It's Oscar Pistorius, who you might also know for murdering his girlfriend, but this is a video about feet, so let's set that aside.

他是 Oscar Pistorius，你可能因為他謀殺了自己女朋友而知道這個人，不過今天影片的主題是腳，所以我們先把這個問題放到一邊去吧。

Pistorius had to fight for his right to compete in the Olympics by proving to officials that his blade like prosthetic feet didn't give him an extra advantage over athletes running on regular old flesh feet.

Pistorius 為了在奧運比賽中出場，必須竭盡全力向奧委會官員們證明，他那如同刀刃般的仿生足部並不會讓他與其他以血肉之軀奔跑的對手們比賽時，帶給他額外的優勢。

There are other blade runners fighting the same fight behind him.

其他刀鋒跑者們也在他身後同樣奮鬥著。

The German long jumper, Markus Rehm was barred from competing in the Rio Olympics.

德國跳遠選手 Markus Rehm 在里約奧運時被禁止參賽。

The college track athlete Hunter Woodhall had to make the case to the NCAA.

大學田徑運動員 Hunter Woodhall 則必須說服 NCAA (美國國家大學體育協會) 才能上場比賽。

And Paralympian Blake Leeper is gearing up for the same fight to compete in the 2020 Olympics.

殘奧會運動員 Blake Leeper 正在為參加 2020 年奧運會做同樣的準備。

And it all makes you wonder why does the foot designed in a lab looks so different from the biological human foot?

而這一切不禁讓人納悶：為什麼在實驗室裡設計出來的足部，和人類天生的足部看起來那麼不一樣？

It might be because the human foot is kind of a design disaster.

這可能是因為人類的足部就是一場設計災難。

Podiatry is a $5 billion industry.

足科是一個有著 50 億美元產值的產業。

A majority of Americans will experience significant foot pain at some point in their lives,

大部分的美國人在一生當中生命幾乎都會經歷過明顯的足部疼痛，

and as many as 10% of us will experience inflammation in the band of tissue along our arches, otherwise known as plantar fasciitis.

而多達 10% 的人沿足弓的組織帶將會有發炎狀況，這也就是所謂的足底筋膜炎。

Why though? Weren't humans evolved to walk long distances and isn't walking upright on two legs the trait that for separated us from other primates?

然而為什麼會這樣？人類不是已經演化出可以走長遠路途的身體了嗎？而兩足直立行走不正是我們與其他靈長類最大的區別嗎？

So why hasn't natural selection, selected a cooler, better, less injury prone foot for us?

既然如此，為什麼天擇並沒有幫我們選出一個更酷、更棒、更不會受傷的足部呢？

Some theories posit that we're so plagued by foot problems because we evolved to walk barefoot out in nature over soft, sweet earth,

一些理論認為，我們之所以深受腳部問題的困擾，是因為我們的腳是演化成用來走在自然的柔軟土壤上的，

but now we've thrown off the delicate biomechanical balance of our feet by wearing big mushy, cushiony tennis shoes.

但由於我們穿上了又大又重的氣墊鞋，讓我們足部那精巧的生物醫學平衡被捨棄了。

Meanwhile, our bones take a beating from walking and standing on super hard surfaces like concrete.

於此同時，我們的骨頭則因為行走和站立在像是水泥等極為堅硬的表面上而受傷。

But other researchers say it goes back way further than that.

但其他研究員則指出原因其實更為深遠。

Jeremy DeSilva is an anthropologist who studies human evolution and argues that foot problems exist way back in the fossil record.

Jeremy DeSilva 是個研究人類演化的人類學家，而他認為人類的足部問題其實能從化石紀錄中看出端倪。

Fossils show evidence of osteoarthritis and compression fractures and flat arches, which means foot pain millions of years ago.

化石呈現了關節炎、壓迫性骨折、扁平足等症狀的證據，代表數百萬年前人們就已經飽受足痛之苦了。

DeSilva makes a convincing case that the real source of our foot problems is the janky design.

DeSilva 提出了令人信服的證據，說明了我們的足部問題其實是演化途中東拼西湊的結果。

As I mentioned earlier, what we're looking at are our paper clips and duct tape.

正如前面提到過的，我們眼前的足部簡直是用迴紋針和膠帶修修補補下的結果。

Our primate ancestors spent most of their time in trees.

我們的靈長類祖先大多時候都在樹上活動。

Our feet then were originally meant for climbing and grasping, but 4 million years ago, and possibly earlier, some apes started dabbling in bipedalism.

於是我們的腳掌本來是用來爬樹和抓握的，但在四百萬年或更早以前，一些猿猴決定開始兩足步行。

Experts haven't agreed on why hominids developed this trait.

專家們還沒有對為何人類發展出這種特性的原因達成共識。

Perhaps it was a more efficient way to travel while scavenging for food,

也許這是種在採集食物時能夠更有效長途旅行的方式，

Or maybe it was to enable persistence hunting, tracking prey over such long distances that they became overheated and simply laid down from exhaustion, no weapons required.

又或者是人類能藉此進行耐力消耗狩獵，追蹤獵物相當長的距離直到牠們體力不支，因為疲勞而發燒導地為止，不費一刀便能完成狩獵。

Whatever the reason, bipedalism is the defining trait of humans.

不論原因為何，兩足步行是人類最具象徵性的特色。

Going bipedal involved some painful anatomical tradeoffs, including everything from where the spine attaches to the skull, to the angle of the femurs, and of course, the shape of our feet.

轉變為兩足步行牽涉到一些在生理構造上痛苦的代價，範圍從我們脊椎與頭骨的連接位置到大腿骨的角度，還有理所當然的，我們足部的形狀。

Let's talk mechanics.

讓我們來從機械學角度說起吧。

A foot is a propulsive lever.

足部是一個推進的槓桿。

It needs to be stiff enough that we can push off the ground and propel ourselves forward,

它需要有足夠的硬度以便我們能夠推離地面，推動自己前進。

but it needs to be elastic enough to store the mechanical energy that's generated each time the foot strikes the ground.

但它也要有足夠的彈性來儲存每次足部著地時所產生的機械能。

That's how designers ended up with this blade shape for athletes.

這就是設計師們最後將為運動員們設計的義足打造成這種刀片形狀的原因。

The human foot, on the other hand, has 26 bones, 33 joints and over 100 muscles, tendons and ligaments.

相對來看，人的足部有 26 塊骨頭，33 個關節和超過 100 條肌肉、肌腱和韌帶。

That's because it was built for grasping. All those joints let it flex. So it's not inherently rigid enough to give us the propulsive power we need.

這是因為它是為抓取所打造出來的。這些關節讓它能夠彎曲。因此它本來就不具備能給予我們走路時所需推進力的結實程度。

Here's what had to change.

於是我們的足部經歷了下面的改造。

Back when we were climbers, our big toe used to be opposable like our thumbs, but to help make the foot more rigid, it became shorter, stiffer and in line with our other toes.

當我們還攀爬在樹上生活時，我們的腳拇指就像手的拇指一樣可以碰觸到其他四根指頭，但為了讓足部具有更高強度，腳拇指於是變得更短、更結實且與其他指頭平行並排。

And we developed arches to absorb the force of impact each time our foot hits the ground.

我們發展出了足弓來吸收每次踏上地面時所接收到的衝擊。

Our ligaments got thicker to help hold all these small bones firmly in place.

我們的韌帶變得更加厚實，將這些小小的骨頭們確實地固定在一起。

Bipedal Locomotion is a notoriously complex mechanical engineering puzzle that scientists have been working on for decades.

兩足步行是個科學家們數十年一直在嘗試解決，複雜得臭名昭彰的機械工程難題。

And in the case of human feet, you could say natural selection is still in the early design phase.

而至於人類足部的構造嘛，我們可以說它仍處於早期設計階段。

DeSilva uses the ostrich as an example of a foot from the natural world that resembles the prosthetic blades that were perfectly designed for running on two feet.

DeSilva 將鴕鳥做為自然世界中，專門用來以雙足高速奔跑的完美範例，與義肢足刃的外型相仿。

But he also points out birds have a big bipedalism head start.

但他也指出，鳥類在雙足步行的演化上有著巨大先天優勢。

Just look at their ancestors.

看看牠們的祖先就知道了。

They've been bipedal for 230 million years, while we've only been bipedal for about five million.

牠們已經以雙足步行過上了 2.3 億年，而我們才發展出雙足步行的特徵大約 500 萬年而已。

And a big takeaway from his talk?

從他的談話中拿到的最大的收穫？

Natural selection isn't selecting from an endless menu of options.

自然選擇並不是從一個無盡的菜單中選擇的。

Rather, it's a constant series of small modifications to the original design.

相對的，它是對原始設計所不斷進行的一系列細微修改。

So in our case, it's slowly modified, flexible graspy hands into more rigid propulsive levers, which left us kind of vulnerable to some aches and pains.

因此在人類足部的演化中，我們的足部被慢慢地被修改，靈活的抓握手變成了更結實的推進部位，於是讓我們容易遭受一些疼痛。

But considering our feet are modified ape pains, they do a pretty good job.

不過考量到我們的足部基本上就是略為改裝過的猿猴腳掌，其實它們已經算是不錯了啦。

And considering we're the most successful primate, nay mammal nay species(?) on the planet, it's a pretty decent compromise.

再考量到我們不但是地球上發展最成功的靈長類，更是最成功的哺乳類甚至是物種，這算是個不錯的妥協。

Thanks for watching.

謝謝你的觀看。

If you're super interested in the scars of human evolution, you can see the whole talk on Boston University's YouTube page.

如果你對人類進化過程中的傷痕非常感興趣，你可以到波士頓大學的 YouTube 上觀看整個演講。

If you liked this video, hit the bell icon so that you can get notified each time Cheddar posts a new video.

如果你喜歡這部影片，記得點擊小鈴鐺，這樣每次 Cheddar 發布新影片是你便能獲得通知。

Thanks again! We will see you next time.

再次感謝！我們下次再見。