Episode Details

Our very ancient animal ancestors had tails. Why don’t we have them now?

我们非常古老的动物祖先有尾巴。为什么我们现在没有它们？ 

From the time of Charles Darwin, a scientist from the 1800s who studied evolutionary biology, scientists have questioned why and how this happened. 

从 1800 年代研究进化生物学的科学家查尔斯·达尔文 (Charles Darwin) 时代起，科学家们就一直质疑这种现象为何以及如何发生。 

The answer is somewhere around 20 million or 25 million years ago. That was the time apes, the group of animals humans are part of, split from another animal group, monkeys. During that split, our branch of the tree of life lost its tail. 

答案是大约 2000 万或 2500 万年前。那时，猿猴是人类的动物群体，与另一个动物群体猴子分开。在那次分裂中，我们生命之树的树枝失去了尾巴。

Now, scientists have identified at least one of the genetic differences that led to this change. 

现在，科学家们已经确定了至少一个导致这一变化的遗传差异。 

“We found a single mutation in a very important gene,” said Bo Xia. He is a geneticist at the Broad Institute and helped write the study recently released in the publication Nature. 

“我们在一个非常重要的基因中发现了一个突变，”夏波说。他是布罗德研究所的遗传学家，并帮助撰写了最近在《自然》杂志上发表的这项研究。 

The researchers compared the genomes of six kinds of apes, including humans, and 15 kinds of monkeys with tails to find important differences between the groups. Once they identified an important mutation, they tested their theory by using the gene-editing tool CRISPR. They used it to change the same place in embryos of an animal often used in laboratories, mice. Those mice were born without tails. 

研究人员比较了包括人类在内的六种猿类和 15 种有尾巴的猴子的基因组，以发现这些群体之间的重要差异。一旦他们发现了一个重要的突变，他们就使用基因编辑工具 CRISPR 测试了他们的理论。他们用它来改变实验室常用动物——小鼠——胚胎中的同一位置。这些老鼠生来就没有尾巴。