未登录,请登录后再发表信息
最新评论 (0)
播放视频

有“自私基因”这回事吗?

Why are genes selfish?

自私基因这一说法
The term theselfish gene has seen
一直饱受争议
its share of confusion and controversy.
表面上看来 它似乎是说
On its face, it seemslike it might be saying
生物学注定了我们会变得自私
that biology destines us to be selfish.
并且 向外普及此概念的作者
And also, the author ofthe book popularizing it,
用他自己的话说 也并不是很擅长交际
well,to use his own words, he’s not much of a diplomat.
为了战胜这些偏见
To try to overcome some of that baggage,
我们将从三个方面去慢慢分析自私基因
we’re gonna take it slow and analyze this term,selfish gene, in three parts.
第一个方面
In the first part,
我们将明确基因这一词的定义
we’ll work up a definition of the word gene
从而让我们在“什么是自私”上达成一致
so we can agree on exactly what it is we’re calling selfish.
第二方面
In the second part,
我们来看看一个成功的基因到底有哪些具体的策略体现
we’ll look at what kinds of strategies a successful gene might have.
剧透一下 并非所有的策略都最终产生了自私的生物
Spoiler alert, not all the strategies end up producing creatures that are selfish.
本部分就先说到这
And that’s actually wherethis video will end.
第三方面由之后的视频组成 深入讲解每一种策略
the third part will consist of following videos that they are deeply into each kind of strategy,
并且通过模拟 来帮助理解 什么时候以及为什么策略会起作用
using simulations to understand when and why that strategy can work.
在先前的视频中 我们已经论述了 那些准确自我复制的生物
In previous videos, we’re been dealing with creatures that replicate and make exact copies of themselves,
除非遇到偶然的复制错误 我们称之为突变
except for the occasional copying mistake, we call it a mutation.
但是 大多数生物是不会发生突变的
most real creatures don’t actually work this way, though.
在生物学的工作方式下
The way biology happens to work,
生物通过复杂的化学过程得以诞生和维持
creatures are built and maintained through complex chemical processes
这些过程都遵循一种分子形式的遗传信息的编码
which all follow the information encoded in a kind of molecule
我们称之为脱氧核糖核酸
called deoxyribonucleic acid,
简称DNA
or DNA for short.
当大多数动物及其他生物 进行有性生殖时
When creatures reproduce sexually, which most animals and many other organisms do,
它们混合来自父母亲的DNA产生子孙后代
they produce offspring with a mixture of DNA from their parents.
甚至 在单细胞生物进行无性繁殖时
And, even single-celled organisms that do reproduce with only one parent
也常常通过某些方式与别的个体相互交换DNA
often have some way of swapping DNA with each other.
因此生物繁衍并不靠完全地复制
So creatures don’t truly replicate
因为他们的先辈不是完全一致的复制品
because their descendantsaren’t identical copies.
它们有不同的DNA
They have different DNA.
实际上只有部分DNA片段是复制的
The sections of DNA arewhat actually replicate.
现在我们已经知道了什么是DNA 但是什么是基因呢?
So that’s DNA, but what is a gene?
我们来简单的定义一下
We’re gonna use the simple definition
一个基因就是一段DNA分子
that a gene is a section of DNA
存在于生物体内 并且决定了生物的一个特征
that lives inside a creature anddetermines one trait.
任何生物都有很多基因
And any creature has many genes,
这些基因一起决定了生物的所有性状
which, together, determine all of its traits.
这个解释非常接近孟德尔对基因的定义
This is close to the definition of a gene we got from Gregor Mendel
他被誉为现代遗传学之父
who’s often called the father of modern genestics
有了这个定义 在进一步了解之前
Before moving ahead with this definition,
不得不承认 我们当前对于DNA是怎样影响性状的理解
we should admit that our current understanding of how DNA affects traits
远比这个简单定义要复杂
is massively more complicated than this.
许多生物实际上有一对等位基因 这个孟德尔研究过
Many creatures actually have two versions of each gene, which Mendel did know.
同样 一个基因可以影响多个性状
Also, one gene can affect several traits.
并且 大多数的性状是被多个基因影响的
And, most traits areaffected by several genes.
不同的基因能够影响其它基因的功能
And different genes canaffect how others work.
而且 一段DNA可以有多种读取方式
And, one section of DNA can be read in multiple ways.
并且 它所发挥的作用需要通过多步化学作用
And, it’s all mediated bymulti-step chemical processes.
并且依赖体内环境
And it also depends onthe environment inside
和外部环境 也受时间影响
and outside the body, and on timing.
因此 这是一个庞大的概念
So, yeah, it’s a big mess.
所以 如果你发现你自己用简单的
So if you find yourself making a simple
因果关系来讨论
cause and affect argument about
任何特定的性状的遗传学理论 尤其在人类身上
the genestics of any particular trait, especially in humans,
你应该更加要仔细了 因为这可能比你所认知的要更加复杂
you should be careful, because it’s probably more complicated than you realize.
但是 话虽如此 简单的定义
But with all that said,our simple definition
将会使一些基本法则更易于理解
will make it easier to think about some basic principles,
这些法则在更加复杂的现实中依然适用
which still apply in the more complicated reality.
我们的定义需要最后的调整
And our definition needs one final tweak.
一个基因并不是真正的一段DNA物质
A gene isn’t really aphysical chunk of DNA.
基因实际上是DNA的一种形式
It’s actually a patternof DNA
可以存在很多份 并且在某些生物内
that can exist in many copies, which might be in several
这些拷贝可以同时存在或随时间推移而存在
bodies at once or over time.
因此 尽管生物只能有一次生命
So, while the creature only lives once,
基因却具有潜在地永久性
a gene is potentially immortal.
从长远来看 竞争只发生在基因之间
In the long term, competitionis only between genes.
所以 基因是生物界自然选择的单元
So genes are the units ofbiological natural selection.
这是这个视频的重要观点
This really is the key idea in this video.
基因是自然选择的单元
Genes are the units of natural selection.
因此 如果你把自己当做一个基因
So, if you imagine yourself
一个有自己的感觉 能够制定计划的基因
as a gene who somehow has feelings and makes plans,
你会用什么策略来胜过其他的基因?
what kinds of strategies could make you successful in this competition between genes?
最明显的策略是
Well, the most obvious strategy is to
使得你的生物很适合生存和繁殖
make your creatures really good at surviving and reproducing,
即使是以牺牲其他携带竞争性基因的生物为代价
even at the expense of other creatures who might carry competing genes.
这样可能意味着你的生物非常自私 比如说
This could mean your creaturesare actively selfish, say,
通过从别人那里窃取
by stealing from others, or they
或者尽自己所能做到最好
might just be doing the best they can,
如此 恰巧将其他的生物排挤出去
happening to squeeze out other creatures.
我们在自然选择的视频中看到了一个这样的例子
We saw an example of this inthe natural selection video.
当生长快速 消耗低少的生物出现时
When faster, less efficient creatures were allowed to appear
他们将接管整个群体
they took over the population,
即使生物总数因此减少
even though the total number of creatures suffered for it.
不过 事情没有那么糟糕
Things don’t have to be so grim, though.
基因同样能够成功编码 对基因的携带者和其他生物表现出好的一面
Genes can also be successful by coding for behaviors that are good for the carriers and also for other creatures
这个内容范畴包括一些简单的策略 如消极主义
This category includes simple strategies like passivism,
这时生物会趋向于放弃某些资源 避免争斗付出代价
where creatures can tend to give up some resource to avoid a costly fight
从而免于受到伤害或者自己死亡
that might injure or even kill them.
而且这个包含一种更加复杂的表现
And it includes a morecomplex kind of behavior
我们称为互惠互利 此时生物会帮助彼此
called reciprocal altruism, where creatures help each other
期待得到对方的帮助作为回报
with the expectation of getting help in return.
神奇的是 这种策略并没有被欺骗性策略打败
The mystery here is why these strategies aren’t just beaten by cheating strategies
明明欺骗性策略利用了他人的善良之心而自己却没有善良可言
who just take advantage of the kindness without being kind themselves.
最后一个类别也是一开始最反直觉的 或者至少对我而言是这样的
The last category is also the most counter-intuitive at first, or at least it was for me.
一个基因有可能 有一个成功的策略
It’s possible for a gene to have a successful strategy
它的携带者通过减少他们自己的利益来帮助其他生物
where its carriers help others by acting against their own self-interest.
和互惠互利关系不同 这些生物牺牲他们自己的繁殖机会
Unlike in reciprocal altruism, these creatures hurt theirown reproductive chances
却不希望得到任何的回报
without needing to get anything in return.
它们是纯粹的利他主义者
They’re just plain altruistic.
这可以称为一个好的策略
This can be a good strategy,
因为基因的拷贝可以同时存在于不止一个个体中
because copies of the gene can exist in more than one individual at a time
从基因的角度来说 哪一个基因拷贝繁殖下去影响都不大
From the gene’s perspective,it doesn’t matter which copies reproduce.
因此 牺牲一个基因拷贝
So sacrificing one copy
是为了使整个群体能够生存舒适
for the good of the group can work out just fine.
有一个描述这种现象的术语叫包容性适应
One term for this is inclusive fitness.
这儿的谜团是 如何让一个基因确保
The mystery here is howa gene can make sure
它趋向于自我拷贝
it tends to help itsown copies rather than
而不是拷贝竞争性的基因
copies of competing genes.
我们在之后的视频中深入探讨第二部分和第三部分秘密
We’ll dive into the mysteries of the second and third categories in future videos.
但是从总体上看这张图表
But looking at this chart as a whole,
我们可以知道
we can see that
一个基因可以对其携带者或整个群体有积极影响
even though a gene’s effect can be good for individual carriers or whole populations,
但任何个体对基因的成功表达来说都不是必须的
neither of those are requirements for a gene to be successful.
这是因为核心观点是
This is because of thatkey idea that
基因是自然选择的单元
genes are the units of natural selection,
不是生物 也不是群体 仅仅就是基因而已
not creatures, not populations, just the genes.
对于所有的基因来说 唯一一直都要紧的是他们的拷贝复制
The only thing that consistently matters to all genes is thattheir copies replicate.
真是混蛋 对吧?
What a bunch of dicks, right?
[轻音乐]
(light music)

发表评论

译制信息
视频概述

简要介绍了基因的概念,以生动的模拟动画来解释自私基因的由来,并对自私基因这一词给出了更深入得解释。

听录译者

收集自网络

翻译译者

LearningMore

审核员

审核员XY

视频来源

https://www.youtube.com/watch?v=2mTVtToioLg

相关推荐