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为什么我们无法永生?

Why Don’t Humans Live for More than 100 Years? | Physicist Geoffrey West

大家都知道 我们赖以为生的
Since metabolism underlies you know pretty much the way we live,
一切有机体赖以为生的 都是代谢
any organism lives, because it is the way energy and resources
因为这是能量和资源提供给细胞的方式
are being supplied to cells and so forth.
你可以确定或者计算出许多有关生物体的信息 例如它们的生长模式
You can determine, calculate many things about organisms, about their growth patterns, how
它们生长的方式 从幼体到成熟需要的时间 尤其是那困扰我们许多人的问题
they grow, how long they take to mature—and in particular one that concerns many of us,and
我们能活多久?
that is: how long we live?
是什么决定了我们能否长寿?
What determines our longevity?
事实上 我最初开始从事这方面工作的原因是
And, in fact, that’s what got me into this work originally was I became very intrigued
当我进入五十岁时 我开始对衰老和死去的现象越来越有意识
in my fifties about the phenomenon of aging and of dying that I became more and more conscious
我开始注意我的身体和生理机能方面发生的变化
that things had been changing in my life in terms of my body and my physiology.
同时也因为 我的身边已经有朋友离去了
And that already I’d had friends die.
于是我对“长寿的原因究竟是什么?”开始感兴趣
And so I became intrigued as to “what is that?”
同时作为一个物理学家 我并不想知道衰老和永生的运行机制
And I also became intrigued very much as a physicist not asking what is the mechanism,
而是想要知道这个问题的答案:
the systematics about aging and immortality, but the very question “What determines 100
究竟是什么决定了一个人长达一百年的寿命?
years for the lifespan of a human being?
为什么是一百年 而非一千年或者一百万年?
Why is it a hundred years, not a thousand years or a million years?”
还有就是 与我们身体有着几乎相同物质构造的老鼠
And also related to that, why is it that a mouse, which is made of pretty much the same
(我是说我们和老鼠在某些大概的层面上确实极其相似)
stuff as we are (I mean we’re almost identical really in some kind of coarse grained level
为什么它们就只能存活两到三年?
looking at things), how come a mouse only lives two to three years?
所以究竟是什么决定了这一切?
So what is determining all this?
如果你通晓一种隐藏在标度律之下网络理论,这种理论表明自己为标度律
And if you have this theory of networks underlying these scaling laws, manifesting themselves
你会有疑问:“有没有一种适用于寿命的标度律?”
as scaling laws, you first ask: is there a scaling law for lifespan?
这也是一个许多人已经完成的工作 那就是将寿命视为
So this is work that had already been done by many people; was to look at lifespan as
一种尺度函数 有关特殊但仍属于一般生物的哺乳动物
a function of size, for a bunch of mammals in particular but organisms in general, just
就像我们看待这些生物的新陈代谢速率尺度一样
as we looked at how metabolic rate scales across these animals.
于是我们发现 寿命的增长遵循
And what was discovered, what had been discovered was that lifespan also increases following
四分之一功率标度律 它的增长是系统性的
these quarter power scaling laws—that it increased systematically.
顺便说一下 有一个差异 或许我一会简单说一说
The one difference by the way, and maybe I’ll say a few words about this in a moment, is
相比新陈代谢速率的数据来说 有关寿命的数据
that there’s much more scatter among the data for lifespan compared to things like
更加分散
metabolic rate.
虽然说有这样一种可预测性 比如你告诉我一种哺乳动物的体型大小
So even though there is a kind of predictability—that is, you give me the size of a mammal, I will
我告诉你这种哺乳动物平均寿命-这个数字的准确性比
tell you on the average how long that mammal will live—there’s much more variance around
你告诉我一个哺乳动物的体型大小
that number than there is for saying “you tell me the size of a mammal, I will tell
我告诉你它的新陈代谢速率和它的主动脉长度 以及它应该会有多少后代等等
you what it’s metabolic rate is and what the length of its aorta is, how many children
(这些数据相对准确)更小
it should have” and so on, where there’s much less variance.
变化十分紧密
The variance is much tighter.
寿命有更多的变化
Lifespan has much more variance.
那么数字从哪里来?
Now where does that number come from?
因此这个代谢率的标度理论并且很多其他数量
So you have this theory that the scaling of metabolic rate and these many other quantities—and
——大概有50或75个这样的可测量—
by the way there’s probably 50 or 75 such measurable quantities—these are determined
系统网络中的流动限制(例如循环系统)决定了数量
by the constraints of flows in networks such as the circulatory system.
所以 你会立即意识到的一件事是关于这些流动量
So one of the things you immediately realize about those flows is that they are what we
它们就是我们所说的“消耗物” 也就意味着它们涉及到磨损
call “dissipative,” which simply means they involve wear and tear just as, you know,
就像在建筑物旁 马路上川流不息的车流
outside in those streets outside this building there’s a lot of traffic going back and
久而久之 道路就会有损坏
forth on the roads and those roads wear out.
必须有人去修理
They have to be repaired.
道路要修理 地铁要修理
The roadways have to be repaired and the subways have to be repaired.
因此可以这样说 它们从交通运输中损耗掉了
They wear out from the traffic so to speak.
并且正是这种贯穿我们复杂的网络系统的交通运输造成了磨损
And so it is the traffic through our multiple network systems produce wear and tear.
最严重的损耗发生在最终端上 在网络系统的最终段
And the most damaging wear and tear occurs at the terminal units, the terminal points
因为在我们的毛细血管或者在我们的细胞里
of these networks because they’re the smallest tubes like in our capillaries or within our
的最小的血管 (它们推动血细胞或者其它物质) 当大分子穿过它们时
cells and pushing fluid, pushing blood corpuscles or whatever it is, big molecules through them—has
会造成许多种有害的影响
deleterious effects of various kinds.
并导致损害 并且由于你有与之相关的理论 所以损害的程度是可以计算的
That causes damage, and that damage is calculable because you have a theory.
此理论会告诉你流动率以及各种尺寸数据等等
The theory is telling you what the flow rates and so on and all the sizes are and so on.
因此这些数字都是可预测的
So these are calculable.
现在你可以预测损耗发生率 并且你也可以
Now so you can calculate the rate at which wear and tear is occurring, and you can also
测量出一些其他可能会发生的数据 那就是:当有损害发生时
calculate something else that is going on, and that is: while it’s being damaged there’s
也会出现修复
also repair going on.
我们确实有自我修复的机制
And we do repair ourselves.
但是新陈代谢也决定影响着修复
But that repair is also determined by metabolism.
因为修复所需的能量就是来自于新陈代谢
That’s where the energy comes from to do repairs.
因此你可以测定许多数据 并且你可以假定这个系统将会
So you can determine all these things and then you can postulate that the system will
逐渐崩坏 当出现指定部分无法修复的情况时 系统将无法
become nonviable, that is it can no longer be sustained when a given fraction of un-repaired
再维持下去
damages occur.
因此系统最终不能再维持并且给出一个预算的
So the system eventually just cannot be sustained and so that gives you a calculation of maximum
最大寿命
lifespan.
如果你明白系统的这些运作 并且做到最好 作为一个限定尺寸的哺乳动物
This is the, you know, if you were to do the best you possibly could this is as long as
你会活得更长久
you could possibly live for a given size of mammal.
如果你做到了这些 你就能够大概明白 人类这一百年
And if you do that you can understand where, roughly speaking, this hundred years for a
来自哪里
human being comes from.
但是更重要或者同样重要的是 你可以预测出参量的值
But more importantly or equally importantly you can determine what the parameters are,
就像你轻轻调动 就可以改变寿命的旋钮
the knobs that you could conceivably turn to change that lifespan.
举个例子 怎么做才能让寿命从一百年增加到两百年
What could you do to make that go from 100 to 200, for example?
这个过程有两种方式
And there’s two pieces of that.
一是你可以减少损耗 或者你可以增强修复
One is you can decrease, of course, the wear and tear, or you can increase the repair.
这两种显而易见的方法都是作为决定寿命的参数
Those are the two obvious things, and there are parameters that determine that.
因此如果你认为损害是来自于新陈代谢 —也就意味着
So if you think about the damage that is occurring from metabolism—so that means okay, one
可以通过减少我们获取食物的数量从而降低损耗
way we could decrease damage is decrease the amount of food we take in.
这也是一种方法
That would be one way.
的确通过这种方法 大体积的动物比小体积比小体积的动物活的更长久的原因是
And indeed by the way, the reason a large animal lives longer than a small one is because
大体积的动物的每单位质量或者每个细胞的新陈代谢的速率都比小体积的动物更慢
the metabolic rate per unit mass or per cell gets systematically smaller the bigger the
等同于四分之一功率标度尺
animal, corresponding to these quarter power scaling laws.
因此按照系统性的方式下 体积越大的动物 在其细胞水平上所受到的损害越小
So less damage is done at the cellular level the bigger the animal—in a systematic way.
那么问题是: 如何进一步降低其损害?
So the question is: how do you decrease that even further?
一种是你减少进食量 称为热限制
One is you can eat less, and that’s called caloric restriction.
如果你打算节食 可能会扰乱你的生活习惯
So if you put yourself on a starvation diet it may not be so pleasant in terms of your
但是这会使你活得更长久
lifestyle, but this would predict that you live longer.
在很多以猴子和老鼠为研究对象上的已完成的实验里 大多数
And there have been experiments done, on mice in particular and some on monkeys, most of
都表明在这种理论下 产生的效果是可以预测的
which show an effect, and the effect is calculable in this theory.
并且其中的大多数实验的结果都符合以老鼠为对象测得的数据标准
And many of the experiments done on that agree with the data that’s been taken—on mice.
(但)也有些以猴子为对象的实验得出有争议的结果–并没有出现大体积的动物
There have been some controversial experiments on monkeys which have not shown as big an
寿命越长的现象
effect.
所以仍然需要进行大量的实验工作 但是还有另一种可以降低
So this is still very much a work in progress, but there’s another way you could also decrease
你的新陈代谢的方法 对于我们来说这种方法十分困难但有趣的是
your metabolism, and that’s a way that is very difficult for us but interestingly is
对地球上几乎所有的其他的生物有机体来说 却很简单
very easy for almost all other organisms on the planet.
而造成这种现象的原因是 我们人类是独特的 是所谓的“恒温动物”
And that’s to do with the fact that we are unique in that we are what’s called “homeotherms”.
即我们的体温保持恒定
Namely we keep the same temperature.
我们发现了可以保持体温恒定卓越的机制
We discovered this extraordinary mechanism of keeping our body temperatures constant.
这种机制十分有趣 因为它将我们从外界环境的
That is fantastic because it dissociates us from the external temperature, the environmental
温度隔离开来
temperature.
周围环境温度影响着我们的所有(身体机能)
Everything else is subject to the ambient temperature in their environment.
并且它如此重要的原因是:化学反应影响着新陈代谢速率
And here’s why it matters: It’s because metabolic rate is derived from chemical reactions,
化学反应与外界温度呈指数关系增长
and chemical reactions depend exponentially on external temperature, on the temperature
而且外界温度是人为设定好的
which they’re operating.
这也就意味着 温度的些许变化都会产生巨大的影响
That means a small change in temperature can have a huge effect.
因此温度上微小的增长 就会造成你的新陈代谢速率
So a small change in temperature, a small increase in temperature increases your metabolic
以指数方式快速增长
rate exponentially.
因此这就是当你在寒冷的清晨看到昆虫
So that’s why if you look at insects in the cold—when they’re cold in the morning
几乎不动的原因
they can barely move.
他们必须等到阳光能够到照射它们直到身体变暖以后 才能展翅高飞
They have to wait until the sun comes up to warm themselves and then they can start flying
或自由移动等等
around and moving around and so on.
蜥蜴以及其他(冷血动物)就是这样生存的 并且几乎我们周围所有动物也是这样的
That’s true of lizards and so on, essentially everything that’s around us.
但我们人类却不受温度的影响 因此这种特性使得我们人类十分强大并且
We are immune from that and that’s been extraordinarily powerful for us and a tremendous
非常有利
advantage.
至于对寿命的影响 如果你能够降低你的体温
Going back to lifespan, that means that if you could lower your body temperature you
你就可以降低你的新陈代谢速率 因此就减少了损害 那你就
would decrease your metabolic rate and you would decrease therefore the damage, and you
能够活的更长久
can live longer.
对于其他所有生物 这种方法的确适用
And that is indeed true of organisms, all other organisms.
如果你将它们体温保持在低温的水平 它们会活得更加长久
If you keep them at low temperatures they live exponentially longer.
它们的寿命会十分长久 因此这种方法效果很神奇
They live much longer so it’s a fantastic effect.
非常巨大的影响
It’s a huge effect.
有一个次要评论要顺便一提–这种方式对于我们这个时代来说十分关键–并且
And by the way one tangential remark for that—and that is a critical one in our times—and
可以用来处理全球变暖问题
that is to do with global warming.
我认为其中一件事对大多数人来说有点难以理解
One of the things that I think is a bit mysterious to many people, in the kind of intelligent
那就是: 周围环境一两度的温度变化为什么会
layperson, is that: why should one or two degrees change in the ambient temperature
对身体产生如此剧烈的影响
around us make any bloody difference to anything?
毕竟每天我生活的环境从晚到早经常有四十度的温差
After all where I live the temperature often changes by 40 degrees from night to day.
因此周围巨大的温度改变影响着我们 周围环境温度仅上升一点
So we have these huge changes, yet the ambient, you know, just this little increase in the
平均每度都有着巨大的影响
ambient, in the average temperature have such a big effect.
原因是像生长率和死亡率以及诸如此类的因素都与生长有关
The reason is that things like growth rates and death rates and everything to do with
因此 农业生态系统 甚至整个生物系统和生物圈
growing and therefore agriculture, but the whole ecosystem, the whole biosphere is exponentially
都极易受温度的影响
sensitive to a change in temperature.
因此一两度的改变也会造成指数级的变化 而且从我们的观点来看 其中的一些变化
So one to two degree change has an exponential effect, and some of that is, from our viewpoint,
有些极具破坏性 有些却十分有益
highly deleterious and some may actually be advantageous.
但是我认为存在一个十分重要的问题–这里恐怕
But I think this is an incredibly important point that—I’m afraid I’m a little bit
要稍稍批评研究全球变暖的同事–他们并不擅长
critical here of my colleagues who work in global warming—they have not been very good
将这些理论向政客 尤其是美国的政客
at getting this across, especially obviously to politicians and especially, of course,
表达清楚
the politicians in the United States.
但是回到关于寿命更具体的问题上来 如果我们可以服用些药物
But going back to the more parochial issue of lifespan, if we were to take drugs that
这些药物可以降低我们的体温(已经在老鼠上成功实验)
could lower our body temperature (and this has actually been done for mice again) it
它可以相应地增加它们的寿命
increases concomitantly their lifespan.
降低它们的新陈代谢速率并提高它们的寿命
Decreasing their metabolic rate increases their lifespan.
并且在可预见的未来里 大众会接受这种延长寿命的治疗方法
And that’s been seen and it is in agreement with the theoretical predictions.

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视频概述

生命的大多数能量来源于新陈代谢,新陈代谢则极易受温度的影响

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收集自网络

翻译译者

海底风

审核员

瞌睡虫儿

视频来源

https://www.youtube.com/watch?v=TYVNZrxCoXU

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