科学家给乌鸦投喂了 125 个汉堡之后…… | 科学60秒

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▶ 科学60秒：为了完成这项研究，她给乌鸦投喂了 125 个汉堡 | 2:52

我们的饮高脂食

让身边的动物也成了受害者

图片来源：Andrea Townsend

高胆固醇影响着美国三分之一的成年人，但是受害者不只有我们！研究表明，其他动物体内的胆固醇也有了明显升高。

“所有这些研究的主要观点就是，这一现象的原因可能是动物与人类的互动接触，以及动物对人类食物的摄入。但是实际上这些研究却没有证明这点。”安德里亚·汤森德（Andrea Townsend）说道，她是纽约州北部汉密尔顿学院（Hamilton College）的一名鸟类生态学家。她发现，城市乌鸦确实比农村乌鸦拥有更高的胆固醇水平。

 

在自己的研究中，她采取了更进一步的逻辑性探索：去麦当劳。“我们一下子买了 125 只汉堡。一旦有人问我们需要这么多汉堡干什么，我就开始解释，不过还没等我说完，他们就挥手让我们走了。”

显而易见，她要用这些芝士汉堡去喂食乌鸦，然后监控它们的饮食，来确定吃人类的快餐食物是否真会提高鸟类胆固醇水平。

“所以我们给‘幼鸟补充营养’的方式是：找到筑有鸟巢的树，每三到五天将汉堡扔到树下。鸟爸鸟妈们会立刻扑下来，叼起汉堡，带回巢里给自己的孩子吃。”

你或许可以预见到，经常吃汉堡的乌鸦确实要比不吃汉堡的同类胆固醇水平更高。但这里还有令人意外的发现：在开始吃汉堡之后的头三年内，更高的的胆固醇并没有影响乌鸦的生存率。在某一乌鸦群体中，胆固醇水平更高的乌鸦可以说比其他乌鸦状态更好了，也就是更丰满了。

研究结果发表在鸟类杂志《秃鹰》（Condor）上。

乌鸦的寿命可长达 15 年以上，汤森德表示，高胆固醇饮食的危害可能会在乌鸦晚年显现出来，就跟人类一样。但如果你仍执意想问：“为什么要研究这个？”

“我想说这是一个相当重要的问题，因为城市里还生活着许多其他物种，它们也会吃我们的食物，而其中有些正濒临灭绝……[查看全文]

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Cholesterol Climbs after Crows Chomp Cheeseburgers

High cholesterol affects a third of American adults. But it’s not just us! Studies have indicated that cholesterol is also on the rise in other animals. 

“And in all of these studies, the idea was it was probably due to interactions with people and eating our food. But they didn’t actually show that.”

Andrea Townsend is an avian ecologist at Hamilton College in upstate New York. And she found that urban crows did have higher cholesterol than rural crows. 

But then she took the next logical step in her research. She went to McDonald’s. “We’d pick up 125 burgers at a time. Once one of them wanted to know what we needed all these burgers for, and I started to explain, but they just kind of waved me away halfway through.”

Of course, she needed all those cheeseburgers to feed crows and to monitor their diet—to determine if eating our fast food really does raise the birds’ cholesterol.

“So the way you ‘supplement your nestlings’ is: we’d go to their nest trees, we’d toss the cheeseburgers, three to five a day, under their nest trees. The parents would immediately swoop down, pick up the burgers and bring them to their nestlings.”

And as you might expect, crows that dined on cheeseburgers did indeed have higher cholesterol than crows who did without. But here’s the surprising thing: higher cholesterol didn’t affect crows’ chances of survival over a three-year period. And in one population, birds with higher cholesterol were arguably in better condition than other crows. Meaning chubbier. 

The results are in the journal the Condor.

Crows can live more than 15 years, and Townsend says maybe a high-cholesterol diet makes its mark later in life, as it does in humans. And if you’re still wondering, “Why study this?”

“But I would say this is an important question, because there are lots of other species that also live in urban areas and eat our food. And some of them are endangered…[full transcript]

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