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How Long Can We Live? 人类可以多长寿？

文/CarlZimmer

译/王丽娟

Since 1900, average life expectancy around theglobe has more than doubled, thanks to better public health, sanitation andfood supplies. But new study of long-lived Italians indicates that we have yetto reach the upper bound of human longevity.

自1900年以来，由于公共卫生、环境卫生和食品供应获得改善，全球人类的平均寿命增加了一倍有余。不过，对长寿的意大利人所做的一项新研究指出，人类尚未达到寿命的上限。

“Ifthere’s a fixed biological limit, we are not close to it,” said ElisabettaBarbi, a demographer at the University of Rome. Barbi and her colleaguespublished their research Thursday in the journal Science.

罗马大学人口统计学家伊莉莎贝塔．巴比说：「如果说有固定生物限制的话，我们还未靠近这个上限。」巴比和她的同事周四（七月十二日）于「科学」杂志发表了他们的研究结果。

The current record for the longest human life spanwas set 21 years ago, when Jeanne Calment, a Frenchwoman, died at the age of122. No one has grown older since — as far as scientists know.

现今人类寿命的最高纪录出现于21年前，这位法国女性珍妮．卡尔蒙122岁时去世。其后，就科学家所知，没有人比她更长寿。

In 2016, a team of scientists at Albert EinsteinCollege of Medicine in the Bronx made the bold claim that Calment was even moreof an outlier than she seemed. They argued that humans have reached a fixedlife span limit, which they estimated to be about 115 years.

2016年，纽约市布朗克斯区「阿尔伯特．爱因斯坦医学院」的一支科学家团队，大胆宣称卡尔蒙是个十分异常的特例。他们说，人类已到达固定寿命的上限，估计这个上限约是115岁。

A number of critics lambasted that research. “Thedata set was very poor, and the statistics were profoundly flawed,” saidSiegfried Hekimi, a biologist at McGill University.

一些批评者对那项研究发出抨击。 麦吉尔大学的生物学家齐格佛里德．希基米说：「数据集很差，统计数字存在严重缺陷。」

Anyone who studies the limits of longevity facestwo major statistical challenges.

任何研究寿命极限的人均面对两大统计上的挑战。

There aren’t very many people who live to advancedages, and people that old often lose track of how long they’ve actually lived.“At these ages, the problem is to make sure the age is real,” Barbi said.

不是很多人能活到高龄，而那么长寿的人通常已记不清楚他们真正的岁数。巴比说：「到了这等年岁，最大问题在于确保年龄的真实性。」

Barbi and her colleagues combed through Italy’srecords to find every citizen who had reached the age of 105 between 2009 and2015. To validate their ages, the researchers tracked down their birthcertificates.

巴比和同事爬梳了意大利的纪录，找出那些在2009到2015年间，年满105岁的所有公民。为了验证他们的年龄，研究人员还追查了他们的出生证明。

The team ended up with a database of 3,836 elderlyItalians. The researchers tracked down death certificates for those who died inthe study period and determined the rate at which various age groups weredying.

该团队最终建立了一个由3,836名意大利老人组成的数据库。这些研究人员追踪了研究期间去世者的死亡证明，并计算出不同年龄组的死亡速度。

It’s long been known that the death rate starts outsomewhat high in infancy and falls during the early years of life. It climbsagain among people in their 30s, finally skyrocketing among those in their 70sand 80s.

人类早已知道，人类的死亡率一开始在婴儿期是稍高，到了幼年时会下降。30几岁时死亡率会再攀升，最后在70几、80几时暴升。

If the death rate kept exponentially climbing inextreme old age, then human life span really would have the sort of limitproposed by the Einstein team in 2016.

倘若死亡率在极端高龄者中呈倍数上升，那么人类寿命可能如爱因斯坦医学院团队在2016年所提，真的已来到那种上限。

But that’s not what Barbi and her colleagues found.Among extremely old Italians, they discovered, the death rate stops rising —the curve abruptly flattens into a plateau.

不过，巴比和她的同事发现情况并非如此。他们发现，在意大利的极端高龄者中，死亡率停止上升，也就是曲线突然变平，变成了高原。

The researchers also found that people who wereborn in later years have a slightly lower mortality rate when they reach 105.

研究人员还发现，较晚出生的人，在他们达到105岁后，死亡率略低。

“Theplateau is sinking over time,” said Kenneth W. Wachter, a demographer at theUniversity of California, Berkeley, who co-authored the new study.“Improvements in mortality extend even to these extreme ages.”

柏克莱加州大学的人口统计学家、这项新研究的共同作者肯尼斯．W．华契特说：「高原随着时间而下降。死亡率的改善甚至延伸到这些极端高龄者。」

“We’renot approaching any maximum life span for humans yet,” he added.

他补充说：「我们还没接近人类的任何最高寿命。」

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