The primitive brain of early <i>Homo</i>.

Abstract

The brains of modern humans differ from those of great apes in size, shape, and cortical organization, notably in frontal lobe areas involved in complex cognitive tasks, such as social cognition, tool use, and language. When these differences arose during human evolution is a question of ongoing debate. Here, we show that the brains of early <i>Homo</i> from Africa and Western Asia (Dmanisi) retained a primitive, great ape-like organization of the frontal lobe. By contrast, African <i>Homo</i> younger than 1.5 million years ago, as well as all Southeast Asian <i>Homo erectus</i>, exhibited a more derived, humanlike brain organization. Frontal lobe reorganization, once considered a hallmark of earliest <i>Homo</i> in Africa, thus evolved comparatively late, and long after <i>Homo</i> first dispersed from Africa.