A group of scientists made headlines last year when they came to the conclusion that the human brain shrank around 3,000 years ago during the transition to modern urban societies because our ancestors' ability to store information externally in social groups reduced the need for us to maintain large brains. Based on a comparison to evolutionary trends observed in ant colonies, their concept investigated decades-old theories on the evolutionary decline of present human brain size.

A new UNLV-led team examined the dataset that the research team from the previous study utilized in a new work that was published last week in Frontiers in Ecology and Evolution1 and rejected their conclusions. According to the UNLV team, the development of sophisticated communities and agriculture took place at various times throughout the world, therefore there should be diversity in the timing of changes to the skull that are observed in various populations.

The prior collection seemed very selective and only included 23 crania from the crucial time period for the brain shrinkage hypothesis and combined samples from places like England, China, Mali, and Algeria. More over half of the 987 skulls investigated reflect only the last 100 years of a 9.8-million-year period of time, which severely skews the dataset and prevents scientists from determining how much cranial size has changed over time.