Short Wave - The problem with modern avocados — and the ancient solution

Episode Date: July 24, 2026

Did you know that when you pick up avocados at the supermarket, make avocado toast at home or order guacamole in your burrito, you’re probably consuming only one genetic type of avocado? Yep, it’s the Hass avocado. Since it originated in California in the 20th century, it’s been grafted onto trees worldwide. And today, it makes up more than 80 percent of commercial avocado production. Its bounty is a double-edged sword: It makes our avocados consistent; it also makes them susceptible to threats like new diseases and climate problems. In other words, we’re putting all of our eggs – er, avocados – in one basket. This episode, we get the inside scoop on new research that could help shore up the avocado’s chances at a long, more genetically diverse future. That way, avocados and their lovers alike can continue to thrive in the future.Read the research paper here.Interested in more plant anthropology science? Email us your question at [e-mail] public media with NPR+ and enjoy perks for over 25 podcasts like this one. It includes perks like bonus episodes, early access, archive access, curated playlists and sponsor-free listening. Learn more at plus.npr.org. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

Hey, Nate Rod here. Before we get into this episode, a quick ask for you to lift that finger and press the follow button on your app. We love telling you all the latest cool science out there. And following us helps you make sure that you never miss any new science stories coming from us. And have smarter, more informed conversations with all of your friends. We all want that, right? Okay, PSA over. Here's the show. You're listening to Shortwave from NPR. Hey, shortwavers, I'm still Nate Rot. And I'm Hannah Chin. With our biweekly science news roundup featuring the one, the only, the exquisite.

Elsa Chang, of all things considered. Nate Rod, you're very exquisite, too. Thank you so much for having me again, guys. Happy you're here. Okay, so this week we've got a few discoveries that help us better understand this wacky world that we're all living in. The first is a discovery about ancient avocados, which are my favorite kind to eat. that could help us keep slathering our chips with guacamole today. And the next one looks at the mummified remains of Egyptian princesses.

And upends some of our assumptions about how they lived. And the last study takes a global look at Birdsong. Trust me, Hannah and Elsa, it's going to be trilling. Get it? Yeah. All puns considered. You're listening to Shortwave, the science podcast from NPR. All right, Hannah and Elsa, we've got a lot to get into.

Let's start with ancient avocados. Is my avocado toast in danger here? Well, not yet. So when you pick up avocados at the grocery store or when you get guac and your burrito, chances are that it's from a single type of avocado. It's called the Haas avocado. Right. And Elsa, this type of avocado makes up more than 80% of commercial avocado production.

Which is, you know, kind of convenient because it means that our avocados tend to be, like, consistent in their size, shape, flavor-wise. But because they're all genetically identical, they're all susceptible. to diseases in the exact same way. Oh, like farmers are putting all their eggs, or avocados, shall we say, in one basket here? So are there other varieties of avocados that we could grow so there's sort of like genetic variation?

Yeah, there are. And a lot of them look very different. They're bigger, they're whiter, they're glossier, less bumpy, usually like lighter, green, sometimes come in different shapes and sizes. And on the inside, they tend to be less fatty. So this is archaeobotanist, Kevin Wan. He's a fellow at the Smithsonian National Museum of Natural History and a Ph.D. candidate at Texas A&M doing avocado research, even though up until a couple years ago, he'd never tasted one.

I was going to see if I could go my entire PhD studying avocados without ever having eaten one or eaten guacamole. But what Kevin wanted to know was how much genetic diversity he was dealing with. So he collected DNA samples from a bunch of different avocado varieties in Mexico and Central America, mostly from local farmers or home gardens. Yeah, and he sequenced the genomes of these avocados to compare them to each other and also to an existing archive of avocado varieties. Kind of like a 23-in-me or Ancestry.com test, but for avocados. That's kind of cute. Okay, so what did they find? So he found a lot of genetic diversity and a few varieties of Nicaraguan avocados that were super genetically similar to those in South America,

which suggests they were brought there by ancient farmers and then hybridized with native species. Kevin published a paper on these findings this past week in the scientific journal Plants People Planet. And I talked to anthropologist Amber VanderWarker. She's at UC Santa Barbara, and she wasn't involved with the study. But she said Kevin's research really reveals this genetic diversity that has been preserved over the past thousands of years by these intrepid ancient farmers. And she told me it's important for us to keep this diversity alive, right? So avocados stay sustainable into the future. Totally. But I am still dying to know did Kevin ever eat. an avocado. He did. When I was interviewing that farmer in Nicaragua, he picked off one of the

avocado foods and said, here, try this. And I couldn't say no. No, you couldn't. Exactly. And Elsa, you'll be happy to know that Kevin told me he eats avocados and guacamole almost every single day now. Good for him. Good man. So let's move on to Egyptian princesses. Tell me more. Yeah. So maybe what I love most about the story is that it came from an effort to unclutter a basement. Yeah, so that's what the Egyptian Museum in Cairo was doing. When they rediscovered this box with the mummified remains of six members of an ancient Egyptian royal family that had been excavated and stashed more than 100 years ago.

Yeah, a totally normal thing to find in one's basement. Of course. So who was this family? It was five princesses and a king who lived thousands of years ago around 1800 BC. Wow, a girl dad. Yeah, exactly. Yeah, but one of the things that confused the archaeologists when they found these remains was that the women were all buried with weapons like daggers and maces and bows and arrows, which archaeologists typically associate with men. Of course.

So the assumption was the princesses were buried with these weapons for symbolic reasons. Symbolic? Wait, hello. Have these people not ever heard of Xena warrior princess? Because women do carry weapons sometimes, okay? Exactly. And that's what the person who helped find these remains wanted to figure out. Yeah, her name is Zinab Hashish.

She's a bioarchologist at Benny Sweff University in Egypt. And she says, you know, we all have this assumption that princesses are like Disney characters. That they are fluffy. They are wearing beautiful dresses and very beautiful jewelry. When Zainab looked at these bones, she noticed that these skeletons had really strong muscle attachments. These women were buff. Exactly. And she did a deeper analysis of the bones.

and she found these women were, yeah, buff. They were really strong. Strong for arms and shoulder. And also, for example, Princess Nobhotib, her right second hand bone shows a unique curve. And that curve, Elsa, likely came from the repeated use of a bow and arrow. Wow. Wait, so these women literally were warrior princesses? Well, Zinab says it's unclear if these findings, which are published in the journal Frontiers and Environment are archaeology, proved that they were actually like warriors in the sense that they fought.

That's also what I heard from another Egyptologist who wasn't involved in this study. But he says it does show that their lives weren't as relaxed as we might have thought that they did real work. They were shooting bows and arrows. All right. Our final topic is birdsong. What are you going to tell me about singing birds? Yeah, so this study analyzed more than 116,000 bird songs from perching birds, which include, you know, robins and thrushes, warblers, and crows, and on and on. Cool.

Okay. So what were the scientists looking for specifically? specifically in all of these bird songs. Yeah, so they were listening for how the pitch of songs were changing over time to try to find patterns. Acoustic motifs is the technical term. And they found that for all the variety there is in these birds worldwide, they're all trying to communicate basically one of two messages, either attracting mates or claiming territory. And they use these eight basic motifs. Okay, so what are the eight different motifs?

So there are three different types of trills. There is a slow trill sung here by a northern cardinal. recorded outside of Minneapolis. And an ultra-fast trail. Whoa. Was that the ultra-fast I just heard? Ultra-fast. Yeah, and that one's sung by a bohemian waxwing

in the Canadian province of Newfoundland and Labrador. That's amazing. It was almost like, I don't know, like a drill. The most appropriate use of the word ultra, you can imagine. Yeah, and it's worth noting that all these recordings were collected from a public database where Borders uploaded songs. And we don't have time. to cover all eight of them.

But another pattern that's maybe worth knowing is the flat whistle. That's sung by a three-waddle bellbird in Costa Rica. And the reason it's worth knowing that call is the researchers on this new study found that in the dense, loud, tropical forests all over the world. Birds have independently evolved this type of call. So that flat whistle call, does that give them some kind of advantage? Well, it's simple and it's loud. So it can be heard in a wide area. Here's the lead author of this study, Quentin Bequelli.

He's a PhD candidate sitting by acoustics in Paris. So that's really impressive to see that nature found the same solutions, for the same constraints, but across different parts of the world. So in other words, Elsa, birds separated by oceans and continents all landed independently on the same types of acoustic patterns to communicate. That is so cool! Well, Elsa, thank you so much for geeking out with us this week. Come back anytime. Oh, always. It's so fun to hang with you guys.

You can hear more of Elsa Chang on Consider This NPR's Afternoon podcast about what the news means for you. And for more science stories, just like this one, follow Shortwave on whatever app you're listening to. This episode was produced by Burley McCoy and Jordan Marie Smith. It was edited by Lauren Gonzalez, Rebecca Ramirez, and Christopher Intaliata. Tyler Jones, check the facts. Anli Wong, Robert Rodriguez, and Peter Alana were the audio engineers.

I'm Hannah Chin. And I'm Nate Rot. Thanks for listening to Shortwave, the science podcast, from NPR.