人類最長能活多久？

On Nov. 14, 1978, The New York Times began publishing a new weekly section about health and science. For forty years now, Science Times has offered reporting on everything from climate change to genetics to gravitational waves.

1978年11月14日，《紐約時報》開始刊出一個新的每周健康與科學欄目。四十年來，時報科學版提供了從氣候變化到遺傳再到引力波的各種報道。

In 2003, on the 25th anniversary of the section, reporters offered up their thoughts on the most pressing questions in science. Fifteen years later, the questions have changed. But we’re still curious.

2003年，時值科學版的25周年紀念，記者們提出了他們對最緊迫的科學問題的看法。十五年后，問題發(fā)生了變化。但我們?nèi)匀缓闷妗?/p>

—Michael Mason ——邁克爾·梅森(Michael Mason)

The most common risk factor for serious disease is old age. Heart disease, cancer, stroke, neurological conditions, diabetes — all increase radically with advancing years. And the older a person is, the more likely he or she is to have multiple chronic illnesses.

嚴重疾病最常見的風險因素是高齡。心臟病、癌癥、中風、神經(jīng)系統(tǒng)疾病、糖尿病的風險都隨著年齡增長而急劇增加。一個人年齡越大，他/她就越有可能患上多種慢性疾病。

Some scientists hope one day to treat all of them at once — by targeting aging itself. 有些科學家希望有一天能夠同時治療所有這些疾病——通過針對衰老本身。

Humans aren’t built to last forever. The oldest person on record was Jeanne Calment, a Frenchwoman, who died in 1997 at the age of 122. In 2040, the average life span for people in Spain, projected to pass Japan as the country with the longest-lived citizens, will reach about 86 years.

人類不是永生的。有史以來最長壽的人是法國女性讓娜·卡爾芒(Jeanne Calment)，她于1997年去世，享年122歲。2040年，西班牙人的平均壽命預計將超過日本，成為擁有最長壽公民的國家，人均壽命將達到約86歲。

There is considerable dispute, however, over how long humans might live under optimal circumstances. In 2016, a team of scientists declared the upper limit to be 115 years. But in June, researchers reviewing death rates among elderly Italians suggested that there may be no limit at all.

然而，人類能在最理想的環(huán)境下活多久的問題有相當大的爭議。2016年，一組科學家宣布上限應(yīng)為115歲。但在6月，查看意大利老年人死亡率的研究人員表明，人類壽命可能根本沒有任何限制。

In animal studies over the last few decades, scientists have begun to understand the specific cellular and molecular processes that cause the deteriorations of old age.

在過去幾十年的動物研究中，科學家已經(jīng)開始了解導致老年人身體退化的特定細胞和分子過程。

In an essay in the journal JAMA last month, Tamara Tchkonia and Dr. James L. Kirkland of the Mayo Clinic categorized these processes into four broad groups: chronic inflammation; cell dysfunction; changes in stem cells that make them fail to regenerate tissue; and cellular senescence, the accumulation in tissue of aging cells that accompanies disease.

上個月在《美國醫(yī)學會雜志》(JAMA)上發(fā)表的一篇論文中，梅奧醫(yī)院(Mayo Clinic)的塔瑪拉·奇科尼亞(Tamara Tchkonia)和詹姆斯·L·柯克蘭(James L. Kirkland)博士將這些過程分為四大類：慢性炎癥;細胞功能障礙;干細胞變化使它們無法再生組織;細胞衰老，及與疾病相伴的衰老細胞在組織中積累。

Old cells, researchers have found, secrete proteins, lipids and other substances that increase inflammation and tissue destruction. In one study in mice, researchers showed that transplanting these cells to the knee joints of healthy animals causes disease that looks very much like human osteoarthritis.

研究人員發(fā)現(xiàn)，衰老細胞分泌蛋白質(zhì)、脂質(zhì)和其他增加炎癥和組織破壞的物質(zhì)。在一項針對小鼠的研究中，研究人員顯示，將這些細胞移植到健康動物的膝關(guān)節(jié)會導致看起來非常像人類骨關(guān)節(jié)炎的疾病。

Healthy young people have few of these aging cells, but after age 60, they begin to accumulate, and their increasing quantity correlates with disabilities of old age.

健康的年輕人很少有這樣的細胞，但是在60歲以后，它們開始累積，并且其數(shù)量增加與老年失能相關(guān)。

Could there be any remedy that removes these old cells while leaving young cells? Several are being tested.

是否有什么治療方法可以在留下年輕細胞的同時清除這些衰老細胞?有幾項方法正在測試中。

In one study of mice, old cells have been found susceptible to a combination of two drugs: dasatinib, a cancer drug, and quercetin, a plant flavonoid. They improved cardiac function and exercise capacity in old mice, delayed symptoms of osteoporosis and prolonged healthy old age.

在一項針對小鼠的研究中發(fā)現(xiàn)，衰老細胞對兩種藥物的組合敏感：達沙替尼(一種抗癌藥物)和槲皮素(一種植物類黃酮)。他們改善了老鼠的心臟功能和運動能力，延緩了骨質(zhì)疏松的癥狀，并延長了健康的老年狀態(tài)。

Some drugs already approved for other purposes are being tested as “senolytics,” as the drugs that kill old cells are now called.

一些已被批準用于其他目的的藥物，正在測試作為抗衰老藥(senolytics)的效力——這是目前能殺死衰老細胞的藥物的通稱。

Dr. Nir Barzilai, a professor of medicine at the Albert Einstein School of Medicine, is planning a study of metformin, a drug that has been used for 60 years to treat diabetes and has been shown to be effective against several age-related diseases.

阿爾伯特·愛因斯坦醫(yī)學院(Albert Einstein School of Medicine)醫(yī)學教授尼爾·巴茲萊(Nir Barzilai)博士正計劃對二甲雙胍進行一項研究，二甲雙胍被用于治療糖尿病已有60年的歷史，并已被證明可有效對抗幾種與年齡相關(guān)的疾病.

If drugs can treat aging, is aging itself a disease? No, Dr. Barzilai said. 如果藥物能治療衰老，衰老本身是一種疾病嗎?不是，巴茲萊說。

“Neither I nor the Food and Drug Administration is interested in calling aging a disease. Our study is to show that we can prevent a composite of age-related diseases — cardiovascular, cancer, cognitive — and ultimately affect mortality.”

“我和美國食品和藥物管理局(Food and Drug Administration)都無意稱衰老為一種疾病。我們的研究表明，我們可以預防一系列與年齡相關(guān)的疾病——心血管疾病、癌癥和認知疾病——并最終影響死亡率。”

Another drug candidate involves a coenzyme called nicotinamide adenine dinucleotide, or N.A.D. It functions in cell respiration, moving electrons into the mitochondria where energy is produced.

另一種候選藥物涉及一種名為煙酰胺腺嘌呤二核苷酸或NAD的輔酶。它在細胞呼吸過程中起作用，將電子移動到產(chǎn)生能量的線粒體中。

As people age, levels of N.A.D. decline to the point where it is undetectable in the blood of the elderly.

隨著人們年齡的增長，NAD的水平下降到在老年人血液中無法檢測到的程度。

David A. Sinclair, a professor of genetics at Harvard, is working on methods of replenishing those levels. In studies of yeast, worms, flies and mice, “that replenishing rapidly reverses some aspects of aging,” he said. “And now there are trials underway in humans.”(N.A.D. is already peddled in health food stores, but scientists like Dr. Barzilai say it’s a bad idea to take a nutraceutical to extend life — or even an established medication like metformin — until the clinical data are in.)

哈佛大學(Harvard)遺傳學教授大衛(wèi)·A·辛克萊(David A. Sinclair)正在研究補充這種物質(zhì)水平的辦法。在針對酵母菌、蠕蟲、蒼蠅和小鼠的研究中，“補充NAD能快速逆轉(zhuǎn)衰老的某些方面，”他說。“而現(xiàn)在正在進行人類試驗。”(NAD已經(jīng)在健康食品商店里售賣，但像巴茲萊這樣的科學家說，在得到臨床數(shù)據(jù)之前，服用營養(yǎng)食品延長生命——甚至是二甲雙胍等早已投入使用的藥物——是一個壞主意。)

One widely published researcher in the field, S. Jay Olshansky, a professor of epidemiology at the University of Illinois at Chicago, said that there is an upper limit to how long we can live — about 85 years.

伊利諾伊大學芝加哥分校(University of Illinois at Chicago)流行病學教授S.杰伊·奧爾沙恩斯基(S. Jay Olshansky)是在該領(lǐng)域發(fā)表了諸多論文的研究者，他說我們能活多久有一個上限——大約85年。

“Parts of the body, including the brain, are not designed for long-term use,” he said. “We’re seeing the consequences of pushing the limits of survival: the rise of Alzheimer’s disease, dementias, joint and hip problems, loss of muscle mass.”

“身體的某些部位，包括大腦，不是為了長期使用而設(shè)計的，”他說。“我們正在看到推動生存極限的后果：阿爾茨海默病、失智癥、關(guān)節(jié)和髖關(guān)節(jié)問題的增加、肌肉質(zhì)量的減少。”

“These are not a consequence of failure, but of success,” he added. Dr. Olshansky advocates extending “health span, not life span.”

“這些不是失敗的結(jié)果，而是成功的結(jié)果，”他補充道。奧爾沙恩斯基主張延長“健康跨度，而非生命跨度”。

We will all die. No serious scientist believes in immortality. But we also are closer to assuring healthier old age than ever before.

我們都會死。嚴肅的科學家是不相信永生的。但與此同時，我們距離有保障的健康晚年也更近了一步。

“There are dozens of companies in clinical trials, or planning them, tackling all the different causes of aging,” Dr. Sinclair said. “I’m optimistic that there will be a few successes in the coming years.”

“有許多公司正在進行或計劃臨床試驗，阻斷所有不同的衰老原因，”辛克萊說。“我很樂觀，未來幾年會取得一些成功。”