南京直立人的高耸鼻梁和气候适应

Strongly Projecting Nasal Bones and Climatic Adaptation of Nanjing Homo erectus

为论证南京直立人高耸的鼻梁是对气候的适应,本文检验了有关鼻骨的3种测量项目;结果表明:鼻尖指数和鼻根指数用来表达整个骨性鼻梁的外突程度是有价值的,但眶间宽高指数不能用来说明整个鼻梁外突程度。Carey和Steegmann氏著作中的各人群鼻尖指数和鼻根指数数据和相应的气候资料表明,干燥地区人群的鼻比潮湿地区的要较外突,寒冷地区人群的鼻要比温暖地区的较外突。这种鼻的外突程度与干、寒气候的关系可以从人鼻的解剖学和呼吸生理学方面得到支持。因纽特人(爱斯基摩人)虽然鼻梁并未达到高耸级别,但有因上颌窦缩小而明显扩大的鼻腔,大的鼻甲、鼻道等。因此,因纽特人的鼻形态代表鼻对寒冷气候适应的另一种方式,不能用作证据来否认鼻梁高耸与气候之间的关系。另外,对南京直立人化石地点的孢子花粉、植硅体的研究表明,南京直立人是生活在冰期环境中,当时的冰期在很大程度上可以与冰期盛期或大冰期相对比。综上所述,南京直立人鼻梁高耸是对寒冷气候适应的结果,未必是由于基因交流的结果;这是对南京直立人鼻梁高耸的成因的目前一个最合理的解释。

In order to argue that Nanjing Homo erectus is a cold-adapted species, the measurements of three kinds are examined. Results show that the rhinal and simotic indices are valuable but that the dacryon index is unsuitable for measuring the projection of nasal bones. The rhinal and simotic indices and climatic data in the paper by Carey and Steegmann＇s paper suggest that ＂ … the human nose projects more in drier areas than in humid ones, and more in cold climates than in warm ones.＂ This staterment is also supported by nasal anatomy and respiratory physiology. In the Inuit people, there is a possibility of a highly efficient ＂air-conditioning＂ system, even though their nasal bones are not strongly projected. ＂This system would be characterized by restricted aperture width, but an appreciably expanded internal nasal chamber, with enlarged conchae, meatuses, etc. ＂ The nasal morphology of the Inuit represents another type of nasal climatic adaptation, and cannot be used as proof to contradict the relationship between strongly projecting nasal bones and climatic adaptation. Moreover, pollen, spores and phytoliths from cave deposits indicate a cold glacial environment, which is comparable to that of a major ice age. To summarize, it is the most reasonable explanation so far that the strongly projecting nasal bones of Nanjing Homo erectus are the product of climatic adaptation rather than of gene flow.