Decades of research suggest that our brains have shrunk over time, but not all scientists agree.

Researchers refute a hypothesis that the human brain shrank 3,000 years ago as a result of the transition to living in modern societies.

No, we aren’t devolving: Human brain size hasn’t changed since Jebel Irhoud Person stalked the Sahara 300,000 years ago, says new team

Humans are proud of their brainpower. Our noggins are some of the largest nature has to offer, and we like to think that we are an intelligent species.

Last year, an article published to Frontiers in Ecology and Evolution made headlines across the world after it claimed human brains shrank in size approximately 3,000 years ago. This, according to the authors, may have driven by the externalization of knowledge in human societies, thus needing less energy to store a lot of information as individuals. As a result, we developed smaller brains.

Until now, our brains were thought to be bigger than they are today. They would have gone through a sudden contraction about 3000 years ago. Scientists are now coming back to that.

Did human brains shrink 3,000 years ago, downsizing by an amount equal to around four ping-pong balls?

Humans take a lot of pride in their brains. We like to think we are an intelligent species, and even though size isn't everything, our noggins are some of the largest nature has to offer.

According to research conducted in 2019, the human being underwent brain shrinkage 3,000 years ago. According to the authors, the reason was the ease of storing information in social groups. Thus, humans stopped containing in their brain all the information they needed to survive and began to rely on social or collective intelligence. This study was based on the evolutionary patterns of ants , due to the social organization of said insects. Despite the solid analysis that the scientists did, it may be that their proposal is not so accurate.

For decades, scientists have heralded the idea that human brains have increased in size over the course of history, evolving in modern humans be much larger than that of our Neanderthal cousins. In October 2021, DeSilva et al., seemingly added more evidence to this hypothesis with a paper that concluded the human brain shrank during the transition to modern urban societies about 3,000 years ago. And while this supported previous literature, the research did establish a new timeline—marking brain decrease as late as the last Ice Age.

Did the 12th century B.C.E. — a time when humans were forging great empires and developing new forms of written text — coincide with an evolutionary reduction in brain size? Think again, says a UNLV-led team of researchers who refute a hypothesis that’s growing increasingly popular among the science community.

Anthropologists believe that brain size has remained dynamic in size. It nearly quadrupled in the six million years since Homo last shared a common ancestor with chimpanzees, but human brains are thought to have decreased in volume since the end of the last Ice Age.