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This is Scientific American's 60-second Science, I'm Eliene Augenbraun.

这里是科学美国人――60秒科学系列，我是艾琳·奥根布劳恩。

How old is your four-legged best friend? Common wisdom says that a dog ages seven years for every human year. But Tina Wang, a graduate student at the University of California, San Diego, wanted a more accurate assessment¹. Her quest started five years ago, when she rescued a dog from a shelter.

你的四条腿最好朋友多大了？普遍认为，狗狗1岁相当于人类7岁。但加州大学圣地亚哥分校的研究生蒂娜·王希望得到更准确地评估狗狗年龄。她的探索始于五年前，当时她从收容所救出了一只狗。

"I kind of just wanted to ask how old she was cause I felt like they were giving me an age that was very sensible, but I wasn't sure she was actually that old. So that kind of started this whole project."

“我想问这只狗多大了，因为他们告诉了我一个合乎情理的年龄，但我并不确定它是否真的那么大。由此开启了整个项目。”

Wang worked in Trey Ideker's lab, where they study changing patterns of DNA² methylation in humans. Small chemical entities³ called methyl groups attach to stretches of DNA, which affects what sequences are active. As we age, some stretches of DNA get more methylated, and others less. The pattern is so consistent over the course of most people's lives that it can be used as an aging "clock." The same process happens in dogs—and published reports existed from other labs about methylation patterns in dogs changing over time.

王在特雷·艾德克的实验室工作，他们在那里研究人类DNA甲基化模式的变化。被称为“甲基原子团”的小化学实体附着在DNA片段上，这会对哪些序列是活跃的产生影响。随着年龄的增长，一些DNA片段的甲基化程度会上升，而另一些则会下降。在大多数人的生命中，这种模式是如此的一致，以至于它可以被看作老化“时钟”。同样的过程也发生在狗狗身上，而且其他实验室也发表了有关狗甲基化模式随时间而变化的报告。

So Wang compared the age-related patterns in 320 humans and 104 Labrador retrievers.

因此，王比较了320个人和104只拉布拉多猎犬的年龄相关模式。

"We knew that DNA methylation can predict age in many mammals, but we didn't know exactly how much of this was shared throughout the progression of life, and it wasn't clear if there was anything that was shared. And b?ecause of these similarities, we were able to identify a conserved⁴ aging signature that allows you to estimate dog years from human years based on this molecular⁵ profile."

“我们知道DNA甲基化可以预测许多哺乳动物的年龄，但并不清楚生命发展过程中DNA甲基化的相同具体程度，也不清楚是否存在相同之处。由于存在这些相似性，我们才能够识别出保守的老化特征，能以这个分子图谱为基础，参照人类的年龄来估算狗狗的年龄。”

The researchers say that dog years per human year change over the lifetime of a dog. For example, their method has a one-year-old dog being the equivalent of a 30-year-old human. A four-year-old dog is about 52. And dog aging per year slows considerably⁶ after that. To see a chart of the aging estimates, check out the paper at the bioRxiv Web site.

研究人员表示，狗狗和人类年龄的换算随狗狗生命时段不同而发生变化。例如，他们的研究方法是让狗狗的1岁相当于人类的30岁。而狗狗的4岁大约相当于人类的52岁。从那以后，狗狗每年的衰老速度会大大减缓。要想查看衰老估计图表，请查看bioRxiv网站上的文章。

For Scientific American's 60-second Science. I'm Eliene Augenbraun.

谢谢大家收听科学美国人——60秒科学。我是艾琳·奥根布劳恩。