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 Homo from Africa and Western Asia (Dmanisi) retained a primitive, great ape–like organization of the frontal lobe. By contrast, African Homo younger than 1.5 million years ago, as well as all Southeast Asian Homo erectus, exhibited a more derived, humanlike brain organization. Frontal lobe reorganization, once considered a hallmark of earliest Homo in Africa, thus evolved comparatively late, and long after Homo first dispersed from Africa.

现代人类的大脑在大小，形状和皮层组织方面与大猿类的大脑不同，特别是在涉及复杂认知任务（如社会认知，工具使用和语言）的额叶区域。当这些差异在人类进化过程中出现时，就是一个不断争论的问题。在这里，我们证明了来自非洲和西亚（Dmanisi）的早期人类的大脑保留了原始的，类似于猿的额叶组织。相比之下，非洲智人年轻的超过150万年前，以及所有东南亚直立人，表现出更多的衍生，像人一样的大脑组织。额叶重组曾经被认为是最早的人的标志在非洲，这种进化相对较晚，而在人类首次从非洲散布很久之后。