人的壽命有上限嗎？新研究指出，沒有上限

一份新的研究激起了一個老生常談的基本生物學話題，也是生命科學領域的一個重要爭議，那就是：人的壽命到底有沒有上限？

這份研究報告發表在《科學》雜志上，意指人的壽命并沒有上限。（《自然》雜志指出，這一發現與其他生物和人口統計學家作類似研究后的發現相矛盾。）

研究團隊考查了大約4000名105歲及以上的高齡意大利人，他們發現在這些“超級年長”的人群中，過了某一節點后死亡風險反而趨于平緩。一般人隨著年紀變大，死亡風險增加，尤其是到了八九十歲。但羅馬大學的伊麗莎貝塔·巴爾比和羅馬第三大學的弗朗西斯科·拉貢納認為，人到了105歲期頤之年后，來年就去世的可能性反而降低至50%。

研究者們強調了其數據的可靠性，并認為他們的“預測擺脫了那些限制早期研究者的人為因素，提供了迄今為止關于超高年齡人群中存在‘ 死亡高原’的最佳證據”。如果高齡后確實存在“死亡高原”，理論上死亡并不必然。

但并不是所有科學家都會達致這樣的結論，比如說紐約阿爾伯特·愛因斯坦醫學院的研究團隊，在分析了世界最高齡人群的年紀后，認定人的壽命的上限是115至125歲。（好奇者可知：有記錄的最長壽的人是法國老婦雅娜·卡爾芒，1997年她去世時，享年122歲。）

阿爾伯特·愛因斯坦醫學院的研究員們在2016年的一份報告中寫道：“通過分析全球人口數據，我們發現在達到100歲高齡后，人的生存能力趨于下降，全球最長壽人士的死亡年齡在90年代以后并沒有提高。我們的研究結果明確顯示，人類的最長壽命是固定的，而且受自然的約束?！保ㄘ敻恢形木W）

譯者：宣峰

New research has revived one of the longest standing, and biologically fundamental, debates in the life sciences: Is there a set limit to how long humans can live?

The study, published in the journal Science, suggests that maybe there isn’t. (It should be noted that this finding contradicts other, similar research by biologists and demographers, as Nature notes.)

Researchers examined a population of nearly 4,000 Italians who were 105 years or older. What they found was that mortality risk essentially plateaus after a certain point for these “super-elderly” individuals. The risk of death increases gradually the older that someone gets, especially as they reach their 80s and 90s. But, say Sapienza University’s Elisabetta Barbi and University of Roma Tre’s Francesco Lagona, after reaching the ripe old age of 105, the odds of dying within the following year essentially drop down to 50%.

The researchers emphasized the quality of their dataset, asserting that their “estimates are free from artifacts of aggregation that limited earlier studies and provide the best evidence to date for the existence of extreme-age mortality plateaus in humans.” If a mortality plateau really does occur at higher ages, that theoretically means death doesn’t have to be an inevitability.

Not all scientists have reached that conclusion. For instance, a team from New York’s Albert Einstein College of Medicine analyzed the ages of the world’s oldest people and pegged the maximum length of human longevity at somewhere between 115 and 125 years. (For the curious: The oldest person ever in recorded history was a French lady named Jeanne Calment, who died at 122 years of age in 1997.)

“[B]y analyzing global demographic data, we show that improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s. Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints,” wrote the Albert Einstein researchers in their 2016 report.