A new study has brought us closer to understanding some of the brain’s evolution, Phys.org reports. It shows that human brains decreased in size approximately 3,000 years ago. In studying ants as models to illustrate why brains may increase or decrease in size, researchers hypothesize that brain shrinkage parallels the expansion of collective intelligence in human societies. “A surprising fact about humans today is that our brains are smaller compared to the brains of our Pleistocene ancestors. Why our brains have reduced in size has been a big mystery for anthropologists,” explained co-author Dr. Jeremy DeSilva, from Dartmouth College. To disentangle this mystery, a team of researchers from different academic fields set out to study the historical patterns of human brain evolution, comparing their findings with what is known in ant societies to offer broad insights. The researchers found that the timing of size increase coincides with what is previously known about the early evolution of Homo and the technical advancements that led to; for example, better diet and nutrition and larger social groups. “We propose that ants can provide diverse models to understand why brains may increase or decrease in size due to social life. Understanding why brains increase or decrease is difficult to study using only fossils,” explained Traniello.