Image of the Day: Brains and Braincases
Image of the Day: Brains and Braincases

Image of the Day: Brains and Braincases

The skull changed shape in different ways than the brain during evolution, according to a new comparative study.

Emily Makowski
Oct 18, 2019

ABOVE: CT/MRI skull and brain imaging data of a human (left), a chimpanzee (center), and a gorilla (right)

During the course of human evolution, our hominin ancestors’ brains changed shape; so did the braincase, the part of the skull surrounding the brain. A team of researchers led by José Luis Alatorre Warren at the University of Zurich published a paper in PNAS October 14 suggesting that changes in these structures evolved independently of each other.

The researchers compared computed tomography and magnetic resonance imaging data of human, chimpanzee, and gorilla brains and braincases to analyze their shapes within and across primate species. They found that human brains were three times bigger than those of great apes and had undergone spatial reorganization during evolution resulting in specialized areas such as those for speech. These changes did not lead to similar changes in the human braincase, however. Instead, the human skull mainly shows adaptations for walking upright, such as a rostral shift forward in the opening for the spinal cord.

Visualization of the differences between average human (blue) and chimpanzee (red) brains and braincases
José Luis Alatorre Warren

J.L.A. Warren et al., “Evidence for independent brain and neurocranial reorganization during hominin evolution,” PNAS, doi:10.1073/pnas.1905071116, 2019.

Emily Makowski is an intern at The Scientist. Email her at