MARY LOUISE KELLY, HOST:
It is time for our science news roundup from Short Wave. That is NPR's science podcast. I am joined by two members of the team, Angela Zhang and Emily Kwong. Hi, you two.
EMILY KWONG, BYLINE: Hi, Mary Louise.
ANGELA ZHANG, BYLINE: Hello. Great to be here.
KELLY: Hi. So y'all have, as you always do, kindly brought us three science stories that caught your attention this week. What are they?
ZHANG: Well, the first is how air pollution might be making your memory worse.
KWONG: The second is the discovery of an ancient whale graveyard.
ZHANG: And finally, what prehistoric mysteries are revealed by ancient squirrel poop.
KELLY: Ancient (laughter).
KWONG: A time capsule. You'll...
KELLY: Wow. We have a lot of ancient animals going here. Let's start with the serious one - air pollution and memory?
ZHANG: So the study I have for you today is about these really, really tiny particles of air pollution, like 30 times smaller than the width of a human hair. And these particles are released by wildfires and car exhaust among other things, and they're bad for your heart and your lungs, and they can also get directly to the brain through the blood.
KELLY: That sounds awful. What do we know about how they affect, say, a person's memory, though?
KWONG: Yeah, so to study how air pollution affects the brain, researchers used a database containing information about Black Americans living in California. The researchers looked at how much air pollution someone may have experienced based on their home address and then looked at their cognitive test scores. And while we know pollution is bad for the brain in general, what the researchers found is that it also affected a specific type of memory.
KATHRYN CONLON: The people who had been exposed to more pollution over the years had weaker semantic memory. So really, that long-term pollution looked like it was aging the brain's memory ahead of schedule.
ZHANG: That's Kathryn Conlon, a study author. She's a professor of epidemiology at the University of California, Davis. She told me that semantic memory is how your brain stores information, so like that New Delhi is the capital of India or that three plus two equals five.
CONLON: When that's affected, we can think about how that's the kind of thing that might chip away at a person's independence or ability to have the quality of life that we would hope to have.
KELLY: But how do they know it's air pollution and not some other factor in these people's lives?
KWONG: The researchers did control for differences in education and income. But when it comes to geography, you're right - it is hard to separate air pollution from things like noise exposure, which could also influence brain health. They can't say for sure that it's air pollution that is leading to worse memory.
ZHANG: But including Black Americans in research, which is what the study did, means that solutions can hopefully reduce inequity, since they're almost twice as likely as white Americans to have dementia and they're more likely to live in polluted or redline neighborhoods.
KELLY: OK, let's turn to topic Number 2. From up in the air to under the sea, we are going to a whale graveyard. I'm trying to picture this, Emily.
KWONG: Yeah, it's a really cool place. So when whales die, many fall to the bottom of the sea, and when they land, their carcasses become an energy-rich habitat, drawing a wide variety of organisms from across the deep sea to feast. Scientists call these sites whale falls.
KELLY: Whale falls because they're fallen whales. So...
KWONG: Yes.
KELLY: Now I'm picturing, like, a deep-sea buffet for all these (laughter) way deep-down creatures.
KWONG: Yeah, who are used to just getting, like, snacks drifting down to the bottom. So it's really cool. And a research team in China may have found the deepest and most extensive whale graveyard in the world, located in the Diamantina zone in the Indian Ocean. The team published these findings in the journal Nature.
KELLY: And what does this whale graveyard actually look like?
ZHANG: Yeah, so you can picture a nearly 750-mile long stretch of whale fossils. These are bones that are shaped like chimneys or even giant cigars. And the oldest fossils were 5.3 million years old. It's pretty old.
KWONG: So old. And during dives with a submersible, the team also discovered five of those whale falls, these five whale carcasses teeming with scavengers. The team saw a whole thicket of microbes, squat lobsters, brittle stars and jellyfish and even species that may be new to science, like bone-eating worms.
KELLY: Bone-eating worms. OK, Emily, you just said this is the Indian Ocean that we're in, right? Is there something specific about that, Angela, that so many whale carcasses end up in the - this particular part of the Indian Ocean?
ZHANG: One reason offered by the lead author Xiaotong Peng, based at the Chinese Academy of Sciences, may have to do with the shape of the sea floor in this part of the world or maybe even the currents that are around it.
XIAOTONG PENG: The surface currents and the deep currents can funnel or concentrate those carcass on the sea floor.
KWONG: Biologists, by the way, are so excited about this finding because these ecosystems are incredibly unique. Stephen Godfrey, a paleontologist at the Calvert Marine Museum, who was not a part of the paper, said the study reminded him of a trailer for the first in a series of epic movies and that he hopes there will be many more of these blockbusters to come.
KELLY: Hear, hear. OK, that brings us to our last story. You mentioned prehistoric mysteries. You mentioned ancient squirrel poop.
ZHANG: (Laughter).
KELLY: Where is this...
KWONG: We got the goods.
KELLY: Where is this going, Angela?
ZHANG: All right, so we got to go back in time to the Pleistocene Epoch. This is one of the most critical turning points in Earth's history because starting around 12,000 years ago, Earth went from chaotic cycles - so ice, warm spells, back to ice - to the Holocene, which is our current epoch.
KWONG: And a study out this week in Nature Communications zooms in on the Yukon in northwestern Canada, where we find an unassuming critter, the Arctic ground squirrel. The study's lead author, Tyler Murchie refers to them this way.
TYLER MURCHIE: They're kind of like accidental ice age archivists.
KELLY: Archivists? Why archivists?
KWONG: Because they hibernate underground for about eight months of the year, and when hibernation ends, those squirrels are hungry.
MIKKEL WINTHER PEDERSEN: And just wake up like a zombie crawling out of the ground, you know, and finding anything they could eat in the landscape.
ZHANG: That's ancient DNA researcher Mikkel Winther Pedersen. And what an image, right? He didn't work on this paper, but he says squirrels would have eaten really anything - plants, insects and even the remains of animals bigger than them, so archiving their DNA, if you will.
KWONG: In their waste.
ZHANG: In their waste.
KWONG: That's the archiving. Yeah.
ZHANG: (Laughter) And sure enough, you know, they found these groups of plants, but then they also found DNA from woolly mammoths, an extinct form of bison, caribou, an extinct Yukon horse and then even some birds, all, if you can believe it, in these squirrel droppings.
KWONG: (Laughter).
KELLY: That is crazy. So we can study the DNA of woolly mammoths because of this ancient squirrel poop? I had no idea you could learn all that from animal droppings.
KWONG: That's exactly right.
ZHANG: I know. And funny you should say that because in the past, researchers have sometimes dismissed animal excrement because they thought, well, it's only just going to show that animal's DNA, right?
KWONG: But the fact that they learned so much about the environment at this time shows this could be a method for understanding Earth's history. Here's Tyler.
MURCHIE: So if you're out for a hike and you see, you know, some old poop, you might think that it's nothing. But the kind of data you can get is just remarkable. With millions and millions of DNA fragments of all these organisms together, that can paint a picture from something that you otherwise would have just thought nothing of in passing by.
KELLY: OK, mind officially blown. What a way to land us. Angela Zhang, Emily Kwong, thanks, you two.
KWONG: Thank you.
ZHANG: Thanks so much.
KELLY: They work for NPR's science podcast Short Wave, which you can follow for new discoveries and answers to everyday mysteries just like these.
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