The problem with modern avocados — and the ancient solution

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 https://www.npr.org/2006/07/19/5563805/whats-in-a-name-the-avocado-story in the 20th century, it’s been grafted onto trees worldwide. And today, it makes up more than 80 percent https://www.sciencedirect.com/science/article/abs/pii/S026121941730220X?via%3Dihub 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 https://nph.onlinelibrary.wiley.com/doi/10.1002/ppp3.70236. Interested in more plant anthropology science? Email us your question at [email protected] mailto:[email protected]. Support 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 http://plus.npr.org. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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  You're listening to Short Wave from NPR.

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  Hey, Short Wavers. I'm still Nate Rot.

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  And I'm Hannah Chen.

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  With our biweekly science news roundup, featuring the one, the only, the exquisite Elsa Chang, of all things considered.

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  Nate Rot, you're very exquisite, too. Thank you so much for having me again, guys.

• 0:57Speaker 01

  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.

• 1:13Speaker 02

  And the next one looks at the mummified remains of Egyptian princesses and upends some of our assumptions about how they lived.

• 1:20Speaker 01

  And the last study takes a global look at birdsong. Trust me, Hannah and Elsa, it's going to be trilling.

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  Get it?

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  This message comes from Planet Visionaries, the podcast celebrating the people creating practical, hopeful solutions for the planet's urgent conservation challenges. Hosted by legendary climber and advocate Alex Honnold, each episode goes beyond the headlines to show what's actually working and who's making it happen. In partnership with the Rolex Perpetual Planet Initiative, this is Planet Visionaries. Listen or watch wherever you get your podcasts.

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• 2:59Speaker 01

  All right, Hannah, Elsa, we've got a lot to get into.

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  Let's start with ancient avocados.

• 3:04Speaker 03

  Is my avocado toast in danger here?

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  Well, not yet. So when you pick up avocados at the grocery store, or when you get guac in your burrito, chances are that it's from a single type of avocado. It's called the hass avocado.

• 3:16Speaker 03

  Right.

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  And Elsa, this type of avocado makes up more than 80% of commercial avocado production.

• 3:22Speaker 01

  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.

• 3:34Speaker 03

  Oh, like farmers are putting all their eggs, haha, 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?

• 3:47Speaker 02

  Yeah, there are. And a lot of them look very different.

• 3:50Speaker 05

  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.

• 3:59Speaker 02

  So this is archaeobotanist Kevin Wong. He's a fellow at the Smithsonian National Museum of Natural History and a PhD candidate at Texas A&M doing avocado research, even though, up until a couple of years ago, he'd never tasted one.

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  I was gonna see if I could go my entire PhD studying avocados without ever having eaten one or eaten guacamole.

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  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.

• 4:31Speaker 02

  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 23andMe or ancestry.com test, but for avocados.

• 4:42Speaker 03

  That's kind of cute. Okay, so what did they find?

• 4:46Speaker 01

  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.

• 5:05Speaker 02

  Then 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.

• 5:25Speaker 03

  Totally. But I am still dying to know, did Kevin ever eat an avocado?

• 5:31Speaker 02

  He did.

• 5:32Speaker 05

  When I was interviewing that farmer in Nicaragua, he picked off one of the avocado fruits and said, here, try this. And I couldn't say no.

• 5:39Speaker 03

  No, you couldn't.

• 5:40Speaker 02

  Exactly. And Elsa, you'll be happy to know that Kevin told me he eats avocados and guacamole almost every single day now.

• 5:47Speaker 03

  Good for him.

• 5:48Speaker 01

  Good man.

• 5:49Speaker 03

  So let's move on to Egyptian princesses. Tell me more.

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  Yeah. So maybe what I love most about this story is that it came from an effort to unclutter a basement.

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  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.

• 6:14Speaker 03

  Yeah, totally normal thing to find in one's basement.

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  Of course.

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  So who was this family?

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  It was five princesses and a king who lived thousands of years ago, around 1800 B.C.

• 6:25Speaker 03

  Wow, a girl dad.

• 6:26Speaker 02

  Yeah, exactly.

• 6:28Speaker 01

  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.

• 6:40Speaker 03

  Of course.

• 6:40Speaker 01

  So the assumption was the princesses were buried with these weapons for symbolic reasons.

• 6:45Speaker 03

  Symbolic? Wait, hello. Have these people not ever heard of Xena Warrior Princess? Because women do carry weapons sometimes, okay?

• 6:54Speaker 02

  Exactly. And that's what the person who helped find these remains wanted to figure out.

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  Yeah, her name is Xenab Hashish. She's a bioarchaeologist at Beni Swef University in Egypt. And she says, you know, we all have this assumption that princesses are like Disney characters.

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  That they are fluffy. They are wearing beautiful dresses and very beautiful jewelry.

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  When Xenab looked at these bones, she noticed that these skeletons had really strong muscle attachments.

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  These women were buff.

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  Exactly. And she did a deeper analysis of the bones, and she found these women were, yeah, buff. They were really strong.

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  Strong forearms and shoulder. And also, for example, Princess Nuphat, her right second hand bone shows a unique curve.

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  And that curve, Elsa, likely came from the repeated use of a bow and arrow.

• 7:44Speaker 03

  Wow. Wait, so these women literally were warrior princesses?

• 7:48Speaker 01

  Well, Xenab says it's unclear if these findings, which were published in the journal Frontiers in Environmental Archaeology, prove 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 the study. But he says it does show that their lives weren't as relaxed as we might have thought, that they did real work.

• 8:06Speaker 03

  They were shooting bows and arrows. All right, our final topic is birdsong. What are you gonna tell me about singing birds?

• 8:14Speaker 01

  Yeah, so this study analyzed more than 116,000 birdsongs from perching birds, which include, you know, robins and thrushes, warblers and crows, and on and on.

• 8:23Speaker 03

  Cool. Okay, so what were the scientists looking for specifically in all of these birdsongs?

• 8:28Speaker 01

  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.

• 8:36Speaker 02

  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.

• 8:47Speaker 03

  Okay, so what are the eight different motifs?

• 8:50Speaker 01

  So there are three different types of trills. There is a slow trill sung here by a northern cardinal recorded outside of Minneapolis.

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  And an ultrafast trill.

• 9:07Speaker 03

  Whoa. Was that the ultrafast I just heard?

• 9:10Speaker 01

  Ultrafast.

• 9:10Speaker 02

  Yeah. And that one's sung by a Bohemian waxwing in the Canadian province of Newfoundland and Labrador.

• 9:16Speaker 03

  That's amazing. It was almost like, I don't know, like a drill.

• 9:19Speaker 01

  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 birders uploaded songs.

• 9:28Speaker 02

  And we don't have time to cover all eight of them. But another pattern that's maybe worth knowing is the flat whistle.

• 9:36Speaker 01

  That's sung by a three-waddled 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.

• 9:49Speaker 03

  Wait, so that flat whistle call, does that give them some kind of advantage?

• 9:54Speaker 02

  Well, it's simple and it's loud, so it can be heard in a wide area. Here's the lead author of the study, Quentin Biqueli. He's a PhD candidate studying bioacoustics in Paris.

• 10:04Speaker 07

  So that's really impressive to see that nature found the same solutions for the same constraints, but across different parts of the world.

• 10:13Speaker 01

  So in other words, Elsa, birds separated by oceans and continents all landed independently on the same types of acoustic patterns to communicate.

• 10:22Speaker 03

  That is so cool.

• 10:23Speaker 01

  Well, Elsa, thank you so much for geeking out with us this week. Come back anytime.

• 10:27Speaker 03

  Always. It's so fun to hang with you guys.

• 10:29Speaker 01

  You can hear more of Elsa Chang on Consider This, NPR's afternoon podcast about what the news means for you.

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  And for more science stories just like this one, follow Short Wave on whatever app you're listening to.

• 10:41Speaker 01

  This episode was produced by Burley McCoy and Jordan Marie Smith. It was edited by Lauren Gonzalez, Rebecca Ramirez, and Christopher Intagliata.

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  Tyler Jones checked the facts. Anlee Wong, Robert Rodriguez, and Peter Elena were the audio engineers. I'm Hannah Chen.

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  And I'm Nate Rot. Thanks for listening to Short Wave, the science podcast from NPR.

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