People often assume that evolution has progressed in an upward trajectory, from simple organisms to more complex ones. Because humans have such sizable brains (more specifically, our intelligence relates to the brain-to-body mass and cerebral cortex ratios), one might assume that we’re the most evolved. We have defined our animal kingdom superiority in terms of our smarts and our ability to think rationally. If we are supposedly at the pinnacle of evolution, then our brains must have evolved for thinking, right?
In reality, the content between our two ears may have transformed for far more rudimentary reasons.
[Neuroscientist and psychologist Lisa Feldman] Barrett describes how ancient evolutionary pressures, like adapting to predator-prey relationships, propelled creatures to evolve bigger, more sophisticated bodies. With larger machinery, and more complex internal systems, body budgeting became a much more elaborate task.
Creatures needed to process an increasing number of variables, such as managing developing circulatory and immune systems, when assessing whether a withdrawal from their body budget would be worth it. In turn, they needed something that could process these variables. They needed a big brain.
Yes, that’s right. Brains didn’t evolve to help us ponder life’s philosophical questions. Instead, they emerged as the control center for body budgeting.