Our bulbous brains require a lot of energy to function. Like, a lot of energy. That one organ alone requires 25% of our body's total fuel stores. So from an energy allocation perspective — and thus from an evolutionary perspective — it sure as hell better be worth it.

Other animals haven’t had to make these sorts of Darwinian adjustments. Herd animals and insect swarms, while social, take on loose social arrangements that are typically based on short-term advantages.

But other animals, like primates, whales, dolphins, and elephants, have social lives that are far more dynamic, often involving intense coordination with multiple group members. And it’s no coincidence, say some scientists, that these animals have powerful and complex cognitive capacities.

And indeed, the social brain theory suggests that brain size affects the speed, volume, and sophistication of decisions that can be made amongst interacting individuals.