（原文来自科学松鼠会，转载请注明。）

Exercise confers huge health benefits, so why does it often feel like such a chore? Evolutionary biologist Daniel Lieberman explains the paradox

运动对健康有莫大好处，但为何总让我们觉得运动是件麻烦事。进化生物学家丹尼尔李伯曼为我们解释了这一矛盾。

Why did you start to study the evolution of running and exercise?
是什么使您开始研究跑步与运动方面的进化的？

I got interested in how we hold our heads still when we run. It began when my colleagues and I were doing some experiments with pigs as models. It is very uncomfortable to watch a pig run: its head bobs all over the place. But animals that are good at running, like us, are extremely good at keeping the head still, because it is important for gaze stabilisation. We started thinking about humans and chimps, and came up with hypotheses about how we evolved head stabilisation to run.

我对奔跑时人们头部相对静止这一现象很感兴趣。我的研究始于我与我的同事对猪的实验。观察猪的奔跑听不舒服的：猪跑的时候摇头晃脑。但那些善于奔跑的动物，例如人类，却可以非常好的控制我们的头部，因为这对视线稳定非常重要。我们研究人类和猩猩后，得出了一个假设，即人类如何进化出在奔跑时保持头部稳定这一能力。

Why do you think head stabilisation evolved for running, and not another form of movement?
为什么您会认为头部稳定这一能力是从奔跑中、而不是从其他的运动形式中进化而来呢？

If you watch someone with a ponytail running, the ponytail bobs up and down. That's because of the pitching forces acting on the head. The head itself stays very stable. There are special mechanisms – the semicircular canals in human heads are greatly enlarged relative to apes, for instance – that give us a much greater ability to perceive and react to rapid accelerations of the head.

Walking does not create such accelerations. And I don't think our ancestors were jumping on trampolines or hitting each other on the head so much. The only explanation we can come up with is running.

如果你观察一个扎马尾辫的人跑步，马尾辫会上下跳动，这是因为振动力作用于头部的关系。但头部本身却保持的很稳定。这里有一个特殊的机制--与猿相比，人类头部的半规管大大扩大，这就让人类对头部较大加速度的接受与反应能力大大加强。而且我觉得人类的祖先也不太可能经常跳蹦床或者互相碰撞自己的头部（-_-|||）。所以我们能得出的唯一的解释就是奔跑。

Being able to run is one thing – how did we then go on to become endurance athletes?
有能力奔跑是一个方面--人类如何继续进化成具有耐力的运动员？

We evolved from very non-active creatures. A typical chimp will walk 2 to 3 kilometres a day, run about 100 metres and climb a tree or two. Your average hunter-gatherer walks or runs 9 to 15 kilometres per day, and we have all these features in our bodies, literally from our heads down to our toes, that make us really good at long-distance walking and running.

目前的人类是从一种不太活跃的生物进化而来。黑猩猩一般可以行走2-3公里，可以跑100米并爬爬树什么的。采集狩猎者则进行9-15公里的行走或奔跑，而咱们具有上述两者的这些特征，从头到脚都具备，这就使得人类很善于进行长距离的行走或奔跑。

I and my colleagues at the University of Utah, Dennis Bramble and David Carrier, think the key advantage for humans was persistence hunting, whereby you run very long distances to chase animals in the heat and run them into heat stroke. We can run for very long distances, marathons in fact, at speeds at which other animals have to gallop. That's not an endurance gait for quadrupeds, because they cool by panting – short shallow breaths. You can't pant and gallop at the same time. If you make an animal gallop in the heat for 15 minutes or so, on a hot day, you'll kill it.

我和犹他大学的同事丹尼斯和大卫认为人类的关键优势在于狩猎的持久性，人类可以头顶烈日长距离的追逐猎物，并把猎物追至中暑。人类可以以很快的速度跑非常长的距离，像马拉松这种，而对于其他动物来说，它们则必须飞驰才行。对于四足动物来说飞驰并不是一个具有持久性的步法，因为它们需要利用喘息（即短促的呼吸）来降低体温。边喘息边飞奔是不可能完成的任务。如果你让一个动物大热天在烈日下飞奔15分钟之类的，根本就等于杀了它。

But we have adaptations for this kind of endurance running?
那我们人类适应了这种耐久力的奔跑么？

Yes. Our bodies are loaded with all kinds of features: short toes that require less energy to stabilise and generate less shock when running; the Achilles tendon that stores and releases energy appropriately as we run; the large gluteus maximus muscles that steady the trunk; and stabilisation of the head. I'm a middle-aged professor, I'm not a great specimen of an athlete, but I can easily run a marathon at a speed that would cause a dog my size to gallop.

对。人类的身体有非常多的特征：不需要太多能量就可以保持稳定的短脚趾，在奔跑时不会产生太大的冲击。跟腱则存储能量并在奔跑时释放能量。臀大肌保持躯干的稳定，还有就是头部的稳定。对我来说我是个中年教授，我不是一个运动员的样本，但我可以很轻松的跑马拉松，要是像我这么大体积的狗以我的速度奔跑的话，它得飞奔才行。

What's your best marathon time?
您最好的马拉松成绩是多少呢？

[Laughs] 3 hours and 34 minutes. There are guys who can run almost twice as fast as me.

【笑】3小时34分钟。有好多人的速度可以比我快两倍呢。

Still, if you made an animal run that far at your speed, you would...
如果您让某个动物以这种速度跑的话，您会。。。

I'd have dinner.

我就能吃上一顿大餐了（跑死了）。

Why, in spite of our adaptations, have we gone from endurance athletes to couch potatoes?
除了人类的适应性之外，为啥人类从耐久力强的运动选手变成又肥又懒的沙发土豆了呢？

It was incredibly recently in history that a large number of humans have been freed from having to do physical activity. My argument, from an evolutionary perspective, would be that not having regular physical activity every day is pathological and abnormal. In a lot of medical studies, we compare people who are sick with controls. But who are those controls? They are relatively sedentary Westerners. I'd argue that we are comparing people who are sick to people who are abnormal and semi-pathological.

人类是从很近期才开始不需要做体力活动的。从进化论的角度来说，我的观点是，每日缺乏规律的体力活动是病态且反常的。我们在很多医学研究中比较了病人与对照组。这些对照组是啥呢？就是很少运动的西方人。我想说的是我们是拿病人与反常的、半病态的人进行比较。

If being inactive is pathological and abnormal, then how come we hate exercise so much?
如果说不活动是病态且反常的，那为什么我们如此痛恨运动呢？

There was never any evolutionary selection pressure to make us like exercise. If you are a Neanderthal or Homo erectus or an early modern human, you didn't think, "Gee, I'm going to go for a run so that I'm not going to get depressed". They had to go long distances every day in order to survive. Not exercising was never an option, so there was never any selection pressure to make people like exercise. On the contrary, there was probably selection to help people avoid needless exercise when they could. Some hunter-gatherers had diets of about 2200 calories a day. When your energy intake is that low, you can't afford to go for a jog just for fun.

从没有什么进化选择压力让人类喜欢运动。如果你是尼安德特人或者直立人或是早期现代人，你不会想：“天，我得跑一跑才不会郁闷”。他们每天要走或跑那么长距离是为了要生存。没有办法不进行锻炼（原句直译太怪），所以在是否喜欢运动这件事上并没有进化选择压力。另一方面，或许存在某种进化选择，让人避免不需要的运动。一些狩猎采集者每日从饮食中获取2200大卡的热量，这么低的能量摄入，让他们没办法把慢跑当做娱乐。

So evolution selected for traits that made us relax or be lazy?
所以说进化选择某些特性让人类更放松或更懒惰？

Of course. Just like any time you crave sugary, fatty foods – that would have been advantageous for early humans. It's only now that they have become maladaptive.

当然啦。就像你时时刻刻想吃甜食、油腻的食物--这是对早期人类来说有优势的（进化特制）。只是在目前来看这种特质是不利于适应的。

When you walk into a train station and there is a staircase and an escalator, your brain always tells you to take the escalator. Given a choice between a piece of cake and a carrot, we always go for the cake. It's not in your best interest, but it's probably a very deeply rooted evolutionary instinct.

你走进火车站的时候，眼前有楼梯和电梯，你的大脑总是告诉你让你去乘电梯。从蛋糕和胡萝卜之间，咱们总是选择蛋糕。这种选择并非最佳的，但它或许是深深的根植于进化的本能当中。

What are the consequences of the modern sedentary lifestyle?
当代的这种久坐式生活方式会产生何种后果？

It's hard to think of one disease that is not affected by physical activity. Take the two major killers: heart disease and cancer. The heart requires exercise to grow properly. Exercise increases the peripheral arteries and decreases your cholesterol levels, it decreases your risk of heart disease by at least half.

Breast cancers and many other reproductive tissue cancers also respond strongly to exercise. Other factors being constant, women who have engaged in regular vigorous exercise have significantly lower cancer rates than women who have not. Colon cancer has been shown to be reduced by up to 30 per cent by exercise. There are also benefits for mental health – depression, anxiety, the list is incredibly long.

很难想象一种疾病不受体力活动的影响。以人类健康的两个主要杀手：心脏病和癌症来说，心脏需要运动来进行良好生长。运动提高周边动脉并降低胆固醇水平，这可以降低至少50%的心脏病风险。乳腺癌和很多其他生殖系统癌症受运动的影响也颇大。假定其他条件不变，经常进行活力运动的女性得癌症的几率比不活动的女性显著低很多。运动可以使得直肠癌的几率降低高达30%。运动对精神健康也大有裨益，可以改善抑郁、焦虑。总之运动的好处非常多。

What can we do about our maladaptive traits?
对于人类的适应不良的特性，我们又能做些什么呢？

If we want to practice preventive medicine, that means we have to eat foods that we might not prefer, and exercise when we don't want to. The only way to do that is through some form of socially acceptable coercion. There is a reason why we require good food and exercise in school – otherwise the kids won't get enough of it. Right now we are dropping those requirements around the world.

If we are going to solve these health problems, we have to push ourselves to act in our own self-interest. As a society, as a culture, we have to somehow agree that it's necessary or face the consequence – which is billions of unfit, overweight people.

如果我们要进行预防医学的干预，就意味着我们得吃些我们不想吃的东西、做我们不想做的运动。唯一的做法是通过某种形式的社会性可接受的强制。这就是为什么我们需要学校提供良好的膳食和运动--否则孩子们没有办法获取足够的健康饮食和运动。现在我们将此种要求置于全世界范围内。如果我们要解决健康问题，我们必须逼迫自己做出自利性行为。而对社会、文化而言，在某种程度上我们得面数以亿计不健康、超重的人这种结局。

Has evolution given us any instincts that promote exercise?
进化是否给予人类促进运动的本能？

Yes. It's important to recognise that the body isn't adapted only in one way or another. There are multiple competing adaptations. While it's true that many of our instincts are to not like exercise, we also have other adaptations that make us enjoy exercise. The most obvious example is the runner's high.

是的。我们要认识到身体并非只有几种适应性的选择。有多种相互竞争的适应。虽然人类很多的本能让我们不喜欢运动，但人类还有其他的适应性让我们喜欢运动。最明显的例子就是跑步者的愉悦感。

What's the evolutionary advantage of the runner's high?
跑步者的愉悦感在进化上有什么优势呢？

Imagine you are chasing an animal, and you have to keep going. When you are chasing, you are usually also tracking, which is all about observation. You are looking for clues in the environment. What does a runner's high do? It makes everything more intense. It stimulates your perception and your sensory awareness.

想象一下你正在追逐一只野兽，你必须不断奔跑。而你追逐的时候，同时也进行追踪，而追踪就是观察。你从环境中找寻线索。而跑步者的愉悦感起到什么作用呢？它让一切都变得非常清晰。它刺激了你的感官和感觉器官的意识。

I can give you an example: I ran the London marathon a few years ago, and as I was nearing the finish I remember running by Big Ben and thinking, "Wow, Big Ben is really big." And then I remember thinking to myself, "Oh, I must be high."

举个例子吧。我几年前在伦敦跑马拉松，当我快接近终点的时候我记得我跑过大本钟，然后我就想“哇，大本钟真的很大呀。”之后我就想到我自己“嗯，我得兴奋起来。”

（原文来自科学松鼠会，转载请注明）