人類為什么能成為地球上最厲害的長(zhǎng)跑健將？
Each year, a small town in Wales holds the Man Versus Horse Marathon. It's a 22-mile race between riders on horseback and runners. And, while horses often win, humans will sometimes prevail.
威爾士的一個(gè)小鎮(zhèn)每年都會(huì)舉辦“人馬長(zhǎng)跑大賽”，由騎馬者和跑步者共同參與，賽程約為35公里。雖然騎馬者常常勝出，但人類有時(shí)也能獲勝。
So what makes humans such endurance running superstars?
那么，人類為什么能成為長(zhǎng)跑健將呢?
The secret weapon is our sweat. We have 2-4 million sweat glands all over our body, which means we can run and cool ourselves at the same time. Having no fur is also a huge plus.
我們的秘密武器是汗液。人類全身覆蓋著200萬至400萬個(gè)汗腺——也就是說，我們能夠一邊跑步一邊降溫。另外，沒有皮毛也是一大優(yōu)勢(shì)。
In contrast, dogs rely on panting to cool down, and other animals, like horses and camels, also sweat, but less effectively. As a result, they overheat faster and must slow down sooner.
相較而言，狗要靠喘氣降溫;馬、駱駝等其他動(dòng)物雖然也流汗，但降溫效果不如人類。因此，它們的體溫會(huì)更快過熱，需要盡早減速。
The mechanics of our running stride also makes us particularly well-suited for endurance running. A human's running gait has two main phases: Aerial when both feet are off the ground and Stance when at least one foot touches the ground.
另外，人類的跑步步法也使我們格外適合長(zhǎng)跑。人類跑步的步態(tài)有兩步——騰空：雙腳均離地;站立：至少一只腳著地。
While in the air, gravity pulls us down, which generates a lot of kinetic energy. However, the second we hit the ground, we instantly decelerate, losing that kinetic energy in the process.
騰空時(shí)，重力會(huì)把我們往下拉，這個(gè)過程產(chǎn)生了大量動(dòng)能。不過，著地時(shí)會(huì)立刻減速，失去這種動(dòng)能。
Here's where our special adaptations come in. The tendons and muscles in our legs are very springy. They act like a pogo stick, converting kinetic energy from the aerial phase into elastic potential energy, which we can use later.
而人類獨(dú)特的適應(yīng)性就體現(xiàn)在這里。我們的大腿肌腱和肌肉極具彈力，它們可以像彈跳器一樣將動(dòng)能轉(zhuǎn)化為彈性勢(shì)能，以供之后利用。
In fact, our IT band can store 15-20 times more elastic energy than a chimpanzee's similar body part, the fascia lata. When it comes time to step off, those springy tendons can turn 50% of that elastic pogo-stick energy back into kinetic, making it easier to propel forward. Without that extra energy, we'd have to exert that much more effort just to take a step.
事實(shí)上，人類的髂脛束(包繞大腿的深筋膜)能夠儲(chǔ)存的彈性勢(shì)能是黑猩猩的相似部位闊筋膜的15-20倍。當(dāng)我們邁步時(shí)，富有彈性的筋腱可以將50%的彈性勢(shì)能轉(zhuǎn)化為動(dòng)能，使我們更容易前進(jìn)。如果沒有這種額外能量，那么我們需要付出更多努力，才能夠前進(jìn)一步。
So, why did humans get to be such great endurance runners, anyway?
那么，人類為何能成為如此卓越的長(zhǎng)跑健將呢?
Some anthropologists believe this became important around 2-3 million years ago, when we started hunting and scavenging. Because we couldn't chase down a gazelle like a cheetah, early humans learned persistence hunting. Where they would track prey over long distances until the prey either overheated or was driven into a trap.
一些人類學(xué)家認(rèn)為，大約在兩三百萬年前，當(dāng)人類開始狩獵和覓食時(shí)，長(zhǎng)跑能力變得至關(guān)重要。因?yàn)槿祟悷o法像獵豹一樣追捕瞪羚羊，于是我們學(xué)會(huì)了耐力狩獵。他們會(huì)追蹤獵物很長(zhǎng)一段距離，直到它們體溫過熱或被逼進(jìn)陷阱。
In fact, persistence hunting remained in use until 2014, such as with the San people of the Kalahari Desert.
事實(shí)上，到了21世紀(jì)，依然有人類在使用這種狩獵方法，例如，喀拉哈里沙漠的非洲原住民桑人。
But distance running can still help you, even if you're not interested in running down your next meal.
即便你現(xiàn)在對(duì)追獵覓食沒興趣，但長(zhǎng)跑依然有益身體。
Studies show running can lower body weight, body fat, and cholesterol levels. And the longer you train, the greater the health benefits. Just one year of training has been shown to reduce body weight by about 7 lbs, lower body fat by 2.7% and decrease resting heart rate by 2.7%.
研究顯示，跑步能夠降低體重、體脂和膽固醇水平。跑步時(shí)間越久，健康益處越明顯。一年的長(zhǎng)跑訓(xùn)練能夠使體重降低約3公斤，體脂降低2.7%，靜息心率降低2.7%。
