中国古人类颅内模及脑演化研究进展

Progress in endocast and human brain evolution of Chinese human fossils

颅内模保存有脑表面的形态结构,是脑演化研究的直接证据。中国最早复原和研究的颅内模来自20世纪20年代北京周口店遗址发现的3号猿人头骨;此后虽然中国境内也相继发现了一些古人类的头骨化石,但由于古人类标本非常珍贵,不允许对其进行实体解剖,加上多数头骨破碎或者内部附有地层胶结物,导致颅内模无法成功复原。受技术水平及研究手段的限制,研究者一般只是侧重于化石外表形态结构的研究。高分辨率工业CT和3D软件的应用,可以在不损坏标本的情况下,虚拟复原出化石的内部解剖结构,使得一些重要的古人类化石标本的颅内模被复原出来,促进了脑演化的研究。近年来,本文第一作者采用新技术、新方法复原了南京直立人、柳江人等一些重要的中国古人类头骨的颅内模,通过对其颅容量、脑沟回特征、脑不对称性、脑表面的动、静脉血管压迹、各脑叶的大小、形状及比例的研究,获取了中国古人类脑形态特征变化的数据,为探讨东亚地区古人类的演化提供了参考信息。

Ancient human skull endocasts, known as endocranial casts, preserve surface information of brain morphologies, so they represent direct evidence in the study of human brain evolution. The ZKD Skull III, unearthed from the Peking Man site at Zhoukoudian, Beijing, in the 1920s was the first endocast to be reconstructed and studied in China. Since that time, other human skull fossils collected across China have been studied with regard to fossil appearance and morphological structure, resulting in the reporting of a few endocast studies. The underlying reasons for this lack of endocast studies are for a number of reasons. Ancient human specimens are so precious that destructive analyses are not warranted; broken skulls or intra-skull stratum cement preclude reconstruction of informative endocasts; and technology and research methodologies require further development in order to yield useful data. Recently, the application of high resolution industrial CT and 3D imaging technologies can help researchers virtually to reconstruct internal anatomical structures of skull fossils without damaging fossil specimens. Using these cutting-edge methodologies, the first author has reconstructed endocasts of several ancient human skulls unearthed in China, including Nanjing Homo erectus, Liujiang Man, and so on. Data derived from these studies have permitted us to demonstrate changes in cerebral morphological characteristics of ancient humans in China throughout the course of human evolution. Specifically, by exploring cranial capacity, gyrus features, brain asymmetry, and brain surface impressions of arterial and venous blood vessels, as well as brain sizes, shapes, and lobe proportions, morphological changes of the ancient human brain can be visualized across time. Thus, endocasts of important ancient human fossil specimens have furthered our understanding of brain evolution. This work should serve as a foundation for future evolutionary studies of ancient humans in East Asia.