2018年经济学人进化生物学:古人类异血缘交配的证据 (1)（打印版）

Set aside romantic sentiment. Sex is a biological insurance policy.

除了浪漫调情，性也是一份生物保险单。

By chaotically mixing their genetic information, animals generate extraordinary diversity.

通过将基因信息杂乱混合，动物繁衍出了特别的多样性。

In general, the more different the genomes of the partners are,

总的来说，伴侣的基因组差异越大，

the greater the diversity in their offspring and the more likely it is that some of the combinations will survive.

他们后代的多样性越大，这样的杂交结合也越有可能存活下来。

Early humans had no inkling of evolutionary theory.

早期人类并不知晓进化论。

But the discovery of a teenage girl with a Neanderthal mother and a Denisovan father shows they were happily participating in the practice.

但是一位少女（她的母亲是尼安德特人，父亲是丹尼索瓦人）的发现表明早期人类愉快地参与到了进化论的实践中。

A team led by Viviane Slon and Svante Paabo of the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany,

由德国莱比锡城马普进化人类学研究所的维维亚娜·斯隆和斯凡特·派伯领导的团队

carried out genetic analysis on a fragment of bone, more than 50,000 years old, found in a cave in Russia.

对在俄罗斯一处洞穴中发现的五万多年前的一块骨头碎片进行了遗传分析。

It came from a girl, aged about13, who seemed to belong to the Denisovans,

这块骨头碎片来自于一个年纪约13岁的女孩，她似乎是丹尼索瓦人，

a poorly understood cousin of modern humans who evolved in Eurasia around 390,000 years ago

现代人类的表亲，进化于约39万年前的欧亚大陆，

and then were driven into extinction some 40,000 years ago.

然后在约4万年前被迫灭绝，人类对这一族系知之甚少。

An analysis of a Denisovan fossil carried out in 2013 revealed that their genes differed substantially from those of modern-day humans.

2013年对一块丹尼索瓦人化石的分析表明他们的基因和现代人类的基因有着本质上的区别。

Yet what really surprised researchers at the time was the discovery of a little Neanderthal DNA mixed in.

但那时真正让研究人员惊讶的是他们在其中发现了一些尼安德特人的DNA。

Neanderthals are known to have successfully mated with humans

尼安德特人已经和人类进行了成功的交配

because they permanently inserted some of their DNA into the human genome.

因为他们将自己的的一些DNA永久地嵌入到了人类基因组中。

The discovery that the genetically distinct Neanderthals and Denisovans had also reproduced with one another

基因差异明显的尼安德塔人和尼安德特人相结合产生了后代

raised the question of whether their interbreeding had been a regular affair.

这一发现也引出了一个问题：他们这种异血缘交配是常态么。

The results of the new study, published this week in Nature, show that,

本周发表于《自然》杂志上的新研究结果表明

instead of having just a little Neanderthal DNA mixed in with lots of Denisovan DNA,

这个少女的基因中并不仅是少量尼安德塔DNA和大量尼安德特人DNA的掺杂，

the girl's remains contain a much more balanced split: 38.6% of the DNA fragments matched versions of genes

她的遗骸中含有很多其他平衡分裂：在她的DNA碎片中，38.6%显然是属于尼安德特人基因组，

that clearly belong to the Neanderthal genome, and 42.3% to the Denisovan one. There was no clear match for the remainder.

42.3%属于尼安德特基因组。剩下的基因版本尚未得到匹配。