(单词翻译:单击)
听力文本
This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
In Latin America, Native Americans, Africans, and Europeans have intermixed for centuries. So, a few years back, researchers sought to learn more about the ancestry of more than 7,300 people from Brazil, Chile, Colombia, Mexico and Peru. The volunteers provided DNA samples. And they also answered the question: what do you think your background is?
Turns out that what they thought—that is, their predicted ancestry—told a different story than their genes did—with skin color a key factor.
"Their predicted ancestry is actually very well correlated with their skin color, but poorly correlated with their actual genetic ancestry. So that showed us people are actually trying to predict their whole ancestry by just looking at their skin color, which is a pretty crude thing to do, but that's how the attitude is in Latin America." Kaustubh Adhikari, who studies human genetics at University College London.
In particular, lighter-skinned volunteers tended to overestimate their European ancestry whereas darker-skinned subjects overestimated their Native American or African backgrounds.
Now a new study by Adhikari and his colleagues offers a reason for the mismatch. The skin color data and the DNA sequences led the researchers to identify a genetic variant for lighter skin that arose in Asia 20- to 30-thousand years ago. That event appears to be independent of the evolution of lighter skin in Europe.
What's it all mean? Well, light skin color in Latin Americans could still reflect European ancestry. But it could also indicate Native American ancestry—by way of the original Asian immigrants carrying the trait who crossed the temporary Beringia land bridge into what's now Alaska and became the first Americans.
The researchers were also able to show that this gene variant for lighter skin pigmentation is more prevalent in parts of Asia that do not get much sunlight—indicating a possible way this genetic variant could have been selected for. The new study is in the journal Nature Communications.
Adhikari says the findings could help modify Latin Americans' social views. "We know for example there's a big socioeconomic stratification in Latin America, and that correlates, because of the history of colonization, to people's European ancestry. And a proxy of European ancestry is often taken to be light skin color. So what we are trying to show is that such a blind attitude to social aspects is also wrong genetically, that there's also big variation of skin color from the native side that such kinds of simplistic attitudes would be ignoring."
A reminder that ancestry, like so much else, is more than skin deep.
Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.
参考译文
这里是科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。
数个世纪以来，美洲原住民、非洲人和欧洲人在拉丁美洲混合居住。因此，几年前，研究人设法进一步了解来自巴西、智利、哥伦比亚、墨西哥和秘鲁的7300多人的血统。志愿者提供了DNA样本。他们也回答了这个问题：你认为自己的血统背景是什么样的？
结果表明，他们的想法——也就是他们预想的血统——与其基因得出的结果并不一致——这里以肤色为关键因素。
“他们预想的血统实际上与其肤色密切相关，但与他们真正的遗传血统相差甚远。因此，这表明人们实际上是仅看肤色来预测自己的整个血统，这是非常鲁莽的做法，但这就是拉丁美洲人的态度。”在伦敦大学学院研究人类基因的考斯塔布·阿德希卡里说到。
特别是，肤色较浅的志愿者往往会高估自己的欧洲血统，而肤色较深的志愿者则会高估自己的美洲原住民或非洲背景。
现在，阿德希卡里及其同事进行的一项新研究提出了这种错配的原因。依据肤色数据和DNA序列，研究人员找到了一种导致较浅肤色的基因变体，这种变体在2万到3万年前出现。这一事件似乎与欧洲较浅肤色的进化无关。
这是什么意思？拉丁美洲的浅肤色仍能反映出欧洲血统。但其同时也能代表美洲原住民血统——携带这种特征的最初亚洲移民，跨过临时的白令陆桥，进入现在的阿拉斯加，成为第一代美洲人。
研究人员还能证明，这种较浅肤色的基因变异，在日照较少的亚洲地区更为普遍，这表明这种基因变异原本是被选择的可能方式。这项新研究发表在《自然通讯》期刊上。
阿德希卡里说，这项研究有助于修改拉丁美洲人的社会观点。“比如，我们知道拉丁美洲存在巨大的社会经济阶层，基于殖民历史，这一分层与人们的欧洲血统相关。而且欧洲血统的代表通常被认为是浅肤色。因此我们正在试图说明的是，对社会方面的这种盲目态度从基因角度来说也是错误的，原住民在肤色方面发生了巨大的变异，这种简单的观点往往会忽略这一点。”
这提醒我们，血统和其他很多事一样，并不是那么肤浅。
谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。
译文为可可英语翻译，未经授权请勿转载！
重点讲解
重点讲解：
1. correlate with 相互关联；极为相似；
Obesity correlates with increased risk for hypertension and stroke.
肥胖会增加高血压和中风发作的几率。
2. in particular 尤其；特别；
The situation in Ethiopia in particular is worrying.
埃塞俄比亚的局势尤其令人担忧。
3. be independent of 相互独立的；彼此不关联的；
Your questions should be independent of each other.
你的问题应该彼此无关。
4. by way of 采用…方法；通过；
I teach psychology by way of a range of traditional lectures, practicals and tutorials.
我采用传统授课与实践和指导相结合的方式教授心理学。
