◆双语阅读
What makes humans different from other animals? Ask any ten people and you’re likely to get ten different answers, ranging from our relatively large brains, to our incredible use of language and symbols, to our ability to dramatically modify the world around us. But if you asked me, I’d say that it’s our butts.Take a look around the animal kingdom. Even our closest living relatives among the great apes (chimpanzees, bonobos, and gorillas), don’t have proportionally as big butts as humans do. The main reason for this probably comes down to our unique style of locomotion. We’re the only mammals alive today whose primary way of getting around is walking on two legs. And becoming upright bipeds has had some important consequences for our derrières.
人类与其他动物的不同之处是什么？你问十个人可能会得到十个不同的答案，答案可能包括我们相对较大的大脑、我们惊人的语言和符号使用水平，到我们极大地改变周围世界的能力等等。但如果你问我，我会说答案是我们的臀部。看看动物王国。即使是我们现存最近的亲戚——大猩猩、倭黑猩猩和黑猩猩——它们的臀部也没有人类那么大。造成这种差异的主要原因可能与我们独特的运动方式有关。我们是现存唯一主要通过双足行走的哺乳动物。而成为直立的双足动物，给我们的臀部带来了重要的影响。
The anatomical structure that we generally think of as a “butt” is made up of adipose tissue (fat) sitting on top of our gluteal muscles, which are attached to the bony pelvis. Ultimately, it’s the shape of our pelvis that dictates the shape of our butts, and that set of bones has undergone some major changes over the last six-or-so million years.
从解剖结构上看，我们通常所认为的“屁股”是由附着在臀大肌上的脂肪组织（脂肪）构成，而臀大肌则附着在骨盆上。归根结底，正是我们的骨盆形状决定了我们屁股的形状，而人类骨架在过去大约六百万年的时间里经历了一些重大变化。
The pelvis is made up of three parts: two innominates (or “hip bones”) and the sacrum. Each innominate is also made up of three bones (the ilium, ischium, and pubis) that fuse together during growth and development. And it’s the ilium that’s the real difference-maker between us and our ape relatives. A chimpanzee’s ilium is relatively tall and flat, with the flat sides facing forwards and backwards. Our ilia, on the other hand, are short and curved around more to the sides, making our pelvis bowl-shaped. These size and shape differences are linked to the evolution of bipedalism and the reorganization of our gluteal muscles that make upright walking possible.
骨盆由三部分组成：两块髋骨（或称“髋骨”）和骶骨。每块髋骨还由三块骨头（髂骨、坐骨和耻骨）构成，这些骨头在生长发育过程中会融合在一起。而正是髂骨的形状，把我们与类人猿亲戚真正区别开。黑猩猩的髂骨相对较高且扁平，扁平的髂骨一侧朝前一侧朝后。而我们的人类髂骨则短而弯曲，更多地向两侧延展，使得我们的骨盆呈碗形。这些大小和形状的差异与双足行走的进化以及臀部肌肉的重组密切相关，从而使得直立行走成为可能。
The three gluteal muscles are gluteus maximus, gluteus medius, and gluteus minimus (“gluteus” derives from the Latin for “butt”, so that’s “biggest butt,” “medium butt,” and “smallest butt”). Our gluteus maximus (especially the upper part) is very large compared to that of other primates. It extends the thigh and moves it backwards, and gives us power when we run or climb stairs. And it’s what gives our behind most of its shape. In other apes, though, the so-called “lesser gluteals” (gluteus medius and minimus) do a lot of this work, so the gluteus maximus doesn’t have to be a major player. Hence, no booty. What our lesser gluteals are doing instead is helping our hips not drop to the side when we stand on one leg (as we do every time we take a step forward). It’s the curved shape of our ilia that allows them to do that, by changing where those muscles are and, thus, their function. Our lesser gluteals provide stability rather than power.
三块臀肌分别是臀大肌、臀中肌和臀小肌（“gluteus”来自拉丁语，意为“臀部”，因此它们分别意为“最大的臀部”、“中等的臀部”和“最小的臀部”）。与其他灵长类动物相比，我们的臀大肌（特别是臀大肌上部）非常大。它负责伸展大腿并使其向后移动，在我们奔跑或爬楼梯时提供力量。它也是塑造我们臀部外形的主要肌肉。然而，在其他猿类中，所谓的“次要臀肌”（臀中肌和臀小肌）承担了许多这个功能，因此臀大肌并不需要发挥重要作用。所以，它们没有“屁股”的形状。我们的次要臀肌的作用则是帮助我们在单腿站立时防止臀部下沉（我们每次迈步时它都会发挥这类作用）。正是我们髂骨弯曲的形状使它们能够通过改变这些肌肉的位置，进而改变它们的功能，从而完成这一任务。我们的次要臀肌提供的是稳定性而不是力量。
The last thing that helps make human butts unique is the fat — which might also have something to do with us becoming bipeds. Humans have relatively large brains that use a lot of energy. Our bodies store energy as fat, and we have a relatively high percentage of it for a non-aquatic mammal. This has led anthropologists to suggest that our body fat helps buffer our metabolically-expensive brains against lean times. This seems to be something that we are able to do because walking on the ground is both an energetically efficient way to get around. It also avoids the downsides of spending our lives in trees — having to support all of our weight on tree branches and exist at the mercy of gravity requires a lot of energy.
让人类的屁股如此独特的最后一个原因在于脂肪——这可能也与我们成为双足行走的动物有关。人类的大脑相对较大，消耗大量能量。我们的身体将能量以脂肪的形式储存起来，并且对于非水生哺乳动物来说，我们的脂肪比例相对较高。这导致人类学家提出，人体脂肪有助于给我们代谢需求高的大脑在食物匮乏时的能量供应提供缓冲。这似乎是我们能够做到的一件事，因为在地面上行走不仅是一种节能高效的移动方式，同时也避免了生活在树上的各种弊端——需要依靠树枝承载全部体重，并且完全受制于重力，这会消耗大量的能量。
本文节选自：massivesci.com
发布时间：2020.8.31
作者：Darcy Shapiro
原文标题：How did human butts evolve to look that way?
◆词汇积累
1. butt
/bʌt/
n. 烟蒂，烟头; (武器或工具)粗端; 笑柄; 屁股; (头的)顶撞; 大桶; 枪靶，靶场; (尤指接近地面部分的)树干
v. 用头(或角)顶，撞; (使)毗连，相邻
2. locomotion
/ˌləʊkəˈməʊʃən/
n. 运动；移动；旅行
3. biped
/ˈbaɪpɛd/
adj. 有两足的
n. 两足动物
4. anatomical
/ˌænəˈtɒmɪkəl/
adj. 解剖的；解剖学的；结构上的
5. adipose
/ˈædɪˌpəʊs/
adj. 用于贮存脂肪的；脂肪的
n. 动物脂肪
6. gluteal
/'gluːtɪəl/
n. 臀肌
adj. 臀肌的，和臀肌有关的
7. pelvis
/ˈpɛlvɪs/
n. 骨盆
8. sacrum
/ˈseɪkrəm/
n. 骶骨；荐骨
9. primate
/ˈpraɪmeɪt/
n. 灵长目动物(包括人、猴子等)；大主教；首领
adj. 灵长目动物的；大主教的
10. booty
/ˈbuːtɪ/
n. 战利品；赃物；获得之物；屁股，臀部
11. buffer
/ˈbʌfə/
n. 起缓冲作用的人(物); 缓冲存储器，缓存; (铁路机车头尾的)缓冲器，减震器; (用于擦亮表面的)抛光工具
v. 保护(某物); 缓解，缓冲; 存储，缓存(数据等)
◆词组搭配
1. at the mercy of 受制于；处于…支配下
◆写作句总结
原句：The anatomical structure that we generally think of as a “butt” is made up of adipose tissue (fat) sitting on top of our gluteal muscles, which are attached to the bony pelvis.
结构：The sth that we generally think of as X is made up of Y sitting on top of Z, which are attached to A.
例句：The challenges that we generally think of as obstacles are made up of experiences sitting on top of our mindset, which are attached to our personal growth.