唾液会出卖你的年龄
Saliva contains many useful components. Lubricants. Enzymes for breaking down food. And now, compounds that can reveal a person's age. That's according to a study in the journal Public Library of Science ONE. [Sven Bocklandt et al., "Epigenetic Predictor of Age"]
唾液中含有很多有用的化学成分。比如用来降解食物的润滑剂、酶等。而刚刚发现，唾液中还含有能揭示人体年龄的化学成分。这个结论来自于《公共科学图书馆·综合》期刊的一项研究。
During normal development, DNA in your body gets what's called methylated. Small chemicals called methyl groups bind to the DNA, helping to determine which genes become active. But the patterns of methylation change as we grow older. Which was a clue that measuring methylation might give away age.
在正常情况下，人体中的DNA会被甲基化。甲基基团会和DNA结合，帮助确认哪个基因要被激活。但是甲基化的类型会随着人的年龄而改变。这样就提供了一个思路：通过测量甲基化情况或许能揭示年龄的大小。
The researchers studied DNA in saliva contributed by 34 pairs of male identical twins, ages 21 to 55. They found 88 sites on the men's DNA where the amount of methylation correlated with their ages. The scientists next verified that finding in 60 men and women, ages 18 to 70.
研究人员对34对年龄在21到55岁的男性双胞胎所提供的唾液样品里的DNA进行了研究。他们发现男性DNA上88个位点的甲基化程度会随着他们的年龄而变化。科学家之后又在60位年龄在18岁到70岁的男性和女性身上证实了这点。
Then they narrowed in on two genes that had the strongest age-related correlation. And using just that data, they found that they could estimate the ages of their saliva contributors to within five years.
随后，他们将研究范围缩窄至两个与年龄密切相关的基因上。他们发现只用这些数据，就能够估算出唾液提供者的年龄，误差在5岁之内。
This technique might help in crime scene investigations-recovered saliva could tell the age of a perpetrator. So if you're worried about anyone knowing how old you are, be careful where you spit.
这项技术可能有助于犯罪现场调查--获取的唾液能揭示犯罪嫌疑人的年龄。所以，如果你担心有人知道你的年龄，吐唾沫的时候可要小心咯。
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