The left and right sides of our brains aren’t symmetrical; some areas on one side are larger or smaller, while other parts protrude more.
The pattern of these anatomical differences, or asymmetries, was thought to be uniquely human, originating when our brain hemispheres became specialised for certain tasks, such as processing language with the left side.
Now, it seems the pattern came first – before humans evolved. Brain pattern comparisons between humans, chimpanzees, gorillas and orangutans reveal that our brains’ left-right differences aren’t unique, but shared with great apes.
“It suggests it is an ancestral pattern that was established far earlier during evolution, before the split of human and great apes lineages,” says Simon Neubauer at the Max Planck Institute for Evolutionary Anthropology in Germany.