Short Wave – Episode Summary

Episode: "Could labs replace your natural chocolate?"

Date: August 22, 2025
Hosts: Emily Kwong, Hannah Chin
Guest: Mary Louise Kelly (from All Things Considered)
Length: ~10 minutes (core content)

Overview

This fast-paced episode of Short Wave dives into three intriguing science stories:

1. How microbes shape the complex flavors of chocolate and whether lab techniques could one day "replace" traditional chocolate fermentation.
2. The surprisingly frequent bathroom habits of seabirds at sea and the ecological importance of their excretions.
3. New research into blood metabolites and what they reveal about why some people are sleepier during the day—even with enough rest.

Throughout the episode, the hosts bring lively banter, curiosity, and humor, making complex science fun and accessible.

Key Discussion Points & Insights

1. Could Labs Replace Your Natural Chocolate?

[02:12–04:13]

• The Science Behind Chocolate Flavor

  • Research published in Nature Microbiology focuses on how microscopic communities (microbes) on cocoa beans influence chocolate’s taste.
  • Chocolate flavors vary according to where cocoa is grown—flavors can be "fruity or floral or spicy" (Hannah Chin, [02:28]).
  • Scientists from the University of Nottingham wanted to understand which microbes contribute to these flavor profiles.

• Microbial Fermentation

  • Fermantation is a crucial step after beans are harvested—microbes create flavor compounds.
  • "It's during fermentation that these microbial communities emerge and they give rise to all kinds of flavor compounds for the chocolate." (Emily Kwong, [03:03])

• Synthetic Fermentation in the Lab

  • Scientists sequenced DNA from microbial samples on Colombian farms, modeled their interactions, and then created a "cocktail" of these microbes to ferment cocoa beans directly in the lab.
  • Lab fermentation successfully produced distinct chocolate flavors, confirmed by professional tasters as similar to high-quality chocolate.

• Implications for the Cocoa Industry

  • Potential to make chocolate production more predictable amid worldwide cocoa shortages due to climate change.
  • Raises ethical and economic questions for small farmers if lab-based techniques become widespread.
  • "If scientists can just create, recreate chocolate flavors in a lab, what does that mean for the poor cocoa bean and for small time chocolate farmers?" (Mary Louise Kelly, [03:59])

2. Seabirds' Astonishing Bathroom Habits at Sea

[04:13–06:47]

• Accidental Discovery

  • University of Tokyo postdoc Leo Uesaka, studying seabird movement, noticed unexpected data from cameras strapped to streaked shearwaters' bellies.

• An Unexpected Pattern

  • Seabirds were "almost always took off to poop" ([05:00], Hannah Chin).
  • Analysis of 30+ hours of footage showed seabirds defecate every 4–10 minutes while at sea, regardless of eating habits.
  • This results in birds losing 5% of their body mass every hour from defecation. (Leo Uesaka, via Emily Kwong, [05:25])

• Scientific Significance

  • Previous estimates of seabird poop were based on land observations; this is a rare glimpse into behavior at sea.
  • Guano is vital for nutrient cycling in the ecosystem. The study affects how researchers estimate seabird food needs—a critical input for fishing regulations and conservation.

• Ecological Implications

  • "If we are underestimate how much poop they are doing and it probably is connecting with how much food they are taking, we also underestimate how much food they need." (Daniel Plaza, [06:36])

3. What Makes Us Sleepy During the Day?

[06:57–09:31]

• Prevalence of Excessive Daytime Sleepiness (EDS)

  • "This condition affects up to one in three people in the U.S. it's very common." (Emily Kwong, [07:11])
  • EDS can occur even when people get enough sleep at night; it is associated with higher risks of cardiovascular conditions.

• Measuring Sleepiness

  • The Epworth Sleepiness Scale is a survey that assesses how likely a person is to doze off during various daily activities.

• The Role of Blood Metabolites

  • Researchers surveyed 6,000 individuals, then analyzed their blood for 877 molecules (metabolites) potentially linked to sleepiness.
  • Ten metabolites were found to have significant associations—some increasing, some decreasing the likelihood of feeling sleepy.

• Key Findings

  • "A metabolite of tyramine, which is found in fermented foods, aged cheese and alcohol was associated with higher rates of self reported daytime sleepiness, particularly in men." (Emily Kwong, [08:46])
  • Omega 3 and 6 fatty acids (in fish, vegetable oils, nuts, and seeds) correlated with less sleepiness.

• Implications for Diet

  • Too early for dietary recommendations; future clinical trials are planned.
  • "Your charcuterie board is doomed." (Emily Kwong poking fun, [09:17])

Notable Quotes & Memorable Moments

• Microbial Mystery:
  "The level of microbes. So very, very tiny microorganisms. How are microbes involved and how chocolate tastes, well?"
  —Mary Louise Kelly ([02:45])

• Willy Wonka Science:
  "Then they went full Willy Wonka."
  —Hannah Chin ([03:31])

• Lab Chocolate Taste:
  "The beans fermented with a synthetic microbial community exhibited flavor notes similar to fine chocolate."
  —Emily Kwong ([03:42])

• Seabirds Science Humor:
  "Such a labor of love."
  —Mary Louise Kelly, about analyzing seabird footage ([05:23])

• Poop and Conservation:
  "If we are underestimate how much poop they are doing and it probably is connecting with how much food they are taking, we also underestimate how much food they need."
  —Daniel Plaza ([06:36])

• Sleepiness and Cheese:
  "Your charcuterie board is doomed."
  —Emily Kwong ([09:17])

Timestamps for Key Segments

| Time | Segment Description | |--------|-----------------------------------------------| | 02:12 | Introduction to chocolate flavor research | | 03:03 | Importance of microbial fermentation | | 03:31 | Lab-created chocolate flavors | | 03:59 | Social/economic implications of lab chocolate | | 04:13 | Seabird bathroom behavior discovery | | 05:25 | Seabird excretion frequency and mass loss | | 06:36 | Ecosystem links: poop, fish, and conservation | | 06:57 | Introduction to sleepiness research | | 07:40 | Survey method for sleepiness (Epworth scale) | | 08:46 | Metabolite findings: tyramine and sleepiness | | 09:07 | Omega-3s, omega-6s, and less sleepiness |

Summary

This episode of Short Wave delivers bite-sized but impactful science. From the future possibilities of lab-fermented chocolate (and concerns for farmers), through the surprising ecological implications of seabird bathroom habits, to the molecules in our blood that may be making us sleepy, the show brings rigorous research and irrepressible curiosity. Playful banter ("Your charcuterie board is doomed") and enthusiastic questioning ("How are microbes involved and how chocolate tastes, well?") make this episode a lively listen for any science lover.