Core Argument

The barrier to preying on "mirror-image" life is likely lower than presumed due to:

Immediate energy from achiral fats.
Existing L-sugar pathways.
Existing D-amino acid racemases.

1. Fats: Achiral Energy Bridge

Lipids (triglycerides), largely achiral, offer immediate energy. In E. coli for example, they constitute ~10% of dry mass, yielding ~27% of its macronutrient calories[1]). This non-chiral caloric gain from mirror prey could sustain predators during adaptation to chiral components.

2. Carbohydrates: L-Glucose Metabolism Evolved

L-glucose metabolism has evolved at least twice despite its rarity in nature:

Pseudomonas caryophylli enzyme oxidizes L-glucose (Sasajima & Sinskey, 1979[2]).
Paracoccus sp. 43P has a full L-glucose catabolic pathway (Shimizu et al., 2012[3]). This capacity for mirror-sugar adaptation, emerging even under low selective pressure, suggests the evolutionary barrier to such adaptations might be lower than anticipated.

[...]

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Outline:

(00:10) Core Argument

(00:30) 1. Fats: Achiral Energy Bridge

(00:56) 2. Carbohydrates: L-Glucose Metabolism Evolved

(01:35) 3. Proteins: Racemases Handle D-Amino Acids

(02:09) Conclusion: Lowered Mirror Predation Barrier

The original text contained 4 footnotes which were omitted from this narration.

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First published:
May 22nd, 2025

Source:
https://www.lesswrong.com/posts/zA6HWeoMeJWcrsfgK/mirror-organisms-are-not-immune-to-predation

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Narrated by TYPE III AUDIO.

“Mirror Organisms Are Not Immune to Predation” by Matthias Dellago

LessWrong (30+ Karma)