they’re banging rocks together. So they’re using rocks as tools, which is great. They’re using one rock is a hammer and they’re exhibiting this odd behavior where they smash the rocks together and then lick the rocks.

So we’re not sure why they’re doing that, but an even bigger mystery is the fact that in banging the rocks together they were able to produce what are called flake tools. They’re basically just flakes of rock, but they look exactly like the kinds of tools that our early hominid ancestors used over 3 million years ago when they were first developing sharp tools for cutting and scraping.

So basically what these monkeys have done is something that scientists didn’t think that any other species could do, which is by banging two rocks together they’ve created a third kind of rock that would be an ideal tool.

IRA FLATOW: We don’t know if they actually use them as tools. We just know they made the rocks, right?

ANNALEE NEWITZ: In fact we know for sure they’re not using them as tools. So this is not a story about monkeys suddenly learning to use knives, which would be a little bit terrifying. But what they’re doing is because they’re creating these flake tools– they’re not tools there they’re rock flakes that look like tools– what it tells us is that there wasn’t something special about our ancestors that they could create that kind of rock shape.

It has been believed and been proposed that part of the way that humans evolved to use tools was that some human at some point, some early hominid, had this great idea, if I bang two rocks together, I can create a kind of a sharp knife-like tool. Well, that’s not the case, because now we know that monkeys can accidentally create these knife-like tools by banging rocks together.

So the missing link in terms of how humans had that brilliant idea to start using sharpened stones as knives, it must have come later. Maybe they were accidentally creating these kinds of flakes and then decided, let’s use them to cut some meat up.

IRA FLATOW: Finally we have something new that we’ve learned about the culture of sperm whales. Fill us in on that.

ANNALEE NEWITZ: Yeah, I love this story. So one of the things that I think the public may not be aware of is that a lot of marine biologists who study whales, sperm whales and other whales, widely accept that sperm whales create cultures. They create clans where they speak distinctive dialects. They communicate in a series of clicks. And each of the clans, actually scientists name them after the characteristic clicks that they use to identify each other and to communicate underwater.

And so some of the groups are called things like “regular” and “short” just to describe the clicks they use, different clans. And so what recently a group of scientists found is that not only do these clans speak the same language, but they actually move together. So if they decide to leave an area, they all leave at once.

And there were these two clans off the coast of the Galapagos Islands that used to hang out all the time in the 80s and 90s, and then they just disappeared, and there were no whales there for a very long time. And then a few years ago two new clans came into the area. So basically what we’re seeing here is kind of like neighborhood turnover. Basically, this neighborhood had had these two clans, they left, and two totally new groups moved in and took over the food chain there and started acting like sperm whales.

IRA FLATOW: Whale gentrification going on right there in the neighborhood.

ANNALEE NEWITZ: It could be whale gentrification, yeah. Or just could be new immigrants to the area setting up shop.

IRA FLATOW: There you go. Thank you. Thank you, Annalee. Always good to have you. Annalee Newitz is a tech culture editor for Ars Technica.

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