Longer Limbs

Animals that live in cold climates tend to have stubby limbs—shorter arms and legs—even smaller ears and tails. Picture a penguin and you’ll see what I mean. Biologists have long assumed that these stumpy appendages are an evolutionary adaptation. Shorter extremities minimize heat loss, so animals that are more compact are better suited to the cold.

But scientists from Ohio say that temperature may have a more direct effect on the length of an animal’s limbs. Because they find that turning up the heat helps cartilage grow—results that were published in the Proceedings of the National Academy of Sciences.

The researchers raised mice at several different temperatures, and they confirmed that those kept at a balmy 80 degrees were longer limbed than those who lived at a more chill 45. But how does a little heat make mice more leggy? The answer, they find, lies in the cartilage. Long bones grow from the cartilage found at either end. And the warmer it is, the more that cartilage grows, even when it’s just sitting in a test tube. Which I guess means it’s possible that the dog days of summer lead to longer-legged dogs.

更长的四肢

生活在寒冷地方的动物其四肢倾向于长得短而粗——就是耳朵和尾巴也要小一些。想想企鹅你就明白我的意思了。生物学家们长久以来认为这些短而粗的附肢是一种进化过程中的适应。更加短小的四肢能使热损失降到最低，所以，体型粗短的动物能更好地适应寒冷气候。

不过来自俄亥俄 (Ohio)的科学家们报道说，温度可能对动物四肢的长度有更直接的影响。因为，他们发现提高温度能帮助软骨组织的生长——这些研究结果发表在《美国国家科学院院刊》(Proceedings of the National Academy of Sciences)上。

研究者们在不同的温度下饲养老鼠，他们证实与生长在寒冷的45度 （译者注：这里指华氏度，45华氏度相当于7.2摄氏度）下的老鼠相比，那些生长在温和的80度 （80华氏度相当于26.7 摄氏度 ）下的老鼠的四肢要长一些。但是温度的提高是怎样使老鼠的腿长得更细长的呢？研究者们发现答案在于软骨组织。长的骨骼是从骨头两端的软骨组织生长而来。气温越暖和，软骨组织长得越长，即使在试管中也是如此。根据这个研究，我猜想这可能意味着炎热的夏天会使狗的腿长的更长。

Vocabulary:

Limb: 四肢
Stubby: 短而粗的
Penguin: 企鹅
Assume: 假设；
Stumpy: 树墩似的；短而粗的
Appendage: 附属物
Evolutionary: 进化的
Extremities: (医学)四肢，手足
Minimize: 最小化
Compact: 紧密的；简洁的
Cartilage: 软骨组织
Confirm: 确认
Balmy: （气候）温和的
Chill: 寒冷的
Leggy: 腿细长的；露腿的
The dog days of summer： 夏季最闷热的时候