Research from Harvard University suggests fermentation, not fire, drove our ancestors’ bigger brains. Researchers tracked when human brains tripled in size during evolution from Australopithecines.
It’s a mystery why our brains matured at the times they did. While some believed cooking was the cause, a recent theory claims fermentation was involved. Erin Hecht, author of ‘Fermentation Technology as a Driver of Human Brain Expansion,’ suggests our diet is the key.
Hecht, an assistant professor of human evolutionary biology, said, “Brain tissue is metabolically expensive. It requires many calories to keep it running, and in most animals, having enough energy to survive is a constant problem.”
To survive with larger brains, Australopithecus likely changed their diet. Early theories suggest cooking boosted usable calories, but evidence shows fire use came later than brain growth. Katherine L. Bryant, co-author, notes a gap of about 1 million years between brain growth and cooking emergence. Another dietary change, like fermentation, may have eased metabolic constraints.
Hecht suggests that dietary changes occur before brain growth. Besides rotting meat, the team proposes a new idea: fermented cached food. This ‘pre-digested’ food offered more accessible nourishment, supporting brain growth and aiding survival through natural selection.
Hecht stated, “It was probably an inadvertent shift. It may have begun as unintentional food storage. Traditions or superstitions may have encouraged fermenting methods over time. Our smaller large intestine supports this theory by suggesting an adaptation to pre-digested food. Fermented foods are widely available, from European cheese and wine to natto and soy sauce in Asia.”
Hecht advocates using ancient DNA to explore the brain’s reactions to fermented foods and olfactory/taste receptors. Bryant advocates for more research on the effects of fermented foods on gut flora and health because she sees potential advantages. Recent studies link gut health to both physical and mental well-being.
The idea that fermented foods help our brains grow gives us a new way to look at human development. However, more research from different fields is needed to understand how fermented foods affect our evolution, health, and overall well-being.
Journal reference:
- Bryant, K.L., Hansen, C. & Hecht, E.E. Fermentation technology as a driver of human brain expansion. Communications Biology. DOI: 10.1038/s42003-023-05517-3.