再论南京直立人高鼻梁的成因

Further Discussion on the Factor Causing the Highly Protruding Nasal Saddle of Homo Erectus from Nanjing

本文以周口店、南京、Atapuerca SH5、Petralona、Arago、Bodo、Kabwe的中更新世人类化石举例显示,在类似的环境中鼻梁高耸的程度可以不同,不同凉热可以有相似高耸的鼻梁,从而对南京直立人的高鼻梁不是由于对寒冷气候的适应的论点提出补充论证。在这样的情况下,自然应该考虑南京直立人鼻梁高耸的原因在于遗传的因素。本文试图探讨南京高耸鼻梁可能的基因来源,首先论证在中国化石人类中罕见高耸的鼻梁,更没有比南京更早的高耸鼻梁,而非洲和欧洲中更新世多见高耸鼻梁,这种状态在欧洲延续至今,而且非洲已经发现60万年前的比南京早的高耸鼻梁。最后讨论南京直立人的时代和与非洲、欧洲相距遥远的地理位置都不能否定本文的推论。

A comparison on the faunae from Nanjing and at Zhoukoudian Homo erectus sites indicates similarity between the paleo-climate of them, but the nasal profile of Homo erectus from Nanjing is protruding while that of Zhoukoudian is flat. The florae of Zhoukoudian, Gran Dolina and Galeria of Atapuerca are somewhat similar in having some common plants such as Quercus, Pinus, Cupressaceae, Betula, Juglans, Ulmus, Carpinus, while the nasal profile of human fossils from Zhoukoudian and Sima de los Huesos of Atapuerca are quite different in the degree of protruding. So both protruding and flat nasal profiles could be seen in the environments with similar paleo-temperatures. The paleo-climate for Quyuan River Mouth hominid is warm, if the nasal profile of skull E9002 is originally protruding before being deformed, it refutes the view that protruding profile of Nanjing Homo erectus is caused by cold environment. Bodo and Kabwe skulls are yielded from the tropical zone, that of Petralona and Arago are from the temperate zone, and they all have similarly protruding nasal saddle, this fact is unfavorable to the notion that the protruding nasal saddle is caused by cold climate. Coon（ 1962,534）presented the measuring data of the infraorbital foramen of Greenland Eskimo, La Ferrassie 1, La Chapelle and modern Europeans. He wrote that the Eskimos and Neanderthal ＂keep their faces from freezing in part by a relatively great blood flow as indicated by the large bore of the infraorbital foramen＂ while modern Europeans have much smaller infraorbital foramens with a diameter around 3ram. The Homo erectus from Nanjing has only a single infraorbital foramen also with 3ram in diameter. This strengthens the notion that facial morpgology of Nanjing Homo erectus is not resulted from cold adaptation. Based on the above mentioned evidence and the paper published in Number 4 of last volume of this journal, the present author believes that the protruding nasal profile of Homo erectus from Nanjing is unlikely produced by adaptation to cold paleo-environment, another alternative should be considered. The nasal profile of most of human fossils in China and other parts of Eastern part of Asia is flat, while that in Europe is more protruding. It is probable that the degree of protruding of the nasal saddle is one of the characters which distinguish the human lineage of East Asia from that of Europe. If Bodo and Atapuerca SH are within an evolutionary lineage and the protruding nasal profile of the latter could be inherited from the Bodo population, why not the protruding nasal profile of Nanjing could be derived also from Bodo population？ In 1998 the present author proposed an hypothesis, Continuity with Hybridization, for the human evolution in China. The present article together with the article published in 4^th issue of last volume of this journal, provides new evidence for this hypothesis in addition to those shown in other Middle Pleistocene fossils,such as the rounded orbit and its sharp infero-lateral margin in Maba cranium as well as the paranasal bulge in Dali skull which are rarely seen in China and are frequently shown in the Middle Pleistocene fossils in Europe and Africa.