“The Expensive-Tissue Hypothesis” foreslår, at store hjerner hos mennesker og primater udviklede sig gennem en afvejning med et mindre fordøjelsessystem. En højkvalitetsdiæt reducerede energibehovet til maven, hvilket frigjorde energi til hjernen. Studien viser en omvendt sammenhæng mellem hjerne- og mavestørrelse hos primater.
Titel på undersøgelse:
The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution.
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Hele abstrakt på originalsprog:
The study introduces the expensive-tissue hypothesis, proposing that the evolution of large brains in humans and primates required a trade-off with other metabolically costly tissues, particularly the digestive system. Analyzing data across primate species, Aiello and Wheeler demonstrate an inverse correlation between brain size and gut size, suggesting that a reduced digestive tract—enabled by a higher-quality, easier-to-digest diet—freed up energy for brain expansion. Unlike heart, liver, or kidneys, which show no consistent size reduction with larger brains, the gut’s shrinkage aligns with metabolic constraints, as both organs demand significant energy. This adaptation likely coincided with dietary shifts, such as increased meat consumption or cooking, reducing digestive workload. The hypothesis reframes brain evolution as a systemic energetic balance, challenging views focused solely on cognitive pressures, and calls for further research into diet’s role in primate evolution.