When and why did human brains decrease in size 3,000 years ago? Ants may hold clues

The brain is the most complex organ in the human body. Now, a new study has brought us closer to understanding some of its evolution. It shows that human brains decreased in size approximately 3,000 years ago. By studying ants as models to illustrate why brains may increase or decrease in size, the researchers hypothesize that brain shrinkage parallels the expansion of collective intelligence in human societies.