Human evolution: brains grow, colons shrink (Introduction)

by David Turell , Sunday, December 03, 2023, 16:06 (146 days ago) @ David Turell

From a story about u sing fermented foods:

https://www.sciencealert.com/preparing-food-with-microbes-could-be-why-we-now-have-such...

"Researchers propose that a taste for fermented morsels may have triggered a surprising jump in the growth rate of our ancestors' brains.

"In fact, a shift from a raw diet to one that included food items already partially broken down by microbes may have been a crucial event in our brain's evolution, according to a perspective study by evolutionary neuroscientist Katherine Bryant of Aix-Marseille University in France and two US colleagues.

"Human brains have tripled in size over the last two million years of evolution, while human colons have shrunk by an estimated 74 percent, suggesting a reduced need to break down plant-derived food internally.

"We know the timeline and extent of human brain expansion, but the mechanisms allowing energy to be directed to this expansion are more complex and somewhat debated.

The study authors lay out their "external fermentation hypothesis" which shows our ancestors' metabolic circumstances for selective brain expansion may have been set in motion by moving intestinal fermentation to an external process, perhaps even experimenting with preserved foods not unlike the wine, kimchi, yoghurt, sauerkraut, and other pickles we still eat today.

"The human gut microbiome acts like a machine for internal fermentation, which boosts nutrient absorption during digestion. Organic compounds are fermented into alcohol and acids by enzymes, usually produced by the bacteria and yeasts that live in parts of our digestive system such as our colon.

"Fermentation is an anaerobic process, meaning it doesn't require oxygen, so similar to the process in our guts, it can occur in a sealed container. The process produces energy in the form of adenosine triphosphate (ATP), which is an essential source of chemical energy that powers our metabolism.

"The researchers argue it's possible that culturally passed-down ways of handling or storing food encouraged this function to be externalized."

Comment: fermentation of food may have played a role, or not. The striking information offered is comparing human organ sizes with great ape proportions. Our brain is three times larger and our colon one-fourth the size. Our small intestine is twice as large, while other gut parts in humans are one-third ape size. (See the diagram) Obviously what we eat dictates how the gut changed to handle it. From my viewpoint, God may have helped in the design of brain and gut changes.