MacLarnon A M, Hewitt G P
School of Life Sciences, Roehampton Institute London, UK.
Am J Phys Anthropol. 1999 Jul;109(3):341-63. doi: 10.1002/(SICI)1096-8644(199907)109:3<341::AID-AJPA5>3.0.CO;2-2.
Many cognitive and physical features must have undergone change for the evolution of fully modern human language. One neglected aspect is the evolution of increased breathing control. Evidence presented herein shows that modern humans and Neanderthals have an expanded thoracic vertebral canal compared with australopithecines and Homo ergaster, who had canals of the same relative size as extant nonhuman primates. Based on previously published analyses, these results demonstrate that there was an increase in thoracic innervation during human evolution. Possible explanations for this increase include postural control for bipedalism, increased difficulty of parturition, respiration for endurance running, an aquatic phase, and choking avoidance. These can all be ruled out, either because of their evolutionary timing, or because they are insufficiently demanding neurologically. The remaining possible functional cause is increased control of breathing for speech. The main muscles involved in the fine control of human speech breathing are the intercostals and a set of abdominal muscles which are all thoracically innervated. Modifications to quiet breathing are essential for modern human speech, enabling the production of long phrases on single expirations punctuated with quick inspirations at meaningful linguistic breaks. Other linguistically important features affected by variation in subglottal air pressure include emphasis of particular sound units, and control of pitch and intonation. Subtle, complex muscle movements, integrated with cognitive factors, are involved. The vocalizations of nonhuman primates involve markedly less respiratory control. Without sophisticated breath control, early hominids would only have been capable of short, unmodulated utterances, like those of extant nonhuman primates. Fine respiratory control, a necessary component for fully modern language, evolved sometime between 1.6 Mya and 100,000 ya.
为了实现完全现代人类语言的进化，许多认知和身体特征肯定都发生了变化。一个被忽视的方面是呼吸控制增强的进化。本文提供的证据表明，与南方古猿和匠人相比，现代人类和尼安德特人的胸椎椎管有所扩大，而南方古猿和匠人胸椎椎管的相对大小与现存非人类灵长类动物相同。根据之前发表的分析，这些结果表明在人类进化过程中胸椎神经支配增加。这种增加的可能解释包括两足行走的姿势控制、分娩难度增加、耐力跑的呼吸、水生阶段以及避免窒息。这些解释都可以被排除，要么是因为它们的进化时间，要么是因为它们对神经系统的要求不够高。剩下的可能功能原因是为了言语而增强呼吸控制。参与人类言语呼吸精细控制的主要肌肉是肋间肌和一组腹部肌肉，它们都由胸部神经支配。对平静呼吸的调整对于现代人类言语至关重要，能够在单次呼气时产生长句子，并在有意义的语言停顿处快速吸气。受声门下气压变化影响的其他语言重要特征包括特定语音单位的强调以及音高和语调的控制。这涉及到与认知因素相结合的微妙、复杂的肌肉运动。非人类灵长类动物的发声明显涉及较少的呼吸控制。没有复杂的呼吸控制，早期原始人类只能发出简短、无调制的话语，就像现存非人类灵长类动物那样。精细的呼吸控制是完全现代语言的必要组成部分，在160万年前至10万年前之间的某个时候进化而来。
