Podcast Summary: "Intraterrestrials"
Podcast: Unexplainable
Host/Author: Vox
Release Date: April 2, 2025

Introduction

In the episode titled "Intraterrestrials," the Unexplainable team delves into the mysterious world of deep-sea microbes that challenge our fundamental understanding of life. Hosted by Bird Pinkerton, with insights from microbiologist Karen Lloyd, the episode explores how these tiny organisms defy biological norms and what their existence means for the broader scientific community.

The Enigmatic World of Intraterrestrial Microbes

Bird Pinkerton begins the discussion by painting a vivid picture of single-celled organisms dwelling in the ocean mud:

"[01:02] Imagine that you are a single celled organism. You live on the ocean floor, perched on the mud there..."

These microbes, termed "intraterrestrials" by Karen Lloyd, resemble extraterrestrial life forms due to their extraordinary adaptations and enigmatic existence. Karen Lloyd explains their peculiar lifestyle:

"[01:34] It's the slow and steady rain of the leftovers of what everything else in the ocean has eaten and pooped and died, settling very, very slowly over your head..."
"[02:15] They are alien to us in the real sense of the word alien."

Defying Biological Assumptions

Karen Lloyd highlights how these microbes challenge traditional biological theories:

"[05:21] You know, it's kind of like if somebody gave you a pizza to eat for lunch, and then they were like, oh, wait, this is all the food you're ever going to get for the rest of your life. Make it last."

These organisms survive on minimal energy—thousands of times less than what is considered necessary for life. This energy scarcity questions the fundamental assumption that life requires regular energy intake to sustain growth, movement, and reproduction. Karen emphasizes:

"[07:14] It would take to make a whole new daughter cell to do that process. They just, they can't. I mean, it's barely enough even to survive."

The Longevity Conundrum

One of the most perplexing aspects is the apparent longevity of these microbes. Samples retrieved from ocean mud suggest that some of these cells may be millions of years old:

"[08:10] The only conclusion we can make from that is that that is the same cell that was laid down at the surface like a million years ago."

Karen Lloyd reflects on this astonishing finding:

"[08:35] That's kind of crazy, but it is a reasonable conclusion from our data."

This longevity challenges biological theories that link reproduction and evolution. If these microbes do not reproduce over such extended periods, the mechanisms of natural selection and evolutionary adaptation become unclear.

Evolution Without Reproduction

Addressing the evolutionary puzzle, Karen discusses the incompatibility of non-reproductive existence with Darwinian evolution:

"[09:42] ...it gets in a little bit of trouble with Charles Darwin."
"[12:38] This is very, very well known. We see no exceptions from it in all of biology."

Despite these challenges, Karen proposes a hypothesis that these microbes have evolved to thrive under extreme energy scarcity by entering a state akin to hibernation. This state allows them to survive until environmental conditions improve, enabling occasional reproduction:

"[13:11] It feels like an impossible riddle almost. But Karen does think that it is possible to imagine a solution here."

Geological Interactions: The Path to Revival

Karen suggests that geological processes might eventually provide the necessary conditions for these microbes to emerge from their dormant state:

"[16:00] ...the mud that it's sitting in, that mud is on top of a tectonic plate..."
"[17:17] They might be waiting for a spring that we will never live to see."

The movement of tectonic plates could alter their environment, introducing new sources of energy that awaken the microbes from their extended dormancy:

"[17:51] ...this springtime bonanza could maybe shock these microbes out of hibernation."

Natural Selection Over Millennia

This prolonged dormancy followed by sporadic bursts of activity would enable natural selection to act over geological timescales. Only the most resilient microbes survive these extended periods of scarcity, gradually shaping their unusual characteristics:

"[18:22] ...only the hardiest microbes, the ones that are best at hibernating, only they make it through the winter millennia and emerge in spring to bloom and reproduce."

Karen summarizes her hypothesis:

"[19:46] ...this scenario sounds crazy, but it is reasonable."
"[19:56] Karen's still working on ways to test her hypothesis, but ultimately,..."

The Broader Implications: Rethinking Life

Beyond solving the riddle of intraterrestrial microbes, this discovery prompts a reevaluation of life’s possibilities:

"[21:21] ...life was not confined to this narrow subset of possibilities."
"[21:46] ...we could be living on a planet that's simply crawling with tiny aliens, each with their own riddles to solve."

Karen expresses her excitement about the potential for discovering more such organisms:

"[22:05] It's almost like I get a whole new Earth to play with and to think about."

Conclusion

"Intraterrestrials" offers a captivating exploration into the unknown realms of microbiology, where life forms challenge our deepest biological understandings. Karen Lloyd and Bird Pinkerton present a thought-provoking investigation into how these microbes survive in extreme conditions, potentially rewriting the rules of evolution and longevity. This episode not only uncovers scientific mysteries but also ignites the imagination about the diverse forms life can take on Earth.

Notable Quotes:

• Karen Lloyd ([05:21]): “...it's kind of like if somebody gave you a pizza to eat for lunch, and then they were like, oh, wait, this is all the food you're ever going to get for the rest of your life. Make it last.”

• Karen Lloyd ([08:10]): “The only conclusion we can make from that is that that is the same cell that was laid down at the surface like a million years ago.”

• Karen Lloyd ([12:38]): “This is very, very well known. We see no exceptions from it in all of biology.”

• Karen Lloyd ([19:46]): “We know for a fact that these organisms are there, and we know that nothing has happened to them for this long. And we know how much energy they have...”

• Karen Lloyd ([21:21]): “I think that life was not confined to this narrow subset of possibilities.”

Additional Information

For those intrigued by the mysteries of intraterrestrial microbes and Karen Lloyd's research, her upcoming book titled Intra Terrestrials is available for pre-order. Dive deeper into the hidden lives of these ancient organisms and explore the broader implications for our understanding of life on Earth.

Production Credits:

• Produced by: Bird Pinkerton
• Edited by: Meredith Hoddinott
• Music by: Noam Hassenfeld
• Mixing and Sound Design: Christian Ayala
• Fact-Checked by: Melissa Hirsch, Julia Longoria

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