Mitochondrial DNA is passed intact from mother to offspring. 线粒体DNA会原封不动地由母亲遗传给后代。 It is not involved in sexual mixing, so it changes only by the random process of mutation. 它不参与有性生殖中的基因重组，所以只有在随机突变中才会发生变化。 The lack of mutations that might have distinguished the DNA of the individuals in question from each other suggests not only a common ancestor, but a relatively recent one. 文中提到的两个个体的DNA不存在能够将彼此区分开来的突变，这不仅表明他们有共同的祖先，而且说明这个共同祖先存在的时间并不十分久远。 Further analysis showed also that two of the mitochondrial DNA samples from Chagyrskaya were closer to the Okladnikov boy than to any of the other Chagyrskayans. 通过进一步的分析，Chagyrskaya洞穴两个个体的线粒体DNA样本表明，这两个个体与Okladnikov洞穴男孩的亲缘关系，比他们和同洞穴其他个体的关系都要近。 And when the team looked at data on y-chromosomes, which pass intact from father to son, as well as their mitochondrial data, they were able to draw some tentative conclusions about Neanderthal communities. 研究小组研究了由父亲传给儿子的y染色体的数据，以及样本中线粒体的数据，得出了一些关于尼安德特人群体的初步结论。 If members of a populationmate more or less at random with those of the opposite sex, the so-called coalescence time - how far in the past their most recent common ancestor lived - should be the same for mitochondrial (matrilineal) and y-chromosome (patrilineal) DNA. 如果一个种群的成员在某种程度上随机与异性进行交配，那么线粒体(在母系中传递)DNA和y染色体(在父系中传递)DNA的所谓“溯祖时间”，即种群成员最后一个共同祖先出现距今的这段时间，应该是相同的。 The researchers found, however, that the average coalescence time for the y-chromosome was 500 years, while that for the mitochondrial genome was around 5,000 years. 然而，研究人员发现，y染色体的平均溯祖时间为500年，而线粒体基因组的平均溯祖时间约为5000年。 To explain this order-of-magnitude difference, they modelled various possibilities. 为了解释这种数量级的差异，研究人员对各种可能性进行了模拟。 The one which best fitted the data was that the Neanderthals of the Altai lived in groups of around 20 individuals, with at least 60% of the females in a group having migrated there from elsewhere. 最符合数据结果的情况是，居住在阿尔泰山的尼安德特人组成了很多大约20个人的群体，其中至少有60%的女性是从其他地方迁徙到那里的。 The size of such groups is similar to that deduced for Palaeolithic bands of Homo sapiens, which probably had around 25 members. 群体的大小与推断得到的旧石器时代大约由25人组成的智人群体类似。 When dealing with humanity's ancestors and cousins it is easy and tempting to over-interpret the scarce data available - and practitioners of the subject have indeed been guilty of doing this in the past. 在研究人类的祖先和近亲的课题时，人们很容易过度解读现有的稀有数据——而这一课题的研究者过去确实犯过这样的错误。 So these conclusions should be treated with care. 因此，我们应该更加谨慎地对待这些结论。 But if nothing else, this study shows that the methods which brought Dr. Paabo his prize have increased the pool of data available for such speculations in an extraordinary way. 但至少，这项研究表明，让佩博博士获得诺贝尔奖的研究方法，以一种非同寻常的方式扩充了可用于此类研究推测的数据库。
