最新一期英国《自然》杂志刊登研究报告说，对俄罗斯西伯利亚一个山洞里发现的古人类化石进行基因检测显示，它不同于现代人和任何已知的古人种，很可能是一种前所未知的古人种。
报告说，俄罗斯研究人员早在2008年就在该山洞中发掘出这块指骨化石，但起初认为它是已研究较多的古人种尼安德特人留下的。后来，这块化石被送到德国进行基因检测，对其线粒体DNA的分析结果显示，它不属于现代人和任何已知的古人种。
尼安德特人生活在大约12万年到3万年前。据介绍，在线粒体DNA对比上，尼安德特人与现代人有202处差异，而这块化石与现代人有385处差异，研究人员因此推断它所属人种的生存年代比尼安德特人更早，应该大约在100万年前。
有专家认为，单凭线粒体DNA还不能确认这就是一种未知的古人种。为此，研究人员尚未为其命名，且计划对这块化石进行基因组测序。如果完整基因组测序显示它真属于一个未知的古人种，这将是首次通过基因手段确认人种，也将是迄今完成的对最古老人类的基因组测序。
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《自然》发表论文摘要（英文）
Nature advance online publication 24 March 2010 | doi:10.1038/nature08976; Received 21 January 2010; Accepted 3 March 2010; Published online 24 March 2010
The complete mitochondrial DNA genome of an unknown hominin from southern Siberia
Johannes Krause1, Qiaomei Fu1, Jeffrey M. Good2, Bence Viola1,3, Michael V. Shunkov4, Anatoli P. Derevianko4 " Svante Pääbo1
Top of pageWith the exception of Neanderthals, from which DNA sequences of numerous individuals have now been determined1, the number and genetic relationships of other hominin lineages are largely unknown. Here we report a complete mitochondrial (mt) DNA sequence retrieved from a bone excavated in 2008 in Denisova Cave in the Altai Mountains in southern Siberia. It represents a hitherto unknown type of hominin mtDNA that shares a common ancestor with anatomically modern human and Neanderthal mtDNAs about 1.0 million years ago. This indicates that it derives from a hominin migration out of Africa distinct from that of the ancestors of Neanderthals and of modern humans. The stratigraphy of the cave where the bone was found suggests that the Denisova hominin lived close in time and space with Neanderthals as well as with modern humans2, 3, 4.
