To us humans,aging seems inevitable-probably because no human has ever not aged.But getting older isn't as universal a fact of life as we might think.Take the naked mole rat.Unlike their less naked brethren,they don't appear to age after reaching adulthood-years pass,but the rats don't get weaker,more susceptible to disease,or wrinkly...at least not any more wrinkly...and they keep on making as many babies as ever.
人都会变老 可能是因为没有长成大的人。不过 与我们想象的不同 变老并非生命常态。就拿裸鼹鼠煮个栗子。与不太暴露的表亲不同，裸鼹鼠成年后似乎不会变老 鼹鼠不会一年一年地衰弱 易得病 或是变皱...至少没皱得厉害...并仍在不断繁衍后代.
Surprisingly,they aren't any more likely to die in old age than when they're young adults.It's as if they've found the fountain of youth,though perhaps not the fountain of beauty.And naked mole rats aren't alone in not aging:rockfish,lobsters,and bristlecone pines also seem to stay forever young...or at least forever middle-aged.
另外 年长鼹鼠不比年轻的更容易死亡。它们好似发现了青春源泉，不过泉水里美貌的含量为零。不会变老的不只有裸鼹鼠：岩鱼 龙虾和狐尾松都能永葆青春...要么拥永葆中年。
We're not exactly sure how these species do it,but their anti-aging secret may have to do with their ability to rebuild the DNA caps on their chromosomes.These caps,called telomeres,are one line of defense against aging in many species.That's because cells need to divide to replace old or dysfunctional cells,but each time they replicate,they lose a little bit of DNA from the end of each chromosome.
我们尚不完全确定它们怎么做到的，不过 不老秘诀可能与 它们重建染色体的DNA帽的能力有关这些帽子叫“端粒” 是许多物种抵御衰老的一道防线。由于细胞需要通过分裂 替换旧有或异常细胞，但每次复制时，染色体末端都会损失一点DNA。
Normally that doesn't matter,since these lost bits come from the telomere end caps that don't encode important imformation.But after many replications,the telomeres get trimmed so short that the cells can't afford to lose any more DNA,and they stop replicating.Age-defying species like naked mole rats,however,pump out high levels of a telomere-rebuilding enzyme that enables them to keep on replacing old and dysfunctional cells indefinitely.
这一般没什么事，因为端粒上损失的部分不存储重要信息。不过 多次复制后 端粒越来越短 细胞无法损失更多DNA 因而停止复制。而裸鼹鼠这些不老物种，会产生大量的端粒重建酶 使其得以不断替换旧有或异常的细胞.
A few kinds of human cells make this enzyme,but the vast majority don't.And even if we could trick the rest into producing it,then we'd have another problem:more replications means more chances for mutations that could turn a cell cancerous.Naked mole rats don't care because they seem to be immune to cancer;but we humans certainly aren't.
人类有少数细胞也可以 但大多数不行。即便能诱使其他细胞产生酶 也会引发新的问题：复制越多 变异可能性越大 细胞便会癌变。不会得癌症的裸鼹鼠表示毫无压力;然而人类亚历山大。
However,as amazing as naked mole rats are,they can only pause their aging-the tiny jellyfish Turritopsis dohrnii can age in reverse.Like butterflies,Turritopsis morph through multiple stages during their life cycle.But unlike butterflies,if Turritopsis get wounded or if times get tough,they can morph backwards,reverting to their immature polyp form until conditions improve.
但是 裸鼹鼠即使再厉害 也只能暂停年长过程—— 灯塔水母却能“返老还童”。和蝴蝶一样 灯塔水母在生命不同阶段不断变化。与蝴蝶不同 灯塔水母受伤或条件艰苦时，会“退化”，保持在不成熟的水螅态 直到条件好转。
They're like,real life phoenixes.However if humans could somehow imitate Turritopsis' trick,it might not give us the kind of eternal youth we'd be looking for...for one thing,melting into an amorphous blob where our cells are reorganized and reprogrammed with new functions would not only be a mess;it would likely turn our brain cells into skin or muscle cells-and vice versa-erasing our memories and our sense of self.
它们就像现实版的凤凰。但是 如果人类也能模仿灯塔水母的技能，结果可不是我们理想的“永葆青春”...一方面 人类返老还童时 细胞重组 重新改造出新功能不仅会导致一团糟;还会使脑细胞变为皮肤或肌肉细胞 反之亦然--让我们失去记忆 忘记自我。
And no matter what,eternal youth wouldn't make us invincible-in fact,the longer a creature lives,the more time it has to get chomped,starved,or smooshed.So eventually,every naked mole rat,pine tree,and jellyfish will ultimately meet its end-because it's possible to be immune to aging,but not to death.
无论如何 永葆年轻不能让我们永远无敌--其实 生物存活得越久，被咬死 饿死 砸死的机会越多。最终 每只裸鼹鼠 松树和水母 都会死 毕竟 老不死的不都是老死的。