Human brains grew throughout evolutionary history, but about 3,000 years ago, they shrunk noticeably. Why? A group of scientists from diverse fields looked at an unlikely source—ant colonies—to propose an answer. They hypothesize that human brain size decreased as our societies became more complex. As people started making decisions as a group, and dividing up labour, they could rely more on other peoples’ knowledge, allowing their individual brains to become smaller and more efficient.

Learn more about this amazing finding here, on