The Expensive Tissue Hypothesis

The Expensive Tissue Hypothesis suggests that because brain tissue consumes a lot of energy, humans and some primates evolved smaller guts (digestive systems) to free up energy for brain development. Essentially, there's a trade-off: energy spent on maintaining large, energy-intensive organs like the brain means less energy can go toward other organs, so our ancestors balanced this investment by having more efficient digestion. This allows for a bigger, more complex brain without requiring an overall increase in total energy intake, highlighting how evolutionary changes often involve reallocating resources for survival advantages.