SSS 2008-12-08

（单词翻译）

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

Animals that live in cold climates tend to have stubby limbs—shorter arms and legs—even smaller ears and tails. Picture a penguin¹ and you’ll see what I mean. Biologists have long assumed that these stumpy appendages² are an evolutionary³ adaptation. Shorter extremities⁴ 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 Proceedings⁵ 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.

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.