Holloway R L
Hum Neurobiol. 1983;2(3):105-14.
The paleoneurological evidence for human language origins and other cognitive activities is tantalizing, but uncertain given the often incomplete, fragmented, and eroded cranial portions of our fossil ancestors. Nevertheless, both the Taung and A.L. 162-28 endocranial portions, attributed to the earliest-known hominids (i.e. Australopithecus afarensis and africanus) evidence some cerebral organization beyond a typical pongid pattern, in that there appears to be a reduction in primary visual striate cortex, and thereby a relative increase in posterior and inferior parietal cortex. At 1.8-2.0 million years, there is clear fossil evidence for a Homo lineage showing a more modern and enlarged third inferior frontal convolution, expanded brain size (e.g., 750+ ml), and strong cerebral asymmetries identical to those known for modern Homo sapiens. Additional evidence of sexual dimorphism in the modern human corpus callosum, in which the posterior splenial portion is larger in females, taken in conjunction with known clinical and psychological evidence relating to cognitive task specialization, suggests that this dimorphism represents a biological heritage from past selection pressures for a dichotomous but complemental social behavioral set of adaptations to favor a division of sexual labors compatible with nurturing offspring with delayed maturation, prolonged growth, and a longer period of postnatal neural plasticity.
关于人类语言起源和其他认知活动的古神经学证据很诱人，但鉴于我们化石祖先的颅骨部分往往不完整、破碎且受到侵蚀，所以并不确定。尽管如此，被认为属于已知最早的原始人类（即阿法南方古猿和非洲南方古猿）的汤恩和A.L. 162 - 28的颅内部分，显示出一些超出典型猿类模式的大脑组织特征，即初级视纹状皮层似乎有所减少，从而顶叶后部和下部相对增加。在180万至200万年前，有明确的化石证据表明人属谱系呈现出更现代且增大的额下回第三回、脑容量扩大（例如750毫升以上）以及与现代智人相同的强烈脑不对称性。现代人类胼胝体存在性别二态性的额外证据，即女性的胼胝体后部较大，结合已知的与认知任务专业化相关的临床和心理学证据，表明这种二态性代表了过去选择压力下的一种生物遗传，是为了适应二分但互补的社会行为模式，以利于与养育成熟延迟、生长延长和产后神经可塑性较长的后代相适应的性别分工。
