The world, the universe and us Why we can't announce life on Mars (yet); The Romans' impact on the British economy; Link between exercise and your microbiome
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Sep 12, 2025 In this conversation, Mike Marshall, a science writer discussing Roman history, unveils surprising evidence that the withdrawal of the Romans from Britain wasn't as catastrophic as once thought; instead, it may have sparked a metalworking boom. Meanwhile, Sanjeev Gupta, an extraterrestrial geologist, shares thrilling insights from NASA's latest findings on Mars, suggesting signs of past microbial life. They also explore the fascinating link between weightlifting and gut health, revealing how exercise can boost beneficial bacteria in our microbiome.
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Speckled Mudstones Strengthen Mars Life Case
- Perseverance found speckled mudstones in Bright Angel that show redox-linked mineral patterns tied to organics.
- The uneven distribution of these speckles strengthens the case that biology could have driven those redox reactions on ancient Mars.
Redox Chemistry Favors Biological Explanation
- Redox reactions move electrons and release usable energy, which organisms on Earth exploit for metabolism.
- Abiotic routes to produce the observed sulfides would require much higher temperatures than those inferred for the Martian sediments, making biology a plausible explanation.
Geological Context Makes The Find Compelling
- Bright Angel mudstones are fine-grained, laminated lake deposits with organics and reduction spots of sulfides and phosphates.
- The contextual combination of habitable environment, organics, and redox features makes this a potential biosignature worth returning to Earth for testing.