Why do our bodies age? - Monica Menesini

翻译人员: YU WANG 校对人员: Chen Zou

In 1997, a French woman named Jeanne Calment

1997年， 一位叫珍妮·卡尔芒的法国女士

passed away after 122 years and 164 days on this Earth,

在活了122年164天后于世长辞

making her the oldest known person in history.

这使她成为历史记载 上最长寿的人

Her age was so astounding

由于她的年龄如此令人震惊

that a millionaire pledged $1 million to anyone who could break her record.

甚至有一位百万富翁愿意付出一百万美元 给任何可以打破她长寿记录的人

But in reality, living to this age or beyond

但事实上 能活到这个年纪或以上

is a feat that very few, maybe even no humans,

是个十分罕见的盛宴 非常少，甚至没人

are likely to accomplish.

可以完成这个目标

Human bodies just aren't built for extreme aging.

人类的身体不是为 极端的年龄而建造的

Our capacity is set at about 90 years.

我们的年龄范围大概是90年

But what does aging really mean

但是年老真正意味着什么?

and how does it counteract the body's efforts to stay alive?

它又是怎样对抗我们 身体存活所付出努力的呢?

We know intuitively what it means to age.

我们直觉上知道年龄意味着什么

For some, it means growing up,

对于某些人来说 年老是成长

while for others, it's growing old.

对于另一些人来说 意味着变老

Yet finding a strict scientific definition of aging is a challenge.

然而 寻找严格科学意义上的 年老的定义是一个挑战

What we can say is that aging occurs when intrinsic processes

我们可以说的是 年老发生在一个内在性的过程

and interactions with the environment, like sunlight,

以及我们与环境的接触 比如说阳光

and toxins in the air, water, and our diets,

和在空气 ，水和 我们食物里的毒素

cause changes in the structure

引起结构上的变化

and function of the body's molecules and cells.

以及人体的分子和细胞功能的变化

Those changes in turn drive their decline,

这些变化造成它们数量的减少

and subsequently, the failure of the whole organism.

最终导致 整个有机体的凋零

The exact mechanisms of aging are poorly understood.

人们对人体老化的确切机理 知之甚少

But recently, scientists have identified nine physiological traits,

但是在近年，科学家鉴定出 九个生理学的特征

ranging from genetic changes

从基因的变化

to alterations in a cell's regenerative ability

到一个细胞再生能力的变更

that play a central role.

这个能力起着一个核心的角色

Firstly, as the years pass, our bodies accumulate genetic damage

首先，随着时间的流失 我们的身体体累计了很多基因的伤害

in the form of DNA lesions.

以DNA损伤的形式表现出来

These occur naturally when the body's DNA replicates,

当身体的DNA复制时 这些就自然发生了

but also in non-dividing cells.

但这些也在非分裂的细胞里发生

Organelles called mitochondria are especially prone to this damage.

这个被称为线粒体的细胞器 特别容易出现这种损伤

Mitochondria produce adenosine triphosphate,

线粒体产生三磷酸腺苷

or ATP,

或者ATP

the main energy source for all cellular processes,

是所有的细胞过程的主要能量来源

plus mitochondria regulate many different cell activities

加上线粒体会调节 许多不同的细胞活动

and play an important role in programmed cell death.

并在程序性细胞死亡中 起到重要作用

If mitochondrial function declines,

如果线粒体功能减弱

then cells and, later on, whole organs, deteriorate, too.

细胞， 以及再后来的 整个器官也会衰亡

Other changes are known to occur in the expression patterns of genes,

其它已知变化以 基因模式的表达发生

also known as epigenetic alterations,

这也被称为表观遗传的改变

that affect the body's tissues and cells.

这个改变会影响机体的组织和细胞

Genes silenced or expressed only at low levels in newborns

一般不表达 或仅在新生儿中部分表达的基因

become prominent in older people,

在老年人中变得常见

leading to the development of degenerative diseases,

这会导致退化性疾病

like Alzheimer's, which accelerate aging.

比如会加速衰老的阿茨海默症

Even if we could avoid all these harmful genetic alterations,

即使我们能够避免所有这些 有害的基因变异

not even our own cells could save us.

甚至我们自己的细胞都不能拯救我们

The fact remains that cellular regeneration,

事实是 细胞再生功能

the very stuff of life,

生命重要的东西

declines as we age.

随着我们年龄的增长而减弱

The DNA in our cells is packaged within chromosomes,

在我们细胞中的DNA 被包含在染色体内

each of which has two protective regions at the extremities called telomeres.

每个染色体都具有在末端的两个保护区域 叫做端粒

Those shorten every time cells replicate.

每次细胞复制时 端粒会缩短

When telomeres become too short,

当端粒变得太短时

cells stop replicating and die,

细胞会停止复制并且凋亡

slowing the body's ability to renew itself.

减缓机体的自我更新能力

With age, cells increasingly grow senescent, too,

随着年龄的增长 细胞也会日益衰老

a process that halts the cell cycle in times of risk,

这个过程终止在 危机的时候细胞的循环

like when cancer cells are proliferating.

就像当癌细胞增殖

But the response also kicks in more as we age,

但这个反应也因为 我们的年龄而减弱

halting cell growth and cutting short their ability to replicate.

阻止细胞的生长和 减弱它们的繁殖能力

Aging also involves stem cells that reside in many tissues

衰老还涉及了驻留在 许多组织中的干细胞

and have the property of dividing without limits to replenish other cells.

那些具有无限分裂 以补充其他细胞的细胞

As we get older, stem cells decrease in number

当我们变老的时候 干细胞的数量会减少

and tend to lose their regenerative potential,

并且往往会失去 其再生的潜能

affecting tissue renewal and maintenance of our organs original functions.

影响组织更新和维修 我们的器官原有的功能

Other changes revolve around cells' ability to function properly.

其它的变化包含了 细胞正常工作的能力

As they age, they stop being able to do quality control on proteins,

随着它们年龄的增长 它们停止了对蛋白质的质量控制

causing the accumulation of damaged and potentially toxic nutrients,

这会造成损伤的和 具有潜在毒性的营养物质的积累

leading to excessive metabolic activity that could be fatal for them.

并且导致过多的代谢活性 它们可能是致命的

Intercellular communication also slows,

细胞间的信息通讯也缓慢下来

ultimately undermining the body's functional ability.

最终破坏了 人体机能的作用

There's a lot we don't yet understand about aging.

关于老化 还有很多我们不知道的

Ultimately, does longer life as we know it come down to diet,

最终，更长的寿命 是不是像我们知道的归因于饮食

exercise,

运动

medicine,

医疗条件

or something else?

或许还有其它的元素？

Will future technologies, like cell-repairing nanobots,

未来的科技的发展， 会像进行细胞修复的纳米机器人

or gene therapy,

或者基因疗法

artificially extend our years?

人为地延长我们的寿命？

And do we want to live longer than we already do?

而且我们真的想 比我们现在活得长久？

Starting with 122 years as inspiration,

以122年为激励的起点

there's no telling where our curiosity might take us.

我们不知道我们的好奇心会带着我们去向何处