Semendeferi K, Damasio H
Department of Anthropology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92098-0532, USA.
J Hum Evol. 2000 Feb;38(2):317-32. doi: 10.1006/jhev.1999.0381.
Primary comparative data on the hominoid brain are scarce and major neuroanatomical differences between humans and apes have not yet been described satisfactorily, even at the gross level. Basic questions that involve the evolution of the human brain cannot be addressed adequately unless the brains of all extant hominoid species are analyzed. Contrary to the scarcity of original data, there is a rich literature on the topic of human brain evolution and several debates exist on the size of particular sectors of the brain, e.g., the frontal lobe. In this study we applied a non-invasive imaging technique (magnetic resonance) on living human, great ape and lesser ape subjects in order to investigate the overall size of the hominoid brain. The images were reconstructed in three dimensions and volumetric estimates were obtained for the brain and its main anatomical sectors, including the frontal and temporal lobes, the insula, the parieto-occipital sector and the cerebellum.A remarkable homogeneity is present in the relative size of many of the large sectors of the hominoid brain, but interspecific and intraspecific variation exists in certain parts of the brain. The human cerebellum is smaller than expected for an ape brain of human size. It is suggested that the cerebellum increased less than the cerebrum after the split of the human lineage from the African ancestral hominoid stock. In contrast, humans have a slightly larger temporal lobe and insula than expected, but differences are not statistically significant. Humans do not have a larger frontal lobe than expected for an ape brain of human size and gibbons have a relatively smaller frontal lobe than the rest of the hominoids. Given the fact that the frontal lobe in humans and great apes has similar relative size, it is parsimonious to suggest that the relative size of the whole of the frontal lobe has not changed significantly during hominid evolution in the Plio-Pleistocene.
关于类人猿大脑的主要比较数据稀少，即使在大体水平上，人类和猿类之间主要的神经解剖学差异也尚未得到令人满意的描述。除非对所有现存类人猿物种的大脑进行分析，否则涉及人类大脑进化的基本问题就无法得到充分解决。与原始数据的稀缺形成对比的是，关于人类大脑进化的主题有丰富的文献，并且在大脑特定区域的大小方面存在一些争论，例如额叶。在本研究中，我们对活着的人类、大猩猩和长臂猿受试者应用了一种非侵入性成像技术（磁共振），以研究类人猿大脑的整体大小。图像被重建为三维，获得了大脑及其主要解剖区域的体积估计值，包括额叶和颞叶、脑岛、顶枕区和小脑。类人猿大脑许多大区域的相对大小存在显著的同质性，但在大脑的某些部分存在种间和种内变异。人类小脑比具有人类大小的猿类大脑预期的要小。有人认为，自人类谱系从非洲类人猿祖先种群分离后，小脑的增大程度小于大脑。相比之下，人类的颞叶和脑岛比预期的略大，但差异无统计学意义。人类额叶并不比具有人类大小的猿类大脑预期的更大，而长臂猿的额叶相对比其他类人猿小。鉴于人类和大猩猩的额叶相对大小相似，简约地推测在更新世 - 上新世的人类进化过程中，整个额叶的相对大小没有显著变化。
