Hypoglossal Canal Size in Living Hominoids and the Evolution of Human Speech
Hypoglossal Canal Size in Living Hominoids and the Evolution of Human Speech
复制标题
现存类人猿舌下管的大小与人类语言的进化
DOI：
10.1353/hub.2003.0057
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
M. Cartmill
中科院分区：
文献类型：
--
作者：
W. Jungers;Amy Pokempner;R. F. Kay;M. Cartmill
舌下管的相对大小已被提出作为鉴定类人猿化石记录中类似人类语言能力的有用诊断工具。在人类中观察到相对较大的舌下管（按口腔大小标准化），并假定与相对较大的舌下神经相对应，舌下神经是控制舌头运动功能的颅神经。结果表明，人类舌头运动神经支配模式和相关的言语电位与非洲猿和南方古猿有很大的不同；现代人类的状况显然出现在中更新世人的时代。1999年对灵长类动物舌下管大小进行的一项更广泛的种间分析拒绝了这种诊断和基于它的推论。为了解决这些意见分歧，我们认为这些分歧部分是基于有偏见的尺寸调整和/或没有根据的假设，我们从298个现存的人猿头骨中收集并分析了一组新的数据，包括猩猩、大猩猩、黑猩猩、倭黑猩猩、暹罗猿、长臂猿和现代人。舌下神经本身的绝对大小数据也从人类和黑猩猩尸体的小样本中收集到。计算舌下管相对大小（RHCS）无标度指数为100 8（舌下管面积0.5/口腔体积0.333）。在所有现存的类人猿物种中，舌下管没有发现明显的性别二态性，但舌下管的绝对和相对大小在种间存在显著差异。从绝对意义上说，人类的运河比除大猩猩以外的任何其他物种都要大得多，但与黑猩猩有相当大的重叠。人类也具有较大的RHCS值，但长臂猿具有更大的该指数的平均平均值；黑猩猩和倭黑猩猩的RHCS与人类有明显的重叠。南方古猿阿法种的RHCS值完全在人类和长臂猿的范围内，为化石人的选定代表计算的指数也是如此。此外，舌下神经本身的大小，以每毫米长度的神经质量来表示，并不能将黑猩猩与现代人类区分开来。因此，我们得出结论，舌下管的相对大小既不可靠，也不能充分预测类人语言能力，古人类学仍然缺乏一个可量化的形态学诊断，以确定这种能力最终在人类职业生涯中出现的时间。
The relative size of the hypoglossal canal has been proposed as a useful diagnostic tool for the identification of human-like speech capabilities in the hominid fossil record. Relatively large hypoglossal canals (standardized to oral cavity size) were observed in humans and assumed to correspond to relatively large hypoglossal nerves, the cranial nerve that controls motor function of the tongue. It was suggested that the human pattern of tongue motor innervation and associated speech potential are very different from those of African apes and australopithecines; the modern human condition apparently appeared by the time of Middle Pleistocene Homo. A broader interspecific analysis of hypoglossal canal size in primates conducted in 1999 has rejected this diagnostic and inferences based upon it. In an attempt to resolve these differences of opinion, which we believe are based in part on biased size-adjustments and/or unwarranted assumptions, a new data set was collected and analyzed from 298 extant hominoid skulls, including orangutans, gorillas, chimpanzees, bonobos, siamang, gibbons, and modern humans. Data on the absolute size of the hypoglossal nerve itself were also gathered from a small sample of humans and chimpanzee cadavers. A scale-free index of relative hypoglossal canal size (RHCS) was computed as 100 8 (hypoglossal canal area0.5/oral cavity volume0.333). No significant sexual dimorphism in RHCS was discovered in any species of living hominoid, but there are significant interspecific differences in both absolute and relative sizes of the hypoglossal canal. In absolute terms, humans possess significantly larger canals than any other species except gorillas, but there is considerable overlap with chimpanzees. Humans are also characterized by large values of RHCS, but gibbons possess an even larger average mean for this index; siamang and bonobos overlap appreciably with humans in RHCS. The value of RHCS in Australopithecus afarensis is well within both human and gibbon ranges, as are the indices computed for selected representatives of fossil Homo. Furthermore, the size of the hypoglossal nerve itself, expressed as the mass of nerve per millimeter of length, does not distinguish chimpanzees from modern humans. We conclude, therefore, that the relative size of the hypoglossal canal is neither a reliable nor sufficient predictor of human-like speech capabilities, and paleoanthropology still lacks a quantifiable, morphological diagnostic for when this capability finally emerged in the human career.