Study puts fermented foods, not fire, as pivotal moment in human brain growth

Competing hypotheses for brain growth and gut reduction

• Thread contrasts the new “external fermentation” hypothesis with existing ideas: increased meat consumption, cooked food, tubers/starches, and general food processing (milling).
• Smaller human colons vs other primates are variously interpreted as: adaptation to more bioavailable food (meat), reduced reliance on fibrous plants, or reliance on externally fermented foods.
• Some argue multiple factors (meat, fire, fermentation, social complexity) likely interacted, not a single “magic” driver.
• Others question why large brains needed special dietary changes when gorillas can sustain massive muscle on low-quality plant diets simply by eating more; counterpoint: human-like guts are too small to support that strategy.

Plausibility of early fermentation

• Supporters note that warm climates and basic carrying/storage (gourds, leaves, simple caches) make accidental fermentation almost inevitable.
• Critics see it as a stretch that pre-fire hominins used fermentation consistently enough, over generations, to drive evolution.
• The paper itself compares explanatory power vs meat-, tuber-, and cooking-based hypotheses, but remains a hypothesis with proposed tests, not direct evidence.

Meat, carrion, and raw diets

• Discussion that early humans were likely scavengers/carrion feeders with highly acidic stomachs, possibly accessing pre-digested contents of prey stomachs.
• Debate on whether humans can thrive long-term on raw animal foods vs needing cooking or fermentation.
• Shorter, simpler guts are characteristic of carnivores; this might permit large brains but doesn’t guarantee their evolution without strong selection for cognition.

Fermented foods, microbiome, and health

• Many examples of traditional fermented foods (yogurt, kefir, natto, salami, fermented fish, idli, kiviak, hakarl, kvass, kombucha) are discussed as nutrient sources, preservatives, and microbiome modulators.
• Some praise fermented foods as “vital” or broadly beneficial; others warn about safety (food poisoning, dairy fermentation risks) and overhype.
• Gut microbiome is framed as a major, possibly underappreciated factor in health and even mental states.

Study status and source bias

• Multiple commenters stress the Nature paper is a speculative “external fermentation hypothesis,” not a data-heavy experimental study.
• Debate over whether calling it a “study” misleads the public about its evidential strength.
• Some criticize the submission source (a plant-based advocacy site) as agenda-driven; others note the underlying paper is independent and peer-reviewed, and that advocacy outlets naturally cherry-pick supportive research.