Name: 怠惰の進化：なぜ人間はジムに抵抗するのか｜ダニエル・リーバーマン：インタビュー全文 (The evolution of laziness: Why humans resist the gym | Daniel Lieberman: Full Interview)
Uploaded: 2025-08-29T18:32:42.000Z
Duration: 1 h 13 min 32 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

My name is Dan Lieberman. I'm a professor of human evolutionary biology at Harvard University, and I'm the author of Exercised, Why Something We Never Evolved to Do is Healthy and Rewarding.

私の名前はダン・リーバーマン。ハーバード大学の人類進化生物学の教授であり、『Exercised, Why Something We Never Evolved to Do is Healthy and Rewarding』の著者です。

Chapter 1. How Evolution Shaped the Human Body

第1章.進化はいかにして人体を形成したか

程度の副詞

If you want to understand anything about human beings, from our behavior to our biology, right, there are sort of two ways of thinking about humans and the way we are. One is a kind of a mechanistic set of explanations, right? You know, how does my immune system work? You know, how do my muscles work? You know, how does my brain, you know, create memories and how do I speak, etc. Those are the kind of bread and butter of most aspects of biology. But our bodies weren't engineered. They're not machines. They evolved. And so if you want to understand why we do what we do, why our brains work the way they do, why our feet work the way they do, why we run, you know, why our immune systems function the way they do, the only explanation for those sets of questions is an evolutionary question, you know, because evolution explains why things are the way they are. And so, you know, good biology combines both how questions, processes, with ultimate questions, you know, why explanations, which have to be evolutionary. And on top of that, because we're humans, I think you also have to add on anthropology, because just as there's an old expression, nothing in biology makes sense except in the light of evolution, I would say that nothing about human behavior makes sense except in the light of culture and in anthropology.

人間の行動から生物学に至るまで、人間について何かを理解しようと思ったら、人間や人間のあり方について2つの考え方がある。ひとつは機械論的な説明だ。私の免疫システムはどう働いているのか？筋肉はどのように働くのか？私の脳はどうやって記憶を作り出し、どうやって話すのか、などなど。これらは、生物学のほとんどの側面で重要なことなんだ。でも、私たちの身体は人工的に作られたものではない。機械でもない。進化したのだ。なぜ私たちはそのように行動するのか、なぜ私たちの脳はそのように働くのか、なぜ私たちの足はそのように働くのか、

And we need to understand the cultural component to our behaviors as well. So a really kind of full, complete explanation of anything, including exercise, but it could also be diet, it could be language, it could be anything, we really need to integrate not just, you know, standard sort of physiology and, you know, other kind of branches of biology, but we also need to think about them from an evolutionary perspective. And it always helps to include an anthropological perspective.

そして、私たちの行動には文化的な要素も理解する必要がある。ですから、運動もそうですが、食事や言語など、あらゆることを本当に完全に説明するためには、標準的な生理学や生物学の他の分野を統合するだけでなく、進化の観点からも考える必要があるのです。また、人類学的な視点を取り入れることは常に助けになります。

I started off my career as kind of a head guy. I studied fossils, and I was interested in, you know, when humans evolved and why we had sort of the shape heads we do. We have very weird heads, by the way. And I got very interested in the topic of how we stabilize our heads when we run. So if you ever, like, watch somebody running, and you see that they have a ponytail, right? That ponytail will do like this crazy figure eight, right? And it's kind of fun to follow somebody when they're running that way. And that ponytail is like an accelerometer on the head. It's telling you the forces that are acting on the head. And yet, despite all those crazy forces, we managed to keep our heads really still. And most animals, the way they keep their head still is they have, you know, a neck that comes out the back of the head, and the neck comes out of the front of the thorax, and they can kind of flex and extend their neck and keep it still. But we can't, because we have tiny little short necks that come out of the bottom of our heads. We're like pogo sticks when we run. And so I did some experiments on how we stabilize our head when we run. And that led to the realization that we have these special adaptations that evolved around two million years ago that only function to stabilize the head when you're running. And as I said, they showed up like two million years ago in the fossil record. And all of a sudden, I had this interest in how we evolved to become really good long-distance runners. And from there, it just kind of took off. I've been working in Kenya for a long time, but I've been specifically working in the western part of Kenya around the city of Eldoret. And it's a wonderful natural experiment to study how bodies are changing as we go into sort of industrial lifestyles, urban lifestyles.

私は頭の専門家としてキャリアをスタートさせた。化石を研究し、人類がいつ進化したのか、なぜそのような頭の形になったのかに興味を持ったんだ。ところで、私たちの頭はとても奇妙だ。そして、走るときにどうやって頭を安定させるかというテーマにとても興味を持ったんだ。誰かが走っているのを見て、ポニーテールをしているのを見たことがあるだろう？そのポニーテールは、狂ったように8の字を描くでしょう？そうやって走っている人を追いかけるのは、ちょっと楽しいよ。ポニーテールは頭の加速度計のようなものなんだ。頭に作用している力を教え

So because the city of Eldoret's the fifth largest city in Kenya, it's a very big, modern sort of urban sort of African city. And then just a few miles out of the city is a very rural area where there's no roads, there's no electricity, there's no running water. People are subsistence farmers, but from the same group, the Kalenjin-speaking population. And so we have a kind of a natural experiment. We can study how people's bodies change when they go from the countryside to the city. And so one of the things we were really interested in is carrying, because people, until recently, carried things a lot. I mean, everything you wanted to have, you had to carry.

エルドレット市はケニアで5番目に大きな都市で、アフリカの都市としては非常に大きく、近代的な都市です。そして街から数マイル離れたところには、道路も電気も水道もない田舎がある。人々は自給自足の農業を営んでいるが、同じカレンジン語を話す人々である。ですから、一種の自然実験ができるのです。田舎から都会に出たときに、人々の体がどう変化するかを研究することができる。というのも、つい最近まで、人々はよく物を運んでいたからです。つまり、持ちたいものはすべて運ばなければならなかった。

You carried your babies, you carried your food, you carried your water, you carried your fuel.

赤ん坊を運び、食料を運び、水を運び、燃料を運んだ。

And people there carry a ton of water. And we wanted to do some experiments on how women, especially women, carry huge amounts of weight on their head. And they don't seem to spend that much energy. And so our idea was to use a treadmill, because it's a lot easier to measure some of these things on a treadmill. And we'd have them carry the kinds of things they normally carry. We put on a respirometry mask to measure the oxygen and do some biomechanics to study how they do their gait, et cetera. So we bought this treadmill and schlepped it all these horrible roads to the nearest place we could plug it in. And then we brought the people from the area where we're doing research to the treadmill and put people on the treadmill. And if you've never been on a treadmill your whole life and all of a sudden somebody sticks you on a treadmill and you start walking, it's kind of a weird experience. And we realized that we couldn't really do the experiment because people weren't walking normally on the treadmill. So we abandoned the treadmill. After all that money and expense, we gave the treadmill to a local school and did our experiments by having people walk on ground as they normally do. And to me, it's a perfect manifestation, it's a perfect demonstration of the fact that treadmills are really weird. They're a strange, modern piece of equipment that we buy, we spend a lot of money on, and we spend a lot of money to go to a gym that makes you work really hard to get to stay in the same place. It's the apotheosis of exercise. And that's why in the book I spend a lot of time making fun of treadmills.

そしてそこの人々は1トンの水を運ぶ。そして私たちは、特に女性がどのように大量の水を頭からかぶっているのか、実験してみたかったのです。そして、彼女たちはそれほどエネルギーを使っていないように見える。そこで私たちが考えたのは、トレッドミルを使うことだった。トレッドミルの方が測定しやすいからだ。呼吸測定用のマスクをつけて酸素を測定し、バイオメカニクスで歩行の仕方などを調べる。トレッドミルを買って、それを一番近い場所まで運んできた。そして、研究をしている地域の人たちをトレッドミルに連れてきて、トレッドミルに人を乗

And by the way, if you think treadmills are a form of torture, I think it's kind of interesting that kind of the modern treadmill's origins are in Victorian prisons where they were actually invented as a form of torture. They were invented to keep prisoners from enjoying themselves. They made them trudge for hours and hours on these early treadmills. I don't know anybody who really enjoys being on a treadmill. Most of us, if we're forced to be on a treadmill, we either listen to a podcast or some music or watch something on our iPhones or whatever to kind of make it tolerable. But they really kind of, to me, epitomize how so many modern forms of exercise are kind of like cod liver oil. They're not really pleasant, right? We do them because they're good for us, but it's not fun. And so it's like taking your medicine. I study the human body and why it is the way it is. And I'm especially interested in the evolution of physical activity. And as I've been studying walking and running and various other sort of physical activities, it's become really clear to me that a lot of people are exercised about exercise. They're anxious. They're confused. They don't understand what's the right amount of exercise to do. They have trouble getting off the couch. And they feel kind of shamed and blamed for not being as physically active as they might like to be. And so I wanted to write a book to try to debunk a lot of myths about physical activity and about exercise using the lenses of evolution and anthropology. So the word exercise comes from the Latin exercisio, and it meant to train. So we still do math exercises or soldiers do exercises to get fit. But eventually the term has changed its meaning and it's developed new meanings. So on one hand, it means to do voluntary physical activity for the sake of health and fitness. That's that kind of sort of fitness, physical activity kind of exercise. But on the other hand, it also means to be exercised. It means to be upset, to be confused, to be anxious, to be kind of worried about something. And then again, we get exercised by our math exercises. And so to me, it's part and parcel of this strange concept of exercise. It's this modern idea of doing voluntary, discretionary physical activity for the sake of health and fitness. But we don't do it often. Most people don't do it because they want to. They do it because it helps stave off death and decrepitude. And in the modern world, of course, a lot of people are confused about it because they find it hard to do. They're not quite sure how much to do. There are all kinds of myths surrounding it. So very much people are exercised about exercise today. And really, I think that by shining the light of evolution and using kind of an anthropological perspective, my goal really is to help people be less exercised about exercise.

ところで、トレッドミルが拷問の一種だと考えているのなら、現代のトレッドミルの起源がビクトリア朝の刑務所にあることは興味深い。囚人に楽しみを与えないために発明された。初期のトレッドミルで何時間も何時間も足踏みさせられた。トレッドミルを楽しんでいる人を私は知らない。私たちのほとんどは、トレッドミルに乗らざるを得ない場合、ポッドキャストや音楽を聴いたり、iPhoneで何かを見たりして、なんとか耐えられるようにしている。でもそれは、現代の多くの運動がタラ肝油のようなものであることを象徴している。あまり気持ちのいい

I would say that the definition I use of exercise is pretty much the bog standard definition that people in the fitness, exercise science world use. It's important to make a distinction between physical activity and exercise. So physical activity is just moving. When you do anything, go shop, pick up your groceries and take them to your car, that's physical activity. When you sweep the kitchen floor, that's physical activity. But exercise is discretionary, voluntary physical activity for the sake of health and fitness. So it can include everything from sports to running on a treadmill to going for a walk. I think the paradox of exercise is that everybody knows it's good for them. I don't know that really anyone who says they don't want to ever exercise. But the paradox is that most things that are good for us kind of want to do. But exercise is kind of the reverse. It's something that we all know we want to do. It's good for us.

私が使っている運動の定義は、フィットネスや運動科学の世界の人たちが使っている標準的な定義です。身体活動と運動を区別することは重要です。身体活動とは、ただ動くことです。買い物に行き、食料品を受け取り、車まで運ぶ。台所の床を掃除するのも身体活動だ。しかし、運動とは、健康やフィットネスのために任意で行う身体活動のことです。スポーツからトレッドミルでのランニング、散歩まで、あらゆるものが含まれる。運動のパラドックスは、運動が体にいいということを誰もが知っているということだと思う。絶対に運動したくないという人を私は

And yet a lot of us have a hard time doing it. The proof is in the data. According to the CDC, only about 20% of Americans get the very minimum levels of exercise that every health organization in the world thinks is the minimum for an adult, which is 150 minutes a week. So 80% of us really struggle and fail to get the very basic amounts of exercise. But almost everyone says that they want to get enough exercise. The most common reason that people don't like to do exercise when you ask them is that they don't have time. They find it stressful and they're busy. And that's a legitimate concern for a lot of people. Imagine if you have to commute a long distance, you have a job that is very sedentary, you've got to deal with your kids in the evening, or maybe you have two jobs or whatever. It's very challenging for people to exercise and to find the time in the modern world. The other reason that people often give for not exercising is they don't like to.

しかし、私たちの多くはそれを実行するのに苦労している。その証拠はデータにある。CDCによると、世界中のあらゆる健康団体が成人として最低限必要だと考えている運動量、週150分を、アメリカ人の約20％しかしていない。つまり、私たちの80％は、ごく基本的な運動量を確保するのに苦労し、失敗しているのだ。しかし、ほとんどの人は「十分な運動をしたい」と言う。運動が嫌いな人の最も多い理由は、「時間がない」というものだ。ストレスになるし、忙しい。それは多くの人にとって正当な悩みだ。長距離を通勤しなければならない人、座りっ

They find it uncomfortable. They find it unpleasant. They get hot and bothered and they don't feel like they get much reward out of it. And so there's a lot of inertia that prevents people from doing it. They have a hard time getting off the couch. And

彼らはそれを不快と感じる。不快に感じる。暑苦しくなるし、報酬も得られない。だから、惰性に流されてなかなか実行に移せないのだ。ソファからなかなか離れられないのだ。そして

I think we need to be compassionate towards both of those reasons. Because yes, people are stressed for time. And yes, it is often unpleasant and unfun. But we make them feel bad about that.

どちらの理由に対しても、私たちは思いやりを持つ必要があると思う。なぜなら、人は時間のためにストレスを感じているからだ。そして、多くの場合、それは不快で楽しくない。でも、私たちはそのことを嫌な気分にさせてしまう。

We make them feel bad for being stressed. We make them feel bad for having that inertia when actually it's completely normal. Nobody ever exercised in the Stone Age. People were physically active when they had to be. And they might dance or do other things that were for fun. But volitionally going on a five-mile run in the morning or going to the gym to lift weights whose sole purpose is to be lifted, that's a really strange, weird, modern behavior. And there are all kinds of instincts that we have not to do it. And we shouldn't make people feel bad for having those instincts.

私たちは、ストレスがあることを悪いことだと思わせている。惰性で運動していることが悪いことだと思わせている。石器時代には誰も運動をしなかった。人々は必要なときに身体を動かしていた。そして、ダンスやその他の遊びをすることもあった。しかし、自発的に朝5マイル走ったり、ジムに行って重量挙げをしたりするのは、実に奇妙で奇妙で現代的な行動だ。そして、私たちにはそれをやってはいけないという本能がある。そして、そのような本能を持つことを悪いことだと感じさせるべきではない。

Instead, we should help them figure out ways to overcome those instincts. Because we live in a world where we now, because we've mechanized everything, we no longer have to be physically active. We now, in a very strange way, have to choose to be physically active. And that's not so easy. Oh my gosh, there are so many myths about exercise. It's hard to know where to start. But

むしろ、そうした本能を克服する方法を見つける手助けをすべきだ。というのも、私たちは今、あらゆるものが機械化され、身体を動かす必要のない世界に生きているからだ。私たちは今、とても奇妙な方法で、身体を動かすことを選択しなければならない。そして、それはそれほど簡単なことではない。運動に関する神話はたくさんある。何から始めたらいいのかわからない。でも

I would say that one myth is that our ancestors were just natural, incredible athletes who just get up in the bed in the morning and run ultra-marathons at will without much stress or difficulty, that our ancestors were really incredibly strong, that there's a trade-off between speed and strength, that it's normal to be less physically active as you get older, that there's a perfect type of exercise, perfect amount of exercise, that sports equals exercise.

神話のひとつは、私たちの祖先は生まれつきのすごいアスリートで、朝ベッドに起きると、たいしたストレスも苦労もなく、気の向くままにウルトラマラソンを走っていたとか、私たちの祖先は本当に信じられないほど強かったとか、スピードと強さはトレードオフの関係にあるとか、年をとると運動量が減るのは当たり前だとか、完璧な運動の種類、完璧な運動量があるとか、スポーツ＝運動だとか。

I could go on. The topic of exercise is just laden with myths. A common view about our evolutionary origins and about the evolution of physical activity is that we evolved from these super athlete ancestors and that civilization has contaminated us. So if you wear shoes or you drink Gatorade or you have a fancy watch or something like that, somehow that deprives you of the natural talent that you have. And if only you had been born in some little village somewhere and didn't have TV and didn't have access to all these commercial goods, that you'd be a natural, incredible athlete and that you could just get out of bed and run an ultra-marathon or something like that. A lot of these myths, to be honest, stem from, I think, this idea of this Rousseauian idea of the myth of the noble savage, that humans uncontaminated by civilization are also sort of naturally good and fine. And they also come from terrible, horrible, racist stereotypes about, for example, Africans not experiencing pain as much and Asians having some kind of natural sort of proclivity to sneak around in the dark. We all know these stereotypes and they're pernicious and they're wrong, but they've been applied in various ways to hunter-gatherers and to subsistence farmers in various parts of the world to make us feel that somehow they're these kind of basically fundamental super-athletes.

まだまだ続くよ。運動の話題には神話がつきものだ。私たちの進化の起源や身体活動の進化に関する一般的な見解は、私たちはスーパーアスリートの祖先から進化し、文明が私たちを汚染したというものだ。つまり、靴を履いたり、ゲータレードを飲んだり、派手な腕時計をしたりすると、なぜか持って生まれた才能が奪われてしまうのだ。そして、もしあなたがどこかの小さな村に生まれていて、テレビもなく、こういった商業製品を手に入れることができなかったら、あなたは生まれつきの素晴らしいアスリートで、ベッドから起き上がればウルトラマラソンを走

And when you do that, I think you do harm to people all around the planet. You do harm to those populations because you kind of dehumanize them. I mean, when they run an ultra-marathon, it's just as hard as when I were to try to run an ultra-marathon. They sweat, they toil, they get nausea, they get cramps. They do it not because it's easy for them. They do it because they value it. They think it's worth doing. And you also make people in the West feel terrible, like somehow there's something wrong with them, right? And they should throw away their shoes and eat a paleo diet or something like that. And all of a sudden, ta-da, they'll become this amazing athlete. And that's just not true. That's just a myth.

そうすれば、地球上のすべての人々に害を及ぼすことになる。人間性を奪ってしまうからだ。つまり、彼らがウルトラマラソンを走るとき、それは私がウルトラマラソンを走ろうとするときと同じくらい大変なことなんだ。彼らは汗をかき、苦労し、吐き気を催し、けいれんを起こす。彼らはそれが簡単だからやっているのではない。価値があるからやるのだ。彼らはそれをする価値があると思っている。そして、欧米の人たちを、何か自分たちが間違っているような、ひどい気分にさせるんだ。靴を捨てて、パレオダイエットをするとか。そうすれば突然、素晴らし

And so it's pernicious in a variety of ways. In 2012, I had the good fortune to be invited to go to the Ironman World Championships in Kona in Hawaii. It's an amazing event, right? And if you don't know what a full Ironman triathlon is like, you start off with a 2.4-mile open-water swim. Then the athletes rush out of the water, jump onto bikes with these high-tech helmets and stuff like that. They speed off, and they do a 112-mile bike ride across the desert. And then they come back, throw off their bike, jump off their bikes, and then they do a full marathon in the heat. It's like 90 degrees Fahrenheit, right? It's really amazing. And the elite athletes do this in a little bit over eight hours. They're just like cyborgs. They're not like human beings. It's astonishing to watch. And then the lesser athletes take longer to do, and everybody has to finish by 17 hours, so by midnight. It's just astonishing to see people put their bodies through that kind of endurance to achieve something like that. And I was really impressed by that. I'd never seen a full Ironman before. And then just a few weeks later, I was in a very rural part of Mexico, in Chihuahua, up in the Sierra Tarahumara, where I got to observe a rara hippery, which is the traditional foot race that the Tarahumara Native Americans do. And it's kind of almost like a soccer game. There are two teams, and they have a little ball, a little round ball that's carved out of wood that morning. And there are about five people on each team, and they kind of kick the ball with their feet and then chase it and find it and kick it again and chase it and find it and kick it again. There's like a little circuit they do, and there are two teams, and whichever team laps the other team wins. And the race I saw must have been about 40, 50 miles long. And so it's another incredible endurance event. And on the surface, you'd say, oh my god, these events are totally different. Ironman is very commercial, and everybody's wearing the fanciest, latest gear. And they've got super fancy shoes. They're using gel and goo and all kinds of specially formulated nutrition drinks. And their bikes cost like $10,000, $20,000.

だから、いろいろな意味で悪質なのだ。2012年、私は幸運にもハワイのコナで開催されたアイアンマン世界選手権に招待された。素晴らしいイベントでしょう？フルアイアンマントライアスロンがどのようなものかご存じない方は、まず2.4マイルのオープンウォータースイムから始まります。そして選手たちは水から上がり、ハイテクヘルメットなどを装着したバイクに飛び乗る。そして砂漠を112マイル自転車で疾走する。そして戻ってくると、自転車を投げ捨て、自転車から飛び降り、暑い中フルマラソンを走る。華氏90度くらいでしょ？本当にすご

And it's very commercial. And there are speakers and crowds, et cetera. Whereas the Tarahumara, when they're running, they're just wearing the clothes that they normally wear. They're running in sandals. It's very uncommercial. And you think, oh my gosh, it's so different. One is more authentic than the other. But if you stop and think, actually, they're very similar, right?

とても商業的だ。スピーカーもいるし、観衆もいる。一方、タラフマラ族は走っているとき、いつも着ている服を着ているだけだ。サンダルで走るんだ。とても非商業的だ。そして、あなたは、ああ、とても違う、と思う。一方は他方より本物だ。でも、立ち止まって考えてみると、実はとても似ているんだ。

Because both involve rewards, right? So Ironman, there's the winner, and the winner gets a prize, et cetera. Well, the Tarahumara also have prizes. They bet huge amounts of stuff, right? They bet clothes and goats and corn and stuff like that. They don't have Gatorade, but they make their own form of Gatorade out of corn. And they cheer on their runners, too. And there's the joy of victory and the agony of defeat and all that. So in some ways, they're very different. But in other ways, it's kind of the same thing. And it's a personal journey that people undertake, a very small number of them. The vast majority of people are observers. They're not participants.

どちらも報酬があるからでしょ？アイアンマンには優勝者がいて、優勝者には賞品が与えられる。タラフマラにも賞金がある。タラフマラには賞金もある。服とかヤギとかトウモロコシとか、そういうものを賭ける。ゲータレードはないけど、トウモロコシから独自のゲータレードを作るんだ。そしてランナーを応援するんだ。勝利の喜びもあれば、敗北の苦しみもある。だから、ある意味ではまったく違う。でも、ある意味では同じことなんだ。そしてそれは、ごく少数の人々が行う個人的な旅なんだ。大多数の人々は観察者である。参加者ではない。

So really, it made me realize that, oh, yes, there are some differences between more modern, commercialized Western forms of endurance physical activity. This is something basic and fundamental that all cultures do. And actually, I think what makes us similar is greater than what makes us different. There are different kinds of training, right? Play is a form of training, in a way, right? Children play, right? Because they're learning skills. They're developing capacities. And humans are one of the few species, dogs are another, that continue to play as adults, and that play helps us maintain our capacities. It helps us with social relationships. I mean, there's all kinds of good things that happen with play, right? But exercise is kind of very,

だから、近代的で商業化された西洋の持久的な身体活動には、いくつかの違いがあるのだ。これは、すべての文化が行っている基本的で基礎的なことだ。そして実際、私たちを似たものにしているものは、私たちを違うものにしているものよりも大きいと思う。トレーニングにはさまざまな種類がある。遊びはある意味、トレーニングの一種でしょう？子どもは遊びますよね？なぜなら彼らはスキルを学んでいるからだ。能力を開発しているんだ。そして人間は、犬もそうですが、大人になっても遊び続ける数少ない種のひとつです。遊びは私たちの能力を維持するの

I wouldn't say exercise is generally play, although some play is exercise. And when you kind of exercise in order to train for an event, you're doing something, you're spending a lot of energy, you're doing physical activity kind of to get ready for something, right? And certainly, you know, for the kinds of things that we do, again, that's a very modern Western behavior.

運動が遊びだとは一概には言えないが、遊びが運動であることもある。何かのイベントに向けてトレーニングするために運動するということは、何かをすることであり、多くのエネルギーを費やすことであり、何かを準備するために身体を動かすことなんだ。確かに、私たちがしているようなことは、非常に近代的な西洋の行動です。

So when I was talking to, and I've talked to Native American runners who participate in these long-distance races, when I asked them how they get ready for the race, how they train, they would kind of look at me like they didn't understand the question. There was, you know, what are you talking about? And so, you know, I was working with the translator. The translator was saying, you know, this gringo, he runs five miles every day to kind of get ready for a race.

だから、長距離レースに参加するネイティブ・アメリカンのランナーたちと話をしていたとき、彼らにレースの準備やトレーニングの方法を尋ねると、なんだか質問の意味がわからないというような顔をするんだ。何を言っているんだ？だから、私は通訳と一緒に仕事をしていた。通訳はこう言ったんだ、この外人は毎日5マイル走ってレースに備えるんだ、とね。

And, you know, the question that I got was, you know, why would you run if you didn't have to, right? Because their life is their training, right? You know, when I ask people there or ask people in Africa, in the places where I work, you know, like, when do you run? The most common answer I get is, oh, well, to chase a goat. You know, that's the most common answer I get.

そして、私が受けた質問は、「走る必要がないのに、なぜ走るんだ？なぜなら、彼らの人生は彼らのトレーニングだからだろう？アフリカの人々に尋ねたり、私が働いている場所の人々に尋ねたりすると、「いつ走るの？と聞くと、「ヤギを追いかけるとき」という答えが返ってくる。それが一番多い答えなんだ。

There are a lot of ways to quantify how physically active somebody is, right? And a very simple one, it's not necessarily the best one, but a simple way of doing it is what's called the physical activity level. It's just a ratio. So it's the total amount of energy you spend in a day divided by the energy you would spend if you were just in, you know, at bedrest, what's called your basal metabolic rates, the energy you spend just taking care of the most basic essential functions of your body. And so, say if you're in bedrest, you know, in a hospital and, you know, lying in bed with just like a clicker for the TV and you're doing absolutely nothing, not even digesting food, your physical activity level would be about, your power, physical activity level would be about a 1.2. And if you're like a Tour de France cyclist, it would be above 3. If you're kind of a desk worker, it would be like 1.6. So it's kind of a way to compare individuals but also species because it's standardized by how your body size, because your body size essentially determines your basal metabolic rate. And it's interesting that most animals have physical activity levels of about 2 to 3. So they're, you know, pretty active.

身体活動量を数値化する方法はたくさんありますよね。一番いい方法とは限りませんが、簡単な方法として、身体活動レベルというものがあります。これは単なる比率です。つまり、1日に使うエネルギーの総量を、ただ寝ているときに使うエネルギー、いわゆる基礎代謝率で割ったものです。例えば、病院で寝たきりで、ベッドに横たわり、テレビをクリッカーで見るだけで、何もせず、食べ物を消化することもしない場合、身体活動レベルは1.2程度になるでしょう。ツール・ド・フランスのサイクリストのような人なら3以上でしょう。デスクワーカーなら1

We evolved from apes and it turns out that primates in general and apes in particular have really low PALs, really low physical activity levels. Chimpanzees have physical activity levels of about 1.4. And so their physical activity levels are actually lower than sedentary Americans. So your average sedentary American who doesn't really do much and, you know, spends most of his or her time in chairs and, you know, etc. and takes elevators and all that is still more physically active actually than your average chimpanzee. Whereas hunter-gatherers, people who, you know, every day have to go out and get their food, their physical activity levels tend to be around 2, about, you know, 1.92. Or subsistence farmers who don't have a lot of machines and tractors and stuff like that, they're maybe a little bit harder working, maybe 2.1, 2.2. And it really, it wasn't until the industrial revolution that people's physical activity levels were able to go back, go down like about 25% to, you know, 1.6, 1.7, which is sort of typical of your average American. So it's a useful kind of simple standard to help us compare just generally how active different groups or different individuals are.

私たちは類人猿から進化し、霊長類全般、特に類人猿の身体活動レベルは本当に低いことが判明した。チンパンジーの身体活動レベルは約1.4である。チンパンジーの身体活動レベルは約1.4であり、彼らの身体活動レベルは座りっぱなしのアメリカ人よりも低い。つまり、平均的な座りっぱなしのアメリカ人は、たいしたことはせず、ほとんどの時間を椅子やエレベーターなどで過ごしているのだが、それでも平均的なチンパンジーよりは身体活動が活発なのだ。一方、狩猟採集民、つまり毎日外に出て食料を調達しなければならない人たちの身体活動レベルは

So your basal metabolic rate is a really important number because it tells you kind of just how much energy you're spending on just the essential maintenance of your body, you know, paying for your brain and paying for all the tissues in your body. And, you know, you have to turn over tissues all the time, like the cells in your gut are being replaced like every five days or so. I mean, your fingernails are growing. Everything's happening in your body, right? And that all costs energy. And it turns out that a kind of typical, say, adult male my size, right? I'm not all that big, but, you know, spends about two-thirds of his or her physical metabolism just on basal metabolic rate. So I spend about 1600 calories a day just existing, you know, just taking care of my body. So the vast majority of the energy that we spend isn't spent on running around and being physically active and moving. It's actually spent on just maintenance, just basic total maintenance. And that's one of the reasons why we kind of evolved not to be, you know, all that physically active when it wasn't necessary. Because until recently, energy used to be limited, right? It wasn't like, you know, 7-Elevens or Dunkin' Donuts or

基礎代謝量は本当に重要な数値で、脳や体内の全組織を維持するためにどれだけのエネルギーを費やしているかがわかるからだ。例えば、腸の細胞は5日おきくらいに入れ替わる。爪も伸びている。体内ではあらゆることが起こっているんだ。それにはすべてエネルギーが必要なんだ。そして、私のような体格の典型的な成人男性は、そうであることがわかった。僕はそんなに大きくないけど、基礎代謝量だけで身体代謝の約3分の2を費やすんだ。つまり、私は1日に約1600キロカロリーを、ただ自分の体を維持するために費やしているんだ。つまり、私たちが

Whole Foods or whatever your, you know, favorite place to get food is right around the corner.

ホールフーズでも何でも、あなたのお気に入りの食料調達場所がすぐ近くにある。

You know, if you wanted something to eat, you had to go find it. You had to either, you know, hunt it or gather it or dig it up. And so energy was limited. And when energy is limited, you have to engage in trade-offs, right? And so if you spend energy on physical activity, that means you're not spending energy on taking care of your body or reproducing, which is what the only thing natural selection really cares about. And so the fact that our bodies are so expensive helps explain why we tend to avoid unnecessary physical activity. Because it prevents, you know, like for example, this morning I went for a 5-mile run. So I spent about 500 calories. Those are 500 calories that I could have spent on my metabolism. And if I were energy limited, that would have been a bit of a problem, right? Which is why people who are energy limited and already physically active, it makes no sense for them to go for a needless, completely pointless 5-mile run in the morning. So technically, a calorie is the amount of energy it takes to raise one gram of water one degree centigrade. So it's a unit of energy. And so we convert various kinds of energy into calories. There are, of course, other units of energy, like the joule, for example. But calories are kind of a useful one because our food is labeled in calories. So a calorie is the most common one. But actually, the calories that we mostly talk about that are on our food labels are actually kilocalories. They're actually 1,000 calories.

何か食べたいものがあれば、それを探しに行かなければならなかった。狩るか、集めるか、掘り起こすしかなかった。だからエネルギーは限られていた。エネルギーが限られていれば、トレードオフをしなければならない。身体活動にエネルギーを費やすということは、身体のケアや繁殖にエネルギーを費やさないということであり、自然淘汰が本当に重視するのはそれだけなんだ。私たちの身体はとても高価であるという事実が、私たちが不必要な身体活動を避ける傾向にある理由の一助となっている。例えば今朝、私は5マイル走った。それで500キロカロリー

So when you look at a label for a chocolate bar or a can of beans or something, and it says there are 50 calories, it actually means that there are 50,000 calories, right? But anyway, that's neither here nor there. But that's fine. But so most of the time, we're talking about calories with a capital C or Kcal, kilocalories. And our bodies use a lot of calories. A typical human body spends about 2,000 to 3,000 calories or, in this case, kilocalories a day existing. That's your basal metabolic rate plus all the energy you spend running around, doing chores, making dinner, whatever it is you do for your day. When you go for a walk, you probably spend an extra 50 calories per mile. If you go for a run, you're spending probably an extra 100 calories per mile for that run. So that hopefully gives you a sense of what kind of energy amounts we're talking about.

だから、チョコレートバーや豆の缶詰などのラベルを見て、50キロカロリーと書いてあっても、実際は50,000キロカロリーもあるということなんだ。でも、それはどちらでもない。でも、それでいい。しかし、ほとんどの場合、私たちは大文字のCまたはKcal、キロカロリーのカロリーについて話している。私たちの身体は多くのカロリーを消費する。一般的な人間の身体は、1日に約2,000～3,000カロリー、この場合はキロカロリーを消費します。これは基礎代謝量に、走り回ったり、家事をしたり、夕食を作ったり、一日にするすべてのエ

Chapter two, smarter sitting, smarter sleeping. All right, so I'm sitting here talking to you.

第2章、よりスマートに座り、よりスマートに眠る。よし、私はここに座って君と話している。

But other than that, I'm basically doing nothing. Maybe I'm gesticulating a little bit, moving my mouth. But I'm completely physically inactive in any other regard. But even now, I'm spending a fair amount of calories just existing. And for every five breaths, one of my breaths is just taking care of my brain. My brain is constantly consuming vast quantities of energy. I spend about three, four, maybe 500, 450 calories a day just paying for my brain. My muscle, even if I'm not doing anything with my muscles, my muscles constantly require energy. My gut is requiring energy. My kidneys require energy. My liver is requiring energy. My heart is requiring energy.

でも、それ以外は基本的に何もしていない。少し身振り手振りをしたり、口を動かしたりしているかもしれない。でも、それ以外の点ではまったく身体を動かしていない。でも今でさえ、ただ存在しているだけでかなりのカロリーを消費している。呼吸5回につき、1回は脳のケアをしているんだ。私の脳は常に膨大なエネルギーを消費している。私は脳のために1日に3、4、あるいは500、450キロカロリーを費やしている。筋肉は、たとえ筋肉を使って何もしていなくても、常にエネルギーを必要としている。腸もエネルギーを必要とする。腎臓はエネルギ

My immune system, which is taking care of my body and making sure that I don't die from some virus or bacteria, that's taking up energy. So all of these processes are all adding up.

私の免疫システムは、私の体をケアし、私がウイルスやバクテリアによって死なないようにしている。つまり、これらすべてのプロセスが積み重なっているのだ。

And a typical human is spending about 1,300, 1,400, 1,500, 1,600 calories a day just on all those basic processes, even if they're doing nothing else. So just existing is a fairly expensive prospect. And we have unusually expensive bodies in one regard, which is that our brains are really big. So brains are extraordinarily expensive organs. My brain is about 2% of my body weight, but it's using something like a fifth of my metabolism at the moment. Because of all kinds of reasons, it's because there's lots of pumps that have to pump energy in and out of the brain, because I've separated my brain from my bloodstream with this barrier, and neurons are very expensive, and I'm synthesizing all kinds of neurotransmitters.

典型的な人間は、何もしていなくても、1日に1,300キロカロリー、1,400キロカロリー、1,500キロカロリー、1,600キロカロリーと、これらの基本的なプロセスに費やしている。つまり、存在するだけでもかなりお金がかかるのだ。私たちの脳は非常に大きい。つまり、脳は非常に高価な臓器なのだ。私の脳は体重の2％ほどだが、現在私の代謝の5分の1を使っている。いろんな理由があるんだけど、脳と血流をこのバリアで隔てているから、脳からエネルギーを出し入れするポンプがたくさんあって、神経細胞はとても高価で、いろんな神経

There's a whole bunch of things going on that make my brain super, super expensive.

いろいろなことが重なって、私の脳みそは超超高価になっているんだ。

And the thing about brains is that they don't store any energy. So unlike my muscles and my liver and other organs, which have some energy on board, all the energy from my brain constantly has to be delivered. And if I stop delivering that energy, even for just a short amount of time,

脳はエネルギーを蓄えることができない。だから、筋肉や肝臓や他の臓器がエネルギーを蓄えているのとは違って、脳からのエネルギーは常に供給されなければならない。そして、もし私がそのエネルギーを供給するのをやめてしまったら、たとえ短時間でも、

I'll die. So human brains, which are so big, require us to constantly have a little bit of extra energy on board. I decided to start this book on physical activity and exercise with actually discussing physical inactivity, because if you want to understand activity, you need to understand inactivity. There are as many myths about inactivity as there are about activity, and they illustrate, I think, how we make people exercise about health and about physical activity and other such things. And I think, for me, the most pernicious maybe is this idea that sitting is the new smoking. And it's a well-meaning expression. People who are public health experts who are trying to help people be more physically active, they think that by saying, trying to encourage people to get off the couch, get out of their chairs and be more physically active, that sitting is the new smoking as a way of doing that. And it's true that if you're never physically active, you increase your vulnerability to a wide range of diseases. But I think that the idea, that the concept kind of backfires because, look, I mean, the chair that I'm sitting in right now, I mean, it's not like a toxin like a cigarette, and it's not delivering poison to my bloodstream. It's just a completely harmless sort of thing. And furthermore, sitting is very normal. My dog spends most of her day just sitting around the house. If you go to any other part of the world, you go to villages all over the world, if you go to study hunter-gatherers, when they're not physically active, and we've already talked about how they're not physically active all day long, guess what they're doing? They're sitting. Now, they may not be sitting in chairs because they may not necessarily have chairs. They'll be sitting on the ground, or they might have benches or stools. But it turns out that when you measure amounts of sitting in non-Western, non-high-income populations, they sit pretty much as much as we do, about 10 hours a day. So I think we're not honest to people. Instead of saying sitting isn't you smoking and making people feel bad about themselves, why not tell them the truth, which is that there are better ways to sit and worse ways to sit. So it's good to be active when you sit, break up your sitting in bouts. Don't sit for huge amounts of time. Get up every once in a while. Make yourself a cup of tea, scratch the dog or something like that. And then the other is that there are more active kinds of sitting where you use some of your muscles. Right now,

死んでしまう。だから人間の脳はとても大きく、常に余分なエネルギーを搭載しておく必要があるのだ。身体活動と運動について書かれた本書の冒頭で、実際に運動不足について論じることにした。活動を理解したければ、運動不足を理解する必要があるからだ。運動不足については、活動に関する神話と同じくらい多くの神話があり、私たちがいかに健康や身体活動などについて人々に運動をさせているかを物語っていると思います。そして、私にとって最も悪質なのは、座っていることが新たな喫煙であるという考えです。これは善意の表現です。公衆衛生の専門

I'm sitting in this comfy chair, and it's stabilizing my back. I don't have to spend any energy. But if I was sitting on a stool or squatting on the ground, I would have to spend some muscles to keep my body going. And all of that just turns on the cellular engine of our body. It's like turning on the car engine. It causes you to use up some of the sugar in your blood. It uses up some of the fats in your blood. It turns on various kinds of genes. It's all good, right? So you don't have to exercise hugely to get some of the benefits of being a little bit more active. Just moving a little bit is actually kind of healthy. And furthermore, when you look at the data on sitting, it turns out that how much you sit at work isn't really that much associated with health outcomes. It's how much people sit in leisure time that's associated with negative health outcomes. So if you sit all day at work, and then you go home, and you sit all day, and you're driving to work, and you're driving home, and you basically never do any physical activity, well, yeah. Then your risk of a wide range of diseases goes up. But if you have a normal desk job, but you also walk around and get some exercise and do various stuff, you're fine.

この快適な椅子に座っていると、背中が安定するんだ。エネルギーを使う必要がない。でも、もしスツールに座ったり、地面にしゃがんだりしたら、体を動かすために筋肉を使わなければならない。そしてそのすべてが、私たちの身体の細胞エンジンをオンにするだけなのだ。車のエンジンをかけるようなものだ。血液中の糖分を消費する。血液中の脂肪を使い切る。さまざまな遺伝子をオンにする。いいことずくめだろ？だから、激しい運動をしなくても、少し体を動かすだけで効果があるんだ。ちょっと動くだけで、実は健康にいいんだ。さらに、座っていること

There's no evidence that there's any problem with that. It's a completely normal thing to do.

それが問題だという証拠は何もない。まったく普通のことだ。

So I got interested in the myths about sleep because we're told all the time to sit less, but then we're also told to sleep more. Why is that? What's going on there? And one of the myths about sleep, which is, of course, one of the most fundamental forms of physical inactivity is sleeping, is that the modern Western world has robbed us of sleep. We have television and iPhones and electric light bulbs and all these sorts of things. And ever since Edison, nobody's been able to sleep very much. And yet, I've spent time in various parts of the world where there's no electricity, and people seem to be up all night. I've always wondered about that. And I was delighted to see that there's been some research recently on that. This is not my research, where people have shown that in parts of the world, and we're talking about multiple continents, we're talking about Africa and South America and North America, places where people don't have electricity, people don't sleep eight hours a night. They actually sleep five and a half, six, sometimes seven hours a night. And so there's no evidence whatsoever that people sleep less in the modern industrial world because of televisions and iPhones and stuff like that.

だから、睡眠に関する神話に興味を持ったんだ。僕たちはいつも、座る回数を減らすように言われるけど、その一方でもっと眠るようにも言われる。なぜだろう？そこで何が起こっているのか？睡眠に関する神話のひとつは、もちろん、運動不足のもっとも基本的な形態のひとつが睡眠である。テレビ、iPhone、電球、その他いろいろなものがある。エジソン以来、誰もあまり眠ることができなくなってしまった。それなのに、私は電気が通っていない世界各地で過ごしたことがあるが、人々は一晩中起きているようだ。いつも不思議に思っていたんだ。そして

And then furthermore, when you look at the epidemiological data, so you look at how much people sleep, and not just what they say they sleep, but how much they actually sleep using sensors, because who knows actually how much they slept? How can you know that you're asleep?

さらに、疫学的なデータを見てみると、人々がどれくらい寝ているのか、そして、単に寝ていると言うだけでなく、センサーを使って実際にどれくらい寝ているのかを見ている。自分が眠っていることをどうやって知ることができるのか？

But if you measure sensor-based data on how much people sleep against their health outcomes on the y-axis, it turns out it's a U-shaped curve. And the bottom of that curve, so the optimal amount of sleep, turns out to be, for most people, around seven. Now, it's not a law. There's some people who do better with eight, and some people better with six, et cetera. But seven turns out to be better than eight for most people. So where this idea that we all need eight hours of sleep is,

しかし、人々の睡眠時間に関するセンサーベースのデータをY軸の健康結果に対して測定すると、U字型の曲線になることがわかった。そして、その曲線の底、つまり最適な睡眠時間は、ほとんどの人にとって7時間前後であることがわかった。ただし、これは法則ではない。8時間のほうがいい人もいれば、6時間のほうがいい人もいる。しかし、ほとんどの人にとって、8よりも7の方が良いことが分かっている。つまり、8時間の睡眠が必要だという考え方はどこにあるのか、

I think, pernicious. Now, it's true. It is definitely true that if you don't get enough sleep, you are compromising your health. If you're getting three or four hours of sleep, and you're constantly exhausted, and you fall asleep all the time, that's an issue. And it's worth paying some attention to that. But then just making people feel bad about their sleep, if they're actually getting normal amounts of sleep, just makes them anxious. It makes them concerned. And of course, when you make somebody anxious about sleep, what do you do? You arouse them. You elevate their levels of cortisol, which is a stress hormone. And guess what cortisol does?

悪質だと思う。さて、それは事実だ。十分な睡眠を取らないと健康を損なうというのは間違いなく事実です。睡眠時間が3、4時間で、常に疲れ切っていて、いつも眠りについているとしたら、それは問題です。そのことに注意を払う価値はある。しかし、実際には普通の睡眠時間をとっているにもかかわらず、睡眠を悪く思わせることは、人々を不安にさせるだけだ。不安にさせるだけだ。もちろん、睡眠に不安を抱かせたら、どうするか？興奮させるのだ。ストレスホルモンであるコルチゾールのレベルを上昇させるのだ。コルチゾールは何をすると思う？

It keeps you from sleeping. So making people kind of nervous about their sleep sets in motion, or can set in motion, a kind of vicious circle where you make people feel bad about their sleep. And then because of that, they're less likely to sleep. And it kind of drives a positive feedback loop. And so look, we should relax about sleep. We should help people more compassionate. If people aren't getting enough sleep, let's help them figure out ways to get sleep. And do that by treating the cause, not the symptoms of the lack of sleep.

眠れなくなる。つまり、睡眠に対して神経質になることで、睡眠に対して嫌悪感を抱かせるという悪循環に陥ってしまうのです。そして、そのせいで眠れなくなる。そして、それが正のフィードバックループを引き起こす。だから、私たちは睡眠についてリラックスすべきなのです。もっと人を思いやるべきだ。十分な睡眠がとれていないのであれば、睡眠をとる方法を見つける手助けをしよう。そして、睡眠不足の症状ではなく、原因を治療することで、それを実現しよう。

But let's not make people stressed about it in ways that are unhelpful.

しかし、そのことで人々にストレスを与えるようなことはやめよう。

If you want to look at the power of culture and affecting biology, sleep is such a great example.

文化が生物学に与える影響力を見るなら、睡眠はその好例だ。

Because in places like America, Western countries, we have such culturally prescribed ways of sleeping that would baffle our ancestors and baffle people in other parts of the world.

というのも、アメリカや西洋諸国では、私たちの祖先や他の地域の人々を困惑させるような、文化的に規定された睡眠方法があるからだ。

We have this idea that sleep is this sort of solitary thing you do in a dark room with no noise and a super comfortable mattress. And we get upset if we hear a car honking or a dog barking or whatever. But for most of human evolution, in many cultures, sleep is a very social thing.

私たちは、睡眠とは真っ暗な部屋で、騒音もなく、寝心地のいいマットレスでする孤独なものだという考えを持っている。そして、車のクラクションや犬の鳴き声などが聞こえると動揺する。しかし、人類の進化の大半において、多くの文化において、睡眠は非常に社会的なものだった。

People sleep in groups. And you're outside and you hear animals in the distance. And actually hearing them in the distance is maybe a good thing because it helps your brain realize that they're in the distance. They're not nearby. And people sleep on the ground. They don't need to sleep in mattresses. And they don't have fancy pillows and all that kind of stuff. And you can learn to sleep in all kinds of situations if you relax, if you allow yourself. And the fact that we kind of feel like we have to have this sort of special circumstances. I'm no different. I like a nice quiet room and a comfortable mattress and all that sort of stuff. But I do try to remind myself when I have trouble sleeping that you can sleep on an airplane. You can sleep in a chair in a lecture when it's boring. I can sleep in all kinds of crazy places. And I can certainly sleep in this bed tonight if I want to. It's just a question of my mindset, not the environment that

人々は集団で眠る。外にいると、遠くから動物の鳴き声が聞こえる。遠くで動物の鳴き声が聞こえるのは、脳が動物が遠くにいることを認識するのに役立つからだ。近くにいるわけではないのだ。人は地面で眠る。マットレスで寝る必要はない。高級な枕やそういうものもない。リラックスすれば、どんな状況でも眠れるようになる。私たちは特別な環境でなければならないと思っている。私も同じだ。静かな部屋とか、寝心地のいいマットレスとか、そういうものが好きなんだ。でも、眠れないときは、飛行機の中でも眠れるということを思い出すようにしている。

I'm in. Chapter 3. Walking, running, and everyday strength. Humans really suck at speed. I mean, there's just no way around it, right? I mean, as soon as we became bipedal, which was a great thing in some ways, right? About 7 million years ago, probably to save energy when we were walking.

私も第3章歩くこと、走ること、そして日常の強さ人間は本当にスピードが苦手だ。つまり、どうしようもないんだよね。つまり、人間が二足歩行になった途端、それはある意味素晴らしいことだったんだ。約700万年前、おそらく歩くときのエネルギーを節約するためだろう。

And it helps us carry things and we can have tools and we can gesticulate in ways that quadrupeds can't. Lots of great things about being a biped. But the second we get up on two legs, we lose half our horsepower, right? We only have two legs to generate power as opposed to four.

四足歩行ではできないような身振り手振りもできる。二足歩行には素晴らしい点がたくさんある。しかし、2本足で立ち上がった途端、馬力の半分が失われるんだ。パワーを生み出す足が4本に対して2本しかないんだ。

And so we're about half as fast as a quadruped, our size. And that's true for the world's best runners. So Usain Bolt, who still owns the world record in the 100 meters, he can run a little bit over 10 meters a second, right? He can run, I think, 10.4 meters a second.

だから、私たちの体格では四足歩行の動物の約半分のスピードしか出せない。それは世界のトップランナーにも言えることだ。100メートルの世界記録を持つウサイン・ボルトは、秒速10メートルちょっとで走ることができる。確か秒速10.4メートル。

Your average goat from a pen just down the street can run 20 meters a second, and for a lot longer than Usain Bolt, right? So humans in general are slow, even the fastest humans on the planet.

通りを一本入ったところにいる平均的なヤギは、1秒間に20メートル走ることができるし、ウサイン・ボルトよりもずっと長い時間走ることができるだろ？つまり、地球上で最も足の速い人間でさえ、一般的に人間は遅いのだ。

And so we have this idea that humans evolved for running, but not for sprinting, but more for endurance running. And so there's this general idea out there that there's a trade-off between speed and endurance, and that you can either be really fast and not go very far, or can be slow and you can go forever. And we all know that's kind of true. But at the elite levels, it's especially true in terms of performance. But for most of us, actually, if you want to improve your endurance, one of the best ways to do that is actually to work on your speed, do what we call interval training. Occasionally get around, do some track work, do 200, 400, 600 meter repeats.

人類は走るために進化したが、短距離走のためではなく、持久的な走りのために進化したという考え方がある。スピードと持久力はトレードオフの関係にあり、スピードが速くても遠くまで行けないか、遅くても永遠に走り続けられるかのどちらかだ。そして私たちは皆、それが真実であることを知っている。しかし、エリートレベルでは、パフォーマンスという点で特にそうだ。しかし、ほとんどの人にとって、持久力を向上させたいのであれば、実はスピードを鍛えること、いわゆるインターバル・トレーニングをすることが最善の方法のひとつなのだ。たまにト

That'll not only make you faster, it'll also improve your endurance. But we often think about this trade-off because of the world's best athletes, right? And I think it shows how we get kind of off track by focusing too much on elite sports and professional athletics. So Usain

そうすれば速くなるだけでなく、持久力も向上する。しかし、私たちはしばしばこのトレードオフについて考える。そして、エリートスポーツやプロの陸上競技に集中しすぎることで、私たちがいかに道を踏み外しているかを示していると思います。ウサイン

Bolt, he can run like 10.4 meters a second for like 10, 20 seconds, but he can't run a marathon at that distance. The world's record holder at the moment for the marathon is a guy named Elliot

ボルトは秒速10.4メートルで10秒とか20秒とか走れるけど、その距離でマラソンは走れない。現在、マラソンの世界記録保持者はエリオットという男だ。

Kipchoge, fantastic runner too. And he can run a 440 mile, that's like six meters a second, a little more than six meters a second for 26 miles, which is astonishing. But I can't do that for one mile, right? And so you look at Bolt and Kipchoge and you think, okay, this guy's running almost twice as fast as the other guy, there's a trade-off between speed and endurance. But for most of us, actually, we can run, people can run, as I said before, if you want to run longer distances, one of the best ways to do that is to increase your speed. And people who are good at speed tend to also be better at endurance, unless they're elite athletes. So if you look at decathletes, for example, people who are amateur decathletes, the ones who are really good at the speed events are also good at the endurance events. So that trade-off is true only for really elite athletes.

キプチョゲも素晴らしいランナーだ。彼は440マイルを走ることができるんだ。1秒間に6メートル、26マイルを走るのに1秒間に6メートルちょっと、これは驚異的だよ。でも、私には1マイルも走れない。ボルトやキプチョゲを見て、この選手は他の選手より2倍も速く走っている、スピードと持久力はトレードオフの関係にある、と思うだろう。しかし、私たちのほとんどは、実は走ることができるのだ。スピードが得意な人は、エリート選手でない限り、持久力にも優れている傾向がある。だから、例えばアマチュアの十種競技の選手を見てみると、スピ

It's not really true for the vast majority of us. So strength is important. And I think, and there are misconceptions about strength too. So strength is the ability, how much force you can produce, right? And power is the rate at which you can produce that force. So you can be, you don't need a lot of, you can be really strong, but not actually necessarily all that powerful, right? And so people who aren't all that strong, you know, if I were to get out of this chair, that requires power. I have to rapidly push my body up, right? And one of the problems that happens in the world today is that people get really frail as they get old. They lose strength.

私たちの大多数にとってはそうではない。だから強さは重要なんだ。そして、強さについても誤解があると思う。筋力とは能力であり、どれだけの力を生み出すことができるかということですよね？そしてパワーとは、その力を生み出す速度だ。だから、力がなくても、本当に強くても、実はそれほどパワフルでなくてもいいんだ。だから、それほど強くない人が、この椅子から立ち上がるとしたら、それにはパワーが必要なんだ。体を急激に押し上げなければならないんだ。今の世の中で起きている問題のひとつは、年を取ると本当に体が弱くなるということだ。力

So hunter-gatherers aren't super strong. They tend to be about 75th percentile for sort of standard measures of strength, like, you know, grip strength tests. So, you know, they're, you know, like 25% of Americans would be stronger than your average hunter-gatherer, right? So they're not super strong. They're strong, but they're not, like, crazy strong.

狩猟採集民はそれほど強くない。標準的な筋力測定、例えば握力テストなどでは、75パーセンタイルくらいです。つまり、アメリカ人の25％は平均的な狩猟採集民よりも強いということだ。だから、彼らは超強いわけではない。強いけど、めちゃくちゃ強いわけじゃない。

But the difference is that as they age, they stay strong. So Americans, as we get older, or Brits, as they get older, you know, the strength declines rapidly. By the time people are in their 60s and 70s, they're pretty frail. But hunter-gatherers remain fairly physically active as they age because they're doing stuff. You know, they don't have can openers. They have to, you know, they don't have jars anyway, but they're, you know, they have to lift things and carry things and do stuff that keeps them strong. And the end result is that they maintain that strength. And that strength is important because one of the real serious, most pernicious issues of aging is a disease, or it's a problem called sarcopenia. Sarco is flesh, and penia is loss.

でも違うのは、彼らは年を取っても強さを保つということだ。アメリカ人は年を取るにつれて、イギリス人は年を取るにつれて、体力が急速に衰えていくんだ。60代、70代になると、かなり弱ってくる。でも狩猟採集民は、歳を取ってもかなり体を動かしている。彼らは缶切りを持っていない。でも、物を持ち上げたり、運んだり、体力を維持するためにいろいろなことをしなければならない。その結果、体力を維持することができる。なぜなら、加齢に伴う深刻で悪質な問題のひとつに、サルコペニアという病気があるからだ。サルコは肉、ペニアは喪失。

So it's flesh loss. And as people get older in the West, they tend to lose a lot of strength and power. And that makes basic tasks difficult, like getting out of a chair, you know, going to the bathroom, you know, climbing the stairs, you know, doing chores, you know, going to the store. And when that happens, people become less active. When they become less active, they become less fit, and it kind of sets in motion a really disastrous, vicious cycle, right? And so as we get older, strength training becomes more and more important so that we can avoid those losses of vigor that are really important to maintaining your health and staying strong and staying healthy as we age.

つまり、肉体の衰えだ。欧米では年を取るにつれて、体力や筋力が低下する傾向にある。椅子から立ち上がる、トイレに行く、階段を上る、家事をする、買い物に行くなど、基本的な作業が困難になる。そうなると、人は活動的にならなくなる。運動量が減ると、体格も悪くなり、悲惨な悪循環に陥ってしまうんだ。年をとるにつれて、筋力トレーニングはますます重要になってくる。そうすれば、健康を維持し、年をとっても丈夫で健康でいるために本当に重要な、活力の低下を防ぐことができる。

I mean, every culture engages in sports, right? It's a human universal. And sports are important for, and they're fun, and they're kind of play, right? And they serve all kinds of functions.

つまり、どの文化圏でもスポーツをするでしょ？それは人間の普遍的なものだ。スポーツは重要だし、楽しいし、一種の遊びだろ？そして、あらゆる種類の機能を果たす。

And sports are socially important, especially when you're children, you learn good sportsmanship, right? You learn not to, if somebody scores a goal on you, it's not appropriate to bash them in the face, you know, that sort of thing. You learn to be, you know, you learn hierarchies, you learn companionship, you learn how to cooperate. There's a lot of wonderful things about being on a team and sports and all that. But some sports also have another origin, which is, I think, to train warriors. It's not coincidental that a lot of the sports, for example, in the Olympics, think about the ancient Olympics especially, were skills that were really important for warriors, right? You know, javelin throwing and chariot racing. Well, we don't do chariot racing anymore. You know, sprinting, wrestling, boxing, right? These are all very kind of physically demanding sports that are kind of combat related, right? So sports have all kinds of different meanings. And of course, the problem is that not everybody enjoys sports, and not all sports are all that physically active. I mean, take baseball, for example, which is a perfectly wonderful game. But I call it a game, not a sport, because you don't really have to be that physically active to play baseball. You have to have incredible reflexes. I mean, it takes a lot of skill to be a great baseball player. But, you know, it's not, you know, maybe if you're stealing bases, you have to be fast. But the vast majority of baseball players don't really actually have to engage in that much physical activity, right? And that's not a criticism of baseball. It's just that let's not equate all sports with physical activity. And I think that kind of an interesting dimension of sports that we never really think about that much is that sports, I think, evolved also to help us learn not to be reactively aggressive. So there's two kinds of aggression. There's reactive aggression. So like, you know, you figured it, like, take my watch, I'd like to be really mad at you, and I might hit you, right? But, you know, that's kind of an instant kind of non-planned, you know, aggression. But, you know, road rage is a perfect example of reactive aggression. But there's also proactive aggression, right? Which is when you plan something, you know, premeditate, you work it out in advance, right?

スポーツは社会的に重要だし、特に子供の頃はスポーツマンシップを学ぶだろ？誰かにゴールを決められても、相手の顔を殴ったりしてはいけないとか、そういうことを学ぶんだ。上下関係も学ぶし、協調性も学ぶ。チームやスポーツの素晴らしさはたくさんある。しかし、スポーツにはもうひとつの起源がある。例えば、オリンピックの多くの競技が、特に古代のオリンピックを考えてみると、戦士にとって本当に重要な技術であったことは偶然ではないだろう。槍投げとか、戦車レースとかね。今はもう戦車レースはやっていないけどね。短距離走、レスリング、

And war is an example of a proactive aggression. I think sports are also kind of proactive aggression sometimes. And in a lot of sports, we teach people not to be reactively aggressive.

戦争は積極的な侵略の一例だ。スポーツもまた、時には積極的な攻撃性の一種だと思う。多くのスポーツでは、反応的に攻撃的になってはいけないと教えている。

I mean, the extreme to me is tennis, right? You're not even allowed to swear when you're playing tennis, right? But it's perfectly acceptable to be appropriately, proactively aggressive, as long as you're within the rules, right? And that's what humans excel at. We excel at curbing our reactive aggression. And we excel in many cultures, and the US is no exception, at being really good at proactive aggression. That's what we call war.

つまり、私にとって極端なのはテニスでしょ？テニスをしているときに悪態をつくことさえ許されないでしょ？でも、ルールの範囲内であれば、適切に、積極的に攻撃的になってもまったく問題ないでしょ？そしてそれこそが、人間が得意とすることなのだ。私たちは反応的な攻撃性を抑えることに長けている。そして、多くの文化において、そしてアメリカも例外ではなく、積極的な攻撃性に長けている。それが戦争と呼ばれるものだ。

I like to try participant observation. You know, I like to try what I study, right? You know,

私は参加者観察を試すのが好きなんだ。自分の研究したことを試してみたいんだ。わかるでしょ？

I like to try barefoot running, and I like to eat foods that other people eat. And when I was working on this chapter on aggression, I realized, you know, I'm a very unaggressive person.

裸足で走るのも好きだし、他の人が食べるものを食べるのも好きだ。そして、この「攻撃性」の章を執筆しているとき、私はとても攻撃的でない人間だと気づいた。

And I didn't want to, like, you know, go participate in some kind of brawl in a bar or something like that. But I thought, I'll go to a mixed martial arts fight. That's like, you know, because I've never been to one before. You see them on TV, but it's not the same thing.

それに、バーで乱闘騒ぎみたいなものに参加したくはなかったんだ。でも、総合格闘技の試合を見に行こうって思ったんだ。今まで一度も行ったことがなかったから。テレビでは見るけど、それとは違う。

So I went to a mixed martial arts fight, not too far from Boston. And it was a fascinating experience to see, you know, how people, because, you know, mixed martial arts, there are really almost no rules, you know, you're not allowed to kick somebody in the groin, you're not allowed to bite them. And if somebody wants to stop, you know, if they're in peril, you have to stop. But that's about it. There's not a lot of other rules, right? And, you know, apart from a few, you know, fights when I was in school, when people, you know, bullies, you know, hit me and stuff like that. I mean, I've never really, you know, seen a lot of fighting in my life. I've kind of cloistered life. So it was fascinating to go see these mixed martial arts fights and see how people can be, you know, how humans fight. Because, you know, we're as a species, you know, we do fight hand to hand, but most of the fighting that humans do is with weapons, right? You know, we've invented weapons millions of years ago. And it's kind of strange to see people willingly fight each other without the benefit of weapons, right? And what it really shows is just how bad we are as a species, how inadequately adapted we are for combat without weapons. You know, we really are adapted for fighting with weapons. You know, we don't have claws. We don't have fangs. We're bipedal. So we have these big heads that are very vulnerable.

それで、ボストンからそれほど遠くない総合格闘技の試合を見に行ったんだ。総合格闘技にはルールがほとんどないから、相手の股間を蹴ってはいけないし、噛んではいけない。誰かが止めたいと言ったら、その人が危険な状態なら止めなければならない。でも、それだけだ。それ以外のルールはあまりないよね？学生時代に、いじめられっ子に殴られたりして喧嘩したことを除けばね。つまり、僕の人生で喧嘩をたくさん見たことはないんだ。隠遁生活を送ってきたんだ。だから、総合格闘技の試合を見に行って、人間の戦い方を見るのは魅力的だった。というのも

And so it's really kind of fascinating to see how human fighting is really so different from the way animals fight. You know, going to see a mixed martial arts fight really kind of, at least for me as somebody who's thinking about it from an evolutionary and anthropological perspective, just how much weapons have changed the nature of human aggression. If there's any one physical activity that humans evolved to do, it's to walk. We are the walking champions of, you know, among the world. I mean, we're just, you know, walking is the most fundamental basic form of human physical activity. We know from studies of hunter-gatherers in tropical environments, you know, there's not just one group of people, but people from different parts of the world, that women on average walk about nine kilometers or five miles a day. And men walk on average about 14, 15 kilometers a day, about nine to 10 miles every single day, right? They do it seven days a week. There are no holidays. There's no weekends. There's no retirement. Walking is the way in which humans get around, get food. You know, it's kind of fundamental to who we are as a species.

だから、人間の戦い方が動物の戦い方とどう違うのかを見るのは本当に魅力的なんだ。総合格闘技の試合を観に行くと、少なくとも進化学や人類学の観点から考えている私にとっては、武器が人間の攻撃性の本質をどれほど変えてしまったかがよくわかる。人類が進化してきた身体活動があるとすれば、それは歩くことだ。私たちは歩くことのチャンピオンなのだ。つまり、歩くことは人間の身体活動の最も基本的な形態なのだ。熱帯地域の狩猟採集民の研究から、女性は1日に平均約9キロ、5マイル歩くことが分かっている。男性は1日平均約14～15キロ、9

We often carry when we walk. And today, in the modern sort of Western world with cars and escalators and elevators and, you know, Zoom and, you know, TV and all that sort of stuff, we just don't walk very much. So especially during this pandemic, people have been walking, you know, step counts have plummeted around the world from already pretty low levels. So, you know, the average sort of hunter-gatherer will take maybe, you know, 10, 15,000 steps a day.

私たちは歩くときによく荷物を運ぶ。そして今日、車やエスカレーター、エレベーター、ズーム、テレビ、その他もろもろのものがある近代的な西洋世界では、私たちはあまり歩かない。だから、特にこのパンデミック（世界的大流行）の間、人々は歩き続けてきた。狩猟採集民の平均的な歩数は、1日に1万歩から1万5千歩程度でしょう。

The average American before the pandemic was taking something like 4,700 and something steps a day. So a lot less than our ancestors. And, you know, my step counter for the, you know, when I'm not running, you know, my discount running, I mean, my steps have decreased by about 50% during this pandemic, during COVID, because, you know, I'm not going anywhere.

パンデミック以前の平均的なアメリカ人は、1日に4,700歩かそこら歩いていた。私たちの祖先よりもずっと少ない。私の歩数カウンターを見ると、走っていないとき、つまりランニングをしていないときの歩数は、このパンデミックの間、COVIDの間、約50％減少している。

You know, I'm traveling to the bathroom and occasionally, you know, I go on a little errand here or there and I walk the dog around the block. But that's about it, right? And one of the misconceptions that, and it's a bit of a debate right now, but people often sort of discount how important walking is because people think that walking really isn't very good for weight control and weight loss. And I would disagree with that. I think it's to be sure that if you walk only, you know, a few miles a day, you're not going to lose very much weight very fast. It's, you know, you don't spend that much energy walking. So if you want to go on a, if you want to lose weight, you know, not eating, you know, bacon or cheese or, you know, other things that are really, you know, sugary things that are full of calories, you're going to go, you're going to lose a lot more calories than if you walk for a few miles, right? But walking is important because even if you do a fair amount, you still will actually lose some weight. You'll just lose small amounts and you'll lose it slowly, but that's still good. But more importantly, walking is, turns out to be an important way to kind of keep your metabolism going to prevent weight gain. And there's a lot of studies which show that physical activity, you know, it's not the best way to lose weight, but it is an important component of preventing people from gaining weight or regaining weight after a diet. So if people go on a diet and then they lose weight and then they stop the diet, they often regain the weight. It's very common. But people go on a diet, lose weight, and then they stay physically active, they're much more likely to keep that weight off. Again, one of the ways which we medicalize exercise in the Western world is we think there's a certain amount you should do, right? We prescribe it, you know? You should have, you should take two aspirin, you should get eight hours of sleep, and you should walk 10,000 steps a day. You know, we like that, right? And there's nothing necessarily wrong with a goal, right? Goals can be really helpful, actually. But 10,000 steps is kind of arbitrary, right? The number actually came from when the first pedometer was invented in Japan before the 1960s Olympics. They were, you know, in the board room, they were trying to decide what to call it. Turns out that 10,000 is a very auspicious number in Japan. And they thought it kind of sounded good. It seemed kind of reasonable. So they called it, you know, 10,000 step monitor. And that kind of stuck. And surprisingly, it turns out that 10,000 steps isn't actually a bad goal, right? It's, if you actually look at what, you know, a lot of, you know, people in non-Western societies do, you know, 10,000 steps isn't actually that far off.

トイレに行ったり、たまにちょっとした用事で犬を散歩させたり。でも、それだけでしょう？今、ちょっと議論になっていることなんですが、ウォーキングがいかに重要か、よく誤解されているんです。私はそうは思いません。1日に数キロしか歩かないのであれば、すぐに体重が減るわけではありません。歩くのにそんなにエネルギーを使わないからです。だから、体重を減らしたいのなら、ベーコンやチーズや、カロリーの高い甘いものを食べないようにすれば、数キロ歩くよりもずっとカロリーを減らせるんだ。でも、ウォーキングは重要なんだ。少量ずつ、ゆ

So it's a perfectly reasonable goal to shoot for. But there's nothing, like, special about it.

だから、目指すべき目標としてはまったく妥当だ。でも、特別なことは何もない。

If you do 8,000 steps, that's fine. If you do 15,000 steps, that's fine. The important thing is to get, you know, get, be physically active because some is better than none. And a little bit more is, you know, tends to be better than that. But, you know, it's all good. You know, there's no magical number. There's no, it's not a U-shaped curve with a, you know, a bottom on it, right, where that tells you, like, where you should aim for. That doesn't, that does not exist.

8,000歩ならいい。15,000歩でもいい。大切なのは、体を動かすことだ。少しでも多い方がいいに決まっている。でも、それがいいんだ。魔法の数字はないんだ。U字カーブのように底があるわけでもない。そんなものは存在しない。

I'm especially interested in running. It's actually one of my major areas of research. And

私は特にランニングに興味がある。実は私の主要な研究分野の一つなんだ。そして

I'm interested in how humans evolved to run long distances and what role running plays in our, in our, in our lives and in our evolution. And look, running is the most fundamental form of vigorous physical activity. Walking is the most fundamental form of moderate activity. Running is what we do to be vigorous, right? You know, because there were no ellipticals and, you know, other kinds of machines back in the Stone Age. If you want to get your heart rate up, you probably were running, right? And people ran long distances in order to hunt or scavenge, etc.

私は人類がどのように長距離を走るように進化してきたのか、そしてランニングが私たちの生活や進化においてどのような役割を果たしているのかに興味がある。ランニングは活発な身体活動の最も基本的な形態である。ウォーキングは中程度の活動の最も基本的な形だ。ランニングは、私たちが精力的に活動するために行うものだ。石器時代にはエリプティカルや他の種類のマシンはなかったからね。心拍数を上げたいなら、おそらく走っていただろう？狩りをしたり、食料を調達したりするために、人々は長距離を走ったんだ。

But running today is kind of, you know, a very popular sport, way to exercise. And a lot of sports use a lot of running. You know, a typical soccer player will run, you know, five, six miles in a game. So, so running is, there's a lot of ways in which people run. And, but, but, but people are kind of exercised about running too, like there are so many other kinds of physical activity.

しかし、今日、ランニングは非常にポピュラーなスポーツであり、運動方法だ。多くのスポーツがランニングを多用している。典型的なサッカー選手は、1試合で5、6マイル走る。だから、ランニングは、人が走る方法はたくさんある。でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、でも、みんなランニングのことをよく考えている。

And one of the biggest myths about running is that it'll destroy your knees. And, and like all myths, this is a bit complicated, because it is true that the most common injuries that runners experience are knee injuries, right? But there are kind of two kinds of knee injuries. Some knee injuries are caused by, you know, by your muscles being kind of out of whack, and, you know, you kind of pull a ligament or you pull a tendon or something like that, or your IT band, etc.

そして、ランニングに関する最大の神話のひとつは、膝を壊すというものだ。そして、他の神話と同じように、これは少し複雑なのですが、ランナーが経験する最も一般的な怪我が膝の怪我であることは事実です。しかし、膝の怪我には2種類ある。ある膝の怪我は、筋肉が異常をきたして、靭帯を引っ張ってしまったり、腱を引っ張ってしまったり、ITバンドを引っ張ってしまったりすることで起こります。

But those are injuries that you can recover from. And the other kind of injury are wear and tear injuries, which you can't recover from, the worst being osteoarthritis. And the idea that running too much wears out your joints is just wrong. It's just fundamentally, completely wrong.

しかし、それらは回復できる怪我だ。もうひとつの怪我は消耗によるもので、これは回復できない。走りすぎると関節がすり減るという考えは間違っている。根本的に、完全に間違っている。

You know, it's like, you know, if you think about your joints, like the shock absorber in your car, it's just like, it's just nonsense. There's tons and tons of studies, more than a dozen, randomized, controlled, perspective, gold standard studies, which show that people who run more are not more likely to get arthritis. In fact, lots of research shows, and research from my lab among them, that physical activities like running actually cause your joints to repair themselves and to stay healthy. The other kinds of running injuries, so you're not going to destroy your knees by running, at least in terms of arthritis. But if you have arthritis and you run, it can be excruciating. You can exacerbate it. The other kinds of running injuries, I think that a lot of them are caused because people, we don't learn how to run properly anymore. I think running is a skill, right? Like swimming or throwing or, you know, all kinds of other things that we do. And we don't learn the skill that much of running anymore in the Western world. But the cultures

関節を車のショックアブソーバーのように考えるのはナンセンスだ。たくさんの研究があるんだ。ランダム化された、対照的な、観点からの、ゴールドスタンダードな研究が10以上あるんだ。実際、多くの研究が示しており、私の研究室でも、ランニングのような身体活動は実際に関節を修復し、健康な状態を維持することを示している。他の種類のランニングによる怪我は、少なくとも関節炎という点では、ランニングによって膝を破壊することはありません。しかし、もしあなたが関節炎を患っていて、ランニングをするのであれば、それは耐え難いものでしょ

I work in, like, you know, you ask people about running, they believe that it's a skill and that there's like a right way to run and a wrong way to run. And how do they learn the right way to run?

私はランニングの仕事をしているが、ランニングは技術であり、正しい走り方と間違った走り方があると信じている。どうやって正しい走り方を学ぶんだ？

Well, they imitate people who are really good. They'll actually follow them. Like in Kenya, like a good runner will run in the front and then people will run behind him or her and imitate their, the way they run. They'll move their arms and legs, etc. They'll imitate them to try to learn that person's skill, just as we do that for, you know, we watch, you know, Andre Agassi hit a backhand, you know, try to hit the backhand in the same way. And the other thing is that we also use these cushioned running shoes, etc. And we run in different ways. And I think running shoes enable you to slam into the ground so you don't learn to run lightly and gently. And we overstride, we have overly slow cadences. And the other thing is that when people run in other cultures, especially in the Stone Age, you know, they didn't run every day and they weren't running, you know, they didn't stand on one line and run 26.2 miles to another line as fast as they could on a regular basis. And they'd probably go running maybe once a week or something like that, you know. So the idea that you go running five, six times a week, which is what I do, you know, and for long distances on pavement, etc. These are all kind of weird, strange Western things. And there's nothing necessarily wrong with them. And there's nothing necessarily harmful about them. You have to learn how to do it properly. And you have to build up enough strength and learn the skills of running. But let's not scare people off running. I think the most pernicious, the most serious, the most problematic, the most concerning way in which we think about exercise in the Western world is that as people get older, it's kind of normal to be less physically active. And I think that maybe the most important argument that I make in my book is that that's actually really problematic. Because, you know, we evolved, we're a unique species. We evolved to live long after we stopped reproducing. We evolved to be grandparents, basically. And the reason we evolved to be grandparents is that grandparents in foraging societies and also in farming societies are active. They go out and they hunt and they gather or they work in the fields and they help get food for their children and their grandchildren. And that physical activity helps their reproductive success, right? Because they make it more likely for their children and grandchildren to survive and they make it easier for their children to be parents, right? But there's another benefit. And the other benefit is that physical activity is important because it turns on repair and maintenance mechanisms. When you're physically active, you stress your body. You produce what's called reactive oxygen species, which cause cellular damage throughout your body. It causes mutations. It causes inflammation. It causes cells to get kind of cruddy, proteins to get kind of cruddy. But because that's normal, our bodies turn on all kinds of repair and maintenance mechanisms that counter those. We produce antioxidants. Our muscles produce all kinds of molecules that turn down the inflammation of our bodies that causes a wide range of diseases. We repair our muscles. We repair our bones. We repair our brains. We turn on like hundreds, maybe thousands of genes that get turned on by exercise that they're involved in repair and maintenance. And as we get older, that repair and maintenance becomes really important because it prevents senescence. It prevents our bodies from decaying.

まあ、本当にうまい人の真似をするんだ。実際に後をついていくんだ。ケニアのように、上手なランナーが先頭を走ると、みんなその後ろを走って、彼らの走り方を真似するんだ。腕や足を動かしたりね。アンドレ・アガシがバックハンドを打つのを見て、同じようにバックハンドを打とうとするようにね。もうひとつは、クッション性のあるランニングシューズなどを使うことだ。走り方も違う。ランニングシューズを履くと、地面に叩きつけられるから、軽やかに走ることを学べないんだ。そしてオーバーストライドになり、ケイデンスが遅くなりすぎる。もうひ

So when people become physically inactive as they get older, they're no longer turning on those mechanisms that we evolved to use, right, that help us age better and makes us more vulnerable to disease and we age faster. So we evolved to live long in order to be physically active. And that physical activity helps us to live longer and stay healthy because there's an important distinction between healthspan and lifespan, right? We often think about the effects of physical activity on lifespan, how long you live. But really, before the invention of modern medicine, what determined how long you lived was actually how long you were healthy, your healthspan.

つまり、年をとるにつれて運動不足になると、人間が進化してきた、よりよく年をとるためのメカニズムが働かなくなり、病気にかかりやすくなり、老化が早まるというわけだ。つまり、私たちは体を動かすために長生きするように進化したのです。健康寿命と寿命には重要な違いがあるからだ。私たちはよく、身体活動が寿命に及ぼす影響について考えます。しかし実際には、近代医学が発明される以前は、健康でいられる期間、つまり健康寿命が寿命の長さを決めていたのです。

And so healthspan is really the key thing. And what physical activity does is it increases your healthspan and your healthspan therefore increases your lifespan. And until recently, that was what it was all about. And so as we get older, let's not cut back on the physical activity. Let's maintain it. You do some strength, do some endurance. And the evidence is incontrovertible.

つまり、健康寿命が重要なのだ。身体を動かすことで健康寿命が延び、健康寿命が延びることで寿命が延びる。つい最近まで、それがすべてでした。だから、年を取っても身体活動を減らさないようにしよう。維持しましょう。筋力も持久力も。その証拠は議論の余地がない。

There's tons of data which show that as we get older, the more we age, the more physical activity is really beneficial. The most famous study that kind of started all this was actually done at Harvard University. It's called the Harvard Alumni Health Study. And they did it because universities are really good at keeping track of their alums. They constantly ask you for money, right? And so they never lose track of alumni. And so a fellow named Ralph Paffenbarger was at the medical school at Harvard, got the Harvard alumni office to let him find out from alumni what kind of physical activity they were doing. And he asked them health questions and find out how healthy they were and also find out when they died. And what he showed was that younger alums, so one of the advantages of the study is that it kind of controls for socioeconomic status, right? Because these are all Harvard alums back from the old days when they're all basically rich white people, right? So the younger alums who were physically active, they had like 20% lower death rates. So that's good, right? By the time they got to their 70s, the alums who were more active had like 50% lower death rates. And other studies have found the same thing, that physical activity as you get older is more important, not less important for preserving your health. Well, I think there's two issues about the medicalization of exercise. So look, exercise is very medicalized. It's also very commodified, right? And there's nothing wrong with either, right? There's nothing wrong with having fun sports clothes and gyms. And there's nothing wrong with doctors telling people to exercise and all that. But the problem is that it doesn't really work too well. It doesn't get a lot of people motivated. And the proof of that is that 80% of Americans don't get minimum levels of physical activity. And the other problem is that exercise doesn't really fit a medical prescription in a very simple way. There's like no optimal dose, right? People want to know how much to do it and exactly, and there is no answer to that question, right? And then finally, in a way, it's not so much that exercise is medicine, which is what we often say. It's really that the absence of exercise or the absence of physical activity is harmful. And so you're kind of just basically restoring to the body what it kind of essentially needs. And although that sounds like a kind of a trivial distinction, actually, I think it's really profound because it helps us understand on a deep level, you know, the kinds of dosages of physical activity and their effects and how they affect our vulnerability and susceptibility to various kinds of diseases and why it's not really a magic bullet. I mean, people can look at, there are lots of people we can think of, like the last president of the United States, who doesn't exercise, right? And he's in his 70s and looks like he's doing just fine, right? So you don't have to exercise to live a long life. And that makes people kind of, I think, suspicious about the medicalization of exercise. We like to be told what to do. We like to think, you know, you should take X milligrams of this medicine, etc. So you should exercise this many hours a week, right?

年を取れば取るほど、年を取れば取るほど、体を動かすことが本当に有益であることを示すデータは山ほどある。最も有名な研究は、ハーバード大学で行われたものである。ハーバード大学同窓生健康調査と呼ばれています。ハーバード大学は卒業生を把握するのがとても上手なんです。彼らは常にあなたにお金を要求しますよね？だから卒業生を見失うことはない。そこで、ハーバードの医学部にいたラルフ・パフェンバーガーという研究員が、ハーバードの同窓会事務局に頼んで、同窓生からどのような運動をしているかを聞き出した。そして、彼らに健康上の質

We want to know what the optimal dose is. But there is no optimal dose, right? Because first of all, we're all experiments of one, right? You might be young, you might be old, you might be male, you might be female, you might be fit, you might be unfit, you might be living in a suburb, you might be living in a city, you know, you might be previously injured, you might be worried about heart disease, you might be worried about Alzheimer's. There's no one outcome and there's no one nature. It's impossible to prescribe one dose for everybody. So that's one thing.

最適な投与量を知りたい。でも、最適な量なんてないでしょう？なぜなら、まず第一に、私たちは皆、ひとつの実験体だからだ。若い人、年配の人、男性、女性、健康な人、そうでない人、郊外に住んでいる人、都会に住んでいる人、怪我をしたことがある人、心臓病が心配な人、アルツハイマーが心配な人。結果はひとつではないし、性質もひとつではない。すべての人に1つの量を処方することは不可能です。だから、それがひとつなんだ。

And then the other thing is that everything involves trade-offs, right? Exercise is no exception, right? If you exercise more, that's great for some things, but you also could have some negative effects on other things, the most common one being injury, right? You're more likely to hurt yourself, right? So for the vast majority of people, what they're trying to figure out is how to just get enough exercise, right? And I think the important message that often is missed is that if you're physically inactive and you're struggling to be more active, anything is better than nothing. And you don't need to run marathons, you don't need to do a couch to 5k, you don't need to even do necessarily 150 minutes a week, right? Even an hour a week will be better than nothing, right? It can actually lower, on average, somebody's rate of mortality by 30%. If you can get up to 150 minutes a week, on average, it will lower somebody's mortality rate by about 50%. More is better, but eventually it kind of tails off. And so there's no one perfect dose, there's no one perfect type, and I think helping people understand that, I think, relieves them of some of the stress. There's a big debate about whether you can exercise too much, and the answer is that most people think it's true, but we actually don't have a lot of evidence for that. So there was a study that actually just came out from the UK Biobank, huge study of just about everybody in England, right? Large numbers of people in England, along with genetic data, by the way. And of course, there's very, very few people who are doing a huge amount of exercise.

そしてもうひとつは、何事にもトレードオフが伴うということだ。運動も例外ではない。運動量を増やせば、いいこともあるけれど、悪い影響もある。怪我をする可能性が高くなりますよね？だから、大多数の人にとって、どうすれば十分な運動量を確保できるかを考えているんだ。そして、しばしば見落とされがちな重要なメッセージは、もしあなたが運動不足で、もっと活動的になりたいと悩んでいるなら、何もしないよりは何でもした方がいいということだ。マラソンをする必要はないし、カウチ・トゥ・5kmをする必要もない。週に1時間でも、やらないよ

It's a tiny, tiny number of individuals at the end of the curve there, but there's no evidence from that study that the people doing ridiculous amounts of exercise, 30 hours a week or so, had actually any negative effects. And the same is true of some studies that were done in the

しかし、その研究では、週に30時間とか、とんでもない量の運動をしている人たちに、実際に悪影響があったという証拠はない。同じことが

United States. So yes, it's possible, but there's not a lot of evidence. But I'm not really worried about those folks. There's still a few of them. The vast majority of people we're worried about are on the other end of the extreme, who are not getting enough, and let's worry about that.

アメリカだ。だから、可能性はあるけど、証拠はあまりない。でも、その人たちのことはあまり心配していない。まだ数は少ない。私たちが心配しているのは、極端な話、十分な食事がとれていない人たちのほうなのです。

We've medicalized, and this sounds like a strange way of speaking, but we've medicalized disease, right? We've medicalized health, right? For a lot of people, health is the absence of disease.

私たちは医療化してきた。変な言い方だが、私たちは病気を医療化してきた。私たちは健康を医療化してきた。多くの人にとって、健康とは病気がないことだ。

And it is true to a large extent, but health can also be just vigor, vitality, the ability to do what you want. Somebody can have a disability and still be healthy, for example. So what's really important about physical activity and exercise is that it reduces our vulnerability to a wide range of diseases. So you can not exercise and still live a long and healthy life. You can exercise and still get cancer and heart disease and all kinds of other diseases. It's just that physical activity lowers your risk of most of those diseases. And we know that both epidemiologically, we know in terms of the probability that you'll get those diseases if you exercise a certain amount, but we also know how that works based on a wide range of mechanisms. And the most important benefit of exercise is that it decreases inflammation. So inflammation is when your immune system essentially starts to attack you, yourself, right? So if you get a bacterial infection or a viral infection, your immune system kicks into high gear and you attack those invaders. But your immune system can also go on the offensive at such a very low level, that's called chronic inflammation, that you can't really detect it, but it's still there. And it's still kind of attacking things. And it can start attacking your own body. And that leads to heart disease. It leads to diabetes. It leads to Alzheimer's. It leads to osteoarthritis.

しかし、健康とは活力や活力、やりたいことができる能力である場合もある。例えば、障害があっても健康な人はいる。身体活動や運動が本当に重要なのは、さまざまな病気に対する脆弱性を減らすということです。だから、運動しなくても健康で長生きできる。運動をしていても、ガンや心臓病、その他あらゆる病気にかかる可能性があります。ただ、運動することでそれらの病気のリスクが下がるのです。疫学的にも、ある一定量の運動をすればそれらの病気にかかる確率が高いということも分かっているが、様々なメカニズムに基づいてそのメカニズムも分かっ

It leads to a wide range of diseases. And one of the huge benefits of exercise is that it lowers those levels of inflammation. It does so through a number of mechanisms. One is by getting your muscles active, those muscles actually turn down the inflammation with various molecules. The other way is that it reduces the fat around your belly, visceral fat, belly fat, which is very pro-inflammatory. And so the combination of these various consequences of exercise have enormous implications for just lowering people's chances of getting a wide range of chronic diseases that are very debilitating. We spend so much time thinking about how exercise, physical activity is so good for physical health, for diseases that range from heart disease to cancer, et cetera. And that's all true. Not in any way want to minimize that. But I think we often undervalue just how important physical activity is for mental health.

炎症はさまざまな病気を引き起こす。運動の大きなメリットのひとつは、炎症レベルを下げることだ。それにはいくつかのメカニズムがある。ひとつは、筋肉を活性化させることで、筋肉がさまざまな分子で炎症を抑えることです。もうひとつは、お腹の周りの脂肪、内臓脂肪、お腹の脂肪を減らすことです。運動がもたらすこのようなさまざまな結果の組み合わせは、人々を非常に衰弱させるさまざまな慢性疾患にかかる可能性を低下させるだけでなく、非常に大きな意味を持つのです。私たちは、運動や身体活動がいかに身体の健康にいいか、心臓病からガンまで

When you're physically active, your brain turns on a whole cocktail of chemicals that are really good for you. It turns on dopamine and serotonin, which are important for anxiety and depression and mood. You produce opioids, which of course can make you happy. And even in extreme cases, endocannabinoids, which can make you high and make you feel really good.

体を動かすと、脳は体に良い化学物質のカクテルのスイッチを入れる。ドーパミンやセロトニンが分泌され、不安やうつ、気分に重要な働きをする。オピオイドも生成される。極端な例では、エンドカンナビノイドも生成される。

And study after study after study shows that physical activity has important immediate benefits on people's mental health. And so one of the crises I think of the pandemic has been as people's physical activity levels down, I think it's partly responsible for some of the stress and the anxiety and the depression that's on the rise recently today. And one way to help, simple way to help folks. I mean, it's not a magic bullet. It's not going to cure it overnight. But it's certainly a potent part of our tool to help people is to help people be more physically active. It has enormous effects on people's mood and mental health. We think so much about exercise in terms of elite athletics. The fastest, the highest jumping, the strongest, et cetera. Because you turn on the TV and that's where we see amazing athletes do amazing things. And it's wonderful. It's great entertainment. But that's actually kind of what it is. It's actually entertainment. I mean, what the world's fastest runners are able to do or the world's best basketball players are able to do have almost nothing to do with what most of us do. I mean, I can run. I'm a pretty good runner.

そして、研究に次ぐ研究で、身体活動は人々の精神的健康に重要な即効性があることが示されている。パンデミック（世界的大流行）の危機のひとつは、人々の身体活動レベルが低下していることで、最近増加しているストレスや不安、うつ病の一因になっていると思います。そして、人々を助ける簡単な方法がある。つまり、魔法の弾丸ではありません。一晩で治るわけではない。しかし、人々を助けるためのツールの一部として、人々がもっと体を動かすように手助けすることが有効であることは確かです。運動は人々の気分や精神的健康に多大な影響を与える。

And I struggle to run like a six minute mile. And the world's best marathoners are running 440 miles for 26 miles. I mean, I can't even dream of that. I can't run one mile that fast. I can't even run a half a mile that fast. And so we get this kind of, I think, sometimes a perverted idea about what's normal from elite athletics. Because we're looking at the extremes, the best of the best of the best of the best of the best. And while that's amazing and impressive, these are people who've spent years of their lives training to do just one thing and one thing really well.

そして私は1マイルを6分台で走るのに苦労している。世界最高のマラソン選手は26マイルを440マイルで走っている。つまり、私には夢にも思えない。1マイルをそんなに速く走れない。半マイルもそんなに速く走れない。だから私たちは、エリート陸上競技から、何が普通なのかという曲解した考えを得ることがある。なぜなら、私たちは極端なものを見ているからだ。それは素晴らしいことであり、印象的なことではあるが、彼らはただひとつのことを、ひとつのことを本当にうまくこなすために、何年もかけてトレーニングしてきた人たちなのだ。

That's not what most of us do. And they've gotten lucky in the genetic lottery. They've got a lot of genes, which I don't have, which give them certain kinds of capabilities. And I do worry that sometimes our focus on elite athletics can actually be off-putting rather than inspiring.

私たちのほとんどはそうではない。彼らは遺伝子の抽選で運が良かったんだ。私にはない遺伝子をたくさん持っていて、それが彼らにある種の能力を与えている。エリートアスリートへの注目は、時に感動を与えるどころか、かえって不快感を与えることもあるのではないかと心配している。

I think that one of the things that people really struggle with when I talk to them about the research that I do is that they struggle to understand both the nature of research in general, but also evolutionary research in particular. Because research is a process. You never know the truth. And so when I pick up a paper written by somebody else or my own work, or when I do an experiment, I'm not trying to think, oh, can I prove this? What I'm trying to actually do is say, can I disprove this? And I'm trying to be really critical about it.

私が行っている研究について話すとき、人々が本当に悩むことのひとつは、一般的な研究と、特に進化学的研究の両方の性質を理解するのに苦労することだと思う。研究とはプロセスだからだ。真実は決してわからない。だから、誰かが書いた論文や自分の研究を手に取るとき、あるいは実験をするとき、私は、ああ、これを証明できるだろうか、と考えようとはしない。私が実際にやろうとしているのは、これを反証できるかということだ。そして、私はそれについて本当に批判的であろうとしている。

So when we think about, for example, the effects of physical activity and exercise on the body,

だから、たとえば身体活動や運動が身体に及ぼす影響について考えるとき、