【中级听力】（文末附视频）What’s Inside a Camel Hump?

What’s Inside a Camel Hump?

《文 末 附 视 频》

This may not be a word-for-word transcript.

Narrator: Did you know that camels used to live in the Arctic tundra? Yes, camels, walking around on ice and snow. It’s true. In 2013, scientists announced they’d discovered mummified leg bones on Ellesmere Island, which belonged to the ancestors of modern-day one-and two-humped camels. In fact, enduring the frigid tundra is how scientists think camels got their iconic hump in the first place, because what’s inside helped them survive in an age when many other animals were wiped out.

John Hare: What’s inside a camel’s hump is fat, and a lot of people think it’s water. But it’s certainly not; it’s fat, and it nourishes them when they’re on long journeys.

Narrator: That’s right, fat. Each hump can store up to 36 kilograms of it, which can sustain the camel for weeks or even months without food. And that sort of adaptation was especially important 3.5 million years ago, during the middle of an ice age, when the ancestors to modern camels were hanging out in the Arctic tundra.

John Hare: Talking about the Ice Age, when a lot of mammals were killed during that time, and yet the camel managed to survive by developing this emergency food system, if you like: the hump.

Narrator: Eventually, camels migrated across the Bering Strait into regions of Asia and Africa, where the fat inside their humps helped them adapt yet again – this time – to the blistering-hot temperatures of deserts like the Gobi and Sahara. You see, camels are one of the only animals in the world that store all their fat in one spot. And that’s useful for keeping cool in a hot climate because heat can escape faster from the rest of their body, which helps them maintain a lower body temperature. Compare that to other mammals, like humans, who store fat all over, making it a lot harder to stay cool.

Today, camels still use the fat in their humps as a food reserve, but they’re not the only ones. In extreme circumstances, the Turkana tribe in Kenya, for example, will eat camel fat to survive.

John Hare: They suffer a lot from periods of extreme drought, and I have seen these people, they’ve been very, very short of food, and this is difficult to believe, but it’s true, slit open the top of a camel’s hump, take out the fat for their own consumption, and then put the top of the hump back on again.

Narrator: But don’t worry, the camel makes a full recovery, and instances are rare. But this practice has started to generate some buzz around camel fat as a new superfood. Turns out, camel fat is loaded with fatty acids, vitamins, and minerals. Desert Farms, a company that sells camel fat, says that just 1 tablespoon contains 40% of your daily vitamin B12 needs and three times the amount of oleic acid than coconut oil, a superfood staple. And since all that nutritious fat is what fills the hump out, when a camel fasts for long periods, its hump can actually go limp.

John Hare: The humps gradually diminish in size. If it’s been in a very harsh environment, they go completely limp and flop over the side of the camel’s backbone.

Narrator: Now, since we know that fat is what makes up the hump instead of water, that got us wondering: How do camels stay hydrated in such dry climates? Well, they have unique blood cells that run throughout their entire body, including a few in the hump itself. These blood cells are extremely elastic, perfect for holding a lot of water. Camels can drink up to 115 liters in about 10 minutes, expanding the cells up to 240% in the process.

John Hare: There are capillaries throughout its body, and when it has a drink, it drinks and drinks and drinks, and it swells up, and it looks as though it’s pregnant. 

Narrator: If that’s not impressive enough, the wild camel of China has even been known to survive on saltwater. So, whether it’s surviving the harsh desert heat, weeks without food and water, or even the Canadian Arctic, the camel is one of the best adapters in the animal kingdom, and that’s in large part thanks to its iconic hump.

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