14

A Study of the origins and distribution of human populations used to be based on archaeological and fossil evidence. A 以前，人类起源及分存的研究是以考古学和化石为基础的。 A number of techniques developed since the 1950s, however, have placed the study of these subjects on a sounder and more objective footing. 然而，自 20 世纪 50 年代起，许多技术得以发展，对于这些课题的研究已建立在更为客观的基础上。 The best information on early population movements is now being obtained from the ' archaeology of the living body', the clues to be found in genetic material. 遗传资料中发现的线索显示，“活体考古学”现在已得到关于早期人类迁移的最好消息。

15

B Recent work on the problem of when people first entered the Americas is an example of the value of these new techniques. B 近期关于人类何时首先进入美洲的问题研究，就是这些新技术价值的例子。 North-east Asia and Siberia have long been accepted as the launching ground for the first human colonizers of the New World. 东北亚和西伯利亚长期以来被认为是“新世界”人类移民最先登陆的地方。 But was there one major wave of migration across the Bering Strait into the Americas, or several? 但是，从白令海峡穿越至美洲的移民浪潮是一支吗？还是有几支？ And when did this event, or events, take place？ 这一或这些事件发生在什么时候？ In recent years, new clues have come from research into genetics, including the distribution of genetic markers in modern Native Americans. 近些年，遗传学的研究获得新线索，包括现代本地美国人的遗传标记分布。

16

C An important project, led by the biological anthropologist Robert Williams, focused on the variants (called Gm allotypes) of one particular protein - immunoglobin G- found in the fluid portion of human blood. C 由 Robert Williams 领导的重要项目集中于特定蛋白质的变体（GM 异型抗免疫球蛋白）研究，这一特定蛋白质，即 GM 异型抗免疫球蛋白，从人体血液部分发现， All proteins 'drift', or produce variants, over the generations, and members of an interbreeding human population will share a set of such variants. 所有蛋白质都“漂流”或制造变体，会跨越几代人，一些相互交配的人类成员间会分享一套变体。 Thus, by comparing the Gm allotypes of two different populations (e.g. two Indian tribes), one can establish their genetic 'distance', which itself can be calibrated to give an indication of the length of time since these populations last interbred. 因此，通过比较两个不同群体间（如两个印第安部落）的 GM 异型抗免疫球蛋白就可以建立起他们的遗传“距离”，这一距离可被测量，以此显示出这些群体最后相互交配至今的时间跨度。

17

D Williams and his colleagues sampled the blood of over 5,000 American Indians in western North America during a twenty- year period. D 在 20 年间，Williams 和他的同事，对西北美洲的 5000 名美国印第安人进行采样。 They found that their Gm allotypes could be divided into two groups, one of which also corresponded to the genetic typing of Central and South American Indians. 研究发现他们的 GM 异型抗免疫球蛋白可分为两组，其中一组与中部及南部美国印第安人的遗传类型吻合。 Other tests showed that the Inuit (or Eskimo) and Aleut formed a third group. 其他试验表明，因纽特人（或爱斯基摩人）及阿申留人构成第三组。 From this evidence it was deduced that there had been three major waves of migration across the Bering Strait. 由这些证据可推论出，穿越白令海峡的是三个主要移民波。 The first, Paleo-lndian, wave more than 15,000 years ago was ancestral to all Central and South American Indians. 第一波是印第安人祖先，于 15,000 年前迁移，是所有中部及南部美国印第安人的祖先。 The second wave, about 14,000-12,000 years ago, brought Na-Dene hunters, ancestors of the Navajo and Apache (who only migrated south from Canada about 600 or 700 years ago). 第二波是在约 14,000—12,000 年前，带有纳丁猎手·纳瓦霍人和阿帕奇的祖先（仅在 600 年或700 年前从加拿大迁移至南部）。 The third wave, perhaps 10,000 or 9,000 years ago, saw the migration from North-east Asia of groups ancestral to the modern Eskimo and Aleut. 第三波或许在 10,000 年或 9,000 年前，东北亚的迁移祖先群发展成了现代爱斯基摩人和阿申留人。

18

E How far does other research support these conclusions ？ E 其他研究支持这些结论吗？ Geneticist Douglas Wallace has studied mitochondrial DNA in blood samples from three widely separated Native American groups: Pima- Papago Indians in Arizona, Maya Indians on the Yucatan peninsula, Mexico, and Ticuna Indians in the Upper Amazon region of Brazil. 遗传学家 Wallace 研究了三大主要独立的本地美国群体血液样本的线粒体 DNA，即位于亚利桑那州的皮比马帕格印第安人，位于尤卡坦半岛的玛亚印第安人、墨西哥人及位于巴西亚马逊河上游的悌卡纳印第安人。 As would have been predicted by Robert Williams's work, all three groups appear to be descended from the same ancestral (Paleo-lndian) population. 正如 Robert Williams著作所预示的那样，这三个群体似乎全部都有一个祖先群体（帕莱奥印第安人）。

19

F There are two other kinds of research that have thrown some light on the origins of the Native American population; they involve the study of teeth and of languages. F另外有两项研究已找到了本地美洲人群的起源曙光，包括对牙齿及语言的研究。 The biological anthropologist Christy Turner is an expert in the analysis of changing physical characteristics in human teeth. 生物考古学家 Chrity Turner 是一名分析人类牙齿物理特性变化方面的专家。 He argues that tooth crowns and roots have a high genetic component, minimally affected by environmental and other factors. 他认为，牙冠和牙根具有很高的遗传成分，很少受到环境及其他因素的影响。 Studies carried out by Turner of many thousands of New and Old World specimens, both ancient and modern, suggest that the majority of prehistoric Americans are linked to Northern Asian populations by crown and root traits such as incisor shoveling (a scooping out on one or both surfaces of the tooth), single-rooted upper first premolars and triple-rooted lower first molars. Turner 通过对几千名从古至今的世界新旧案例的研究揭示出，史前美洲人与北亚人在牙冠和牙根方面息息相关，如门齿及锄齿（即一种表面的一面或两面带有锄铲状的牙齿），单根的上部前臼齿及三根下部前臼齿。

According to Turner, this ties in with the idea of a single Paleo-lndian migration out of North Asia, which he sets at before 14,000 years ago by calibrating rates of dental micro-evolution. 据Turner 所言，这与北亚迁移的一支 14,000 年前的帕利奥印第安人相关，他通过校准牙齿微进化比率得出的。 Tooth analyses also suggest that there were two later migrations of Na-Denes and Eskimo- Aleut. 牙齿分析也提出，之后有两支移民就是纳丁人和爱斯基摩 - 阿申留人。

G The linguist Joseph Greenberg has, since the 1950s, argued that all Native American languages belong to a single 'Amerind' family, except for Na-Dene and Eskimo-Aleut - a view that gives credence to the idea of three main migrations. G 从 20 世纪 50 年代开始，语言学家 Joseph Greenberg 认为本地美洲语言属于单一Amerind 语系，除纳丁和爱斯基摩 - 阿申留人以外——这一观点充分支持了三支移民的观点。 Greenberg is in a minority among fellow linguists, most of whom favour the notion of a great many waves of migration to account for the more than 1,000 languages spoken at one time by American Indians. 但在语言学家中，Greenberg 仍处于少数之中。大多语言学家仍赞成数支移民主移民的观点，以解释美洲印第安同期并存 1,000 多种语言的原因。 But there is no doubt that the new genetic and dental evidence provides strong backing for Greenberg's view. 但是，毫无疑问，最新遗传和牙齿强烈地佐证了 Greenberg 的观点。 Dates given for the migrations should nevertheless be treated with caution, except where supported by hard archaeological evidence. 然而，尽管如此，仍须谨慎对待移民的时期问题，除非得到考古铁证的支持。